- **Biochar alone:** Improves the physical structure of the soil, but may have a limited effect on productivity if the soil is poor in nutrients.

- **Compost alone:** Provides essential nutrients, but may not be enough to improve water retention and soil structure in the long term.

- **Biochar-compost blend:** Combines the benefits of both, improving both water retention, soil structure, and nutrient availability, leading to increased productivity of arid soils.

## Exercise 3: Impact of Mixed Biochar-Compost on Soil Biodiversity

**Objective:** Evaluate the effect of the biochar-compost mixture on the biodiversity of sandy soils in the Sahel zone.

**Instructions:**

1. Describe how the application of biochar and compost can influence soil microbial and fungal biodiversity.

2. Propose a methodology to measure changes in biodiversity in soils after application of the biochar-compost mixture.

**Correction:**

1. Influence on soil biodiversity:

- **Biochar:** Provides a habitat for microorganisms by improving soil structure and the availability of ecological niches, which promotes microbial diversity.

- **Compost:** Provides organic nutrients that directly feed microorganisms, increasing their abundance and diversity.

2. Measurement methodology:

- **Soil sampling:** Collect soil samples before and after application of the biochar-compost mixture.

- **Microbial analysis:** Use PCR (Polymerase Chain Reaction) to analyze the DNA of the microorganisms present and evaluate microbial diversity.

- **Counting fungal species:** Use culture techniques on selective media to isolate and identify the fungal species present.

- **Observation of soil fauna:** Measure the diversity of macrofauna (insects, worms) using traps and direct analyzes.

---
## Exercise 4: Case Study - Implementation of Mixed Biochar-Compost

**Objective:** Analyze a case study on the use of the biochar-compost mixture in a Sahelian region.

**Instructions:**

1. Choose a specific region in the Sahel zone where the application of the biochar-compost mixture has been tested.

2. Identify the results obtained in terms of improving agricultural productivity and soil biodiversity.

3. Propose recommendations to improve the effectiveness of this approach in other similar regions.

**Correction:**

1. **Chosen region:** Example, northern Senegal.

2. **Results obtained:**

- **Productivity:** Increase in yields of millet and sorghum crops by 30 to 50% thanks to better water retention and enrichment of the soil with nutrients.

- **Biodiversity:** Increase in microbial and fungal diversity, with a notable increase in earthworm populations, indicators of soil health.

3. **Recommendations:**

- **Local adaptation:** Adjust the proportions of biochar and compost according to specific soil conditions and local crops.

- **Awareness raising:** Train farmers on biochar and compost production techniques, and on the advantages of their combined use.

- **Monitoring and evaluation:** Establish a monitoring system to assess long-term impacts and adjust practices accordingly.

---

These exercises and their corrections offer an in-depth understanding of the effect of the biochar-compost mixture on the productivity and biodiversity of arid sandy soils in the Sahelian zone, highlighting the importance of sustainable resource management for agriculture in arid.
PART 2:
ENVIRONMENT_MANAGEMENT
OF PLANT RESOURCES AND
COOKING ENERGY

<figure><img src="image_28.png" /></figure>
# SOME NOTIONS AND CONCEPTS RELATED TO THE ENVIRONMENT, THE MANAGEMENT OF PLANT RESOURCES AND COOKING ENERGY

Plant resource management and cooking energy are closely linked in many contexts, particularly in Sahelian regions where natural resources are limited and cooking practices have significant environmental impacts. Here's how these two areas interact and strategies to improve their management in a sustainable way:

## 1. Interconnection between Plant Resources and Cooking Energy

### 1.1. Use of Biomass for Cooking

In many regions, biomass, such as wood, charcoal and agricultural residues, is used as an energy source for cooking. This dependence can lead to increased deforestation and land degradation.

The use of biomass for cooking is a common practice in many regions of the world, particularly in rural areas of developing countries such as the Sahelian areas. Biomass includes various organic materials such as wood, charcoal, agricultural residues (such as rice hulls, corn stalks, etc.), and animal waste. Although this practice is an important source of energy for many populations, it also poses environmental, public health, and sustainability challenges.

#### 1.1.1. Types of Biomass Used for Cooking

- **Firewood:** Wood is the most commonly used form of biomass for cooking. It is usually cut from surrounding forests, which can lead to deforestation.

- **Charcoal:** Charcoal is produced by the carbonization of wood under low oxygen conditions. Although more efficient than raw wood, its production and use also contributes to deforestation and air pollution.

<figure><img src="image_29.png" /><figcaption>**Figure 1:** Women's health and indoor air pollution (Ramakrishna, 1995)</figcaption></figure>

- **Agricultural Residues:** Materials such as coconut husks, corn stalks, and other plant residues are often used as fuel. Their use may be more sustainable, but depends on local availability.

- **Animal Waste:** Dried animal droppings are sometimes used as fuel, especially in areas where other types of biomass are rare.

#### 1.1.2. Benefits of Using Biomass
**-Accessibility:** Biomass is often easily accessible and available for free or at low cost, especially in rural areas.

**-Renewable Energy:** Biomass is a renewable energy source if it is managed sustainably, that is to say if the regeneration of resources is ensured.

**-Energy Independence:** The use of biomass can reduce dependence on fossil fuels, particularly in isolated areas.

### 1.1.3. Disadvantages and Challenges

#### a. Deforestation and Land Degradation

- **Unsustainable Cutting:** Excessive cutting of wood for cooking can lead to deforestation, loss of biodiversity, and land degradation, thereby affecting local ecosystems and hydrological cycles.

- **Soil Erosion:** The removal of vegetation cover contributes to soil erosion, reducing its fertility and its capacity to retain water.

#### b. Health Impacts

**-Indoor Air Pollution:** Burning biomass in open fireplaces or inefficient cookers produces a large amount of smoke, which contains fine particles and toxic gases (such as carbon monoxide), which can cause respiratory and heart diseases.

**-Exposure of Women and Children:** Women and children, who spend more time near stoves, are particularly vulnerable to the effects of indoor air pollution.

#### c. Energy Efficiency

**-Low Efficiency:** Traditional combustion methods are often very inefficient, requiring more biomass to produce the same amount of energy, putting increased pressure on natural resources.

### 1.1.4. Solutions for Sustainable Use of Biomass

#### a. Improved Cookers

**-Increased Efficiency:** Improved cookstoves are designed to burn biomass more efficiently, reducing the amount of fuel needed and smoke emissions.

**-Reduction of Emissions:** These cookers reduce emissions of fine particles and harmful gases, thereby improving indoor air quality and reducing health risks.

#### b. Substitution with Modern Fuels

**-Biomass Briquettes:** Agricultural residues and other organic materials can be compressed into briquettes, which burn more cleanly and efficiently than wood or charcoal.
**-Biogas:** Biogas, produced by the anaerobic decomposition of organic waste, is a clean alternative to traditional biomass for cooking.

### c. Sustainable Resource Management

**- Reforestation and Agroforestry:** Plant trees and practice agroforestry to replace used wood resources and improve long-term sustainability.

**-Land Use Planning:** Encourage sustainable land management to avoid deforestation and ensure continued availability of biomass.

### d. Education and Awareness

**- Community Training:** Educate communities on the impacts of deforestation and the benefits of improved cookstoves and sustainable practices.

**- Awareness Programs:** Launch programs to raise awareness about the health risks of indoor air pollution and ways to mitigate them.

#### 1.1.5. Examples of Good Practices

**- Improved Cookstove Programs:** Initiatives like those of the Global Alliance for Clean Cookstoves have helped millions of households switch to more efficient, less polluting cookstoves.

**- Biogas Projects:** In some regions, community biogas projects have been established, offering a sustainable and clean alternative to using biomass for cooking.

## 1.2. Environmental Impacts

Excessive cutting of vegetation for fuel can lead to environmental problems such as loss of biodiversity, land degradation, and diminished water supplies.

The use of biomass for cooking has significant environmental impacts, particularly in regions where it is practiced intensively and unsustainably. These impacts not only affect the local ecosystem, but also contribute to overall environmental challenges. Here are the main environmental impacts associated with this practice:

### 1.2.1. Deforestation

#### a. Loss of Forest Cover

**- Excessive Felling of Trees:** The use of wood as the main source of fuel for cooking often leads to extensive deforestation, particularly in regions where forest management is weak. This leads to a reduction in forest cover, affecting biodiversity and local ecosystems.
**- Ecological Imbalance:** The uncontrolled cutting of trees can cause an ecological imbalance, disrupting natural habitats and endangering many animal and plant species.

## b. Soil Erosion and Desertification

**- Loss of Plant Cover:** Deforestation reduces plant cover, exposing the soil to erosion by water and wind. This can lead to a loss of soil fertility, making land less productive for agriculture and contributing to desertification.

**- Decrease in Water Retention Capacity:** Forests play a crucial role in regulating the water cycle. Their destruction can lead to a reduction in the capacity of soils to retain water, increasing the risk of droughts and floods.

### 1.2.2. Deterioration of Air Quality

#### a. Indoor Air Pollution

**- Pollutant Emissions:** Burning biomass in open fireplaces or inefficient cookers produces significant amounts of smoke, fine particulate matter (PM<sub>2.5</sub>), carbon monoxide (CO), and other toxic gases. These pollutants contribute to poor indoor air quality, which can cause adverse health effects, including respiratory and cardiovascular diseases.

#### b. Outdoor Air Pollution

**- Contribution to Smog:** Emissions of fine particulate matter and gas pollutants can also contribute to smog and outdoor air pollution, affecting the quality of life in communities and exacerbating public health problems on a larger scale.

**- Greenhouse Effect:** Although biomass is a renewable energy source, its inefficient combustion can release carbon dioxide (CO<sub>2</sub>), methane (CH<sub>4</sub>), and black carbon, which are all greenhouse gases contributing to global warming.

### 1.2.3. Disruption of Natural Cycles

#### a. Disruption of the Carbon Cycle

**- Release of Sequestered Carbon:** Forests and other vegetation sequester carbon. Their destruction for firewood releases this carbon into the atmosphere, increasing the concentration of CO<sub>2</sub>, a major greenhouse gas, in the atmosphere.

#### b. Disruption of the Water Cycle

**- Impact on Rainfall Patterns:** Deforestation affects the water cycle, disrupting local rainfall patterns. This can lead to changes in precipitation patterns, exacerbating drought or flood conditions in some areas.

### 1.2.4. Loss of Biodiversity
### a. Habitat Destruction

**Reduction of Natural Habitats:** Cutting trees for fuel leads to the destruction of natural habitats, endangering species that depend on forests for their survival. This can lead to a reduction in biodiversity and, in some cases, the extinction of species.

**Fragmentation of Ecosystems:** Deforestation often leads to the fragmentation of ecosystems, which reduces connectivity between habitats and limits the ability of species to move and reproduce.

### b. Introduction of Invasive Species

**Disturbance of Ecosystems:** The degradation of ecosystems due to biomass extraction can create favorable conditions for invasive species, which can outcompete native species and modify the structure and function of ecosystems.

#### 1.2.5. Contribution to Climate Change

##### a. Greenhouse Gas Emissions

**Direct Emissions:** The combustion of biomass releases CO₂, which directly contributes to global warming. Additionally, inefficient stoves can also emit methane and black carbon, short-lived climate pollutants that have an even more powerful warming effect than CO₂ in the short term.

**Deforestation and Carbon Storage:** Deforestation for the use of biomass reduces the capacity of forests to absorb CO₂, thus amplifying the greenhouse effect and climate change.

#### 1.2.6. Depletion of Natural Resources

##### a. Decrease in Forest Resources

**Pressure on Resources:** The continued extraction of wood for cooking, without adequate reforestation, leads to the depletion of forest resources, compromising the ability of communities to maintain this practice sustainably.

**Impact on Ecosystem Services:** The reduction of forest resources also affects ecosystem services such as air and water purification, climate regulation, and nutrient production.

#### 1.2.7. Solutions to Mitigate Environmental Impacts

##### a. Promotion of Improved Cookers

**Reduction of Emissions:** Improved cookstoves enable more complete combustion of biomass, thereby reducing pollutant emissions and fuel use.

##### b. Development of Alternative Fuels
**- Biomass Briquettes:** Using briquettes made from agricultural residues or organic waste can reduce pressure on forest resources while providing a cleaner fuel source.

**- Biogas:** Encourage the production and use of biogas, which is a cleaner and more sustainable alternative to traditional biomass.

**c. Reforestation and Sustainable Forest Management**

**- Reforestation:** Planting trees to replace those that have been cut down helps restore forests and maintain biodiversity.

**- Agroforestry Practices:** Integrating biomass production into agroforestry systems can provide a sustainable source of firewood while preserving the ecological integrity of the land.

**d. Conservation Policies**

**- Regulation of Deforestation:** Establish policies and regulations to limit deforestation and promote sustainable forest management practices.

**1.3. Energy Efficiency**

**1.3.1. Current State of Energy Efficiency of Traditional Methods**

**a. Traditional Cookers**

**-Open Hearths:** Open hearths, widely used in many rural areas, are extremely inefficient. About 85-90% of the energy produced by combustion is lost as heat which does not contribute to cooking. This means that a large amount of biomass is required to achieve the necessary cooking temperatures.

**-Incomplete Combustion:** The combustion of biomass in open fires is often incomplete due to lack of oxygen and poor temperature control. This not only leads to low energy efficiency, but also to significant emissions of polluting gases such as carbon monoxide and fine particles.

**1.3.2. Technological Improvements to Increase Energy Efficiency**

**a. Improved Cookers**

**- Optimized Design:** Improved cookers are designed to improve biomass combustion. They include devices to better control air and temperature, thereby reducing heat loss and ensuring more complete combustion of fuel.

**-Reduction in Fuel Consumption:** These cookers can reduce firewood consumption by 30% to 60% compared to open fireplaces. This means less biomass is needed for cooking, reducing pressure on forest resources and household energy costs.

**-Decreased Emissions:** By improving combustion efficiency, upgraded cookers also reduce emissions of harmful pollutants, which improves indoor air quality and reduces health risks.

**b. Biomass Gasification**
**-Gasification Cookers:** These cookers convert solid biomass into combustible gas (primarily carbon monoxide, hydrogen and methane) which is then burned for cooking. This process is more efficient than direct combustion because it maximizes the energy extracted from the biomass.

**-Improved Energy Efficiency:** Gasification cookers are much more energy efficient than traditional stoves, and they produce less soot and other air pollutants.

### c. Biomass Briquettes and Pellets

**- Dense Fuels:** Biomass briquettes and pellets are made by compressing agricultural residues or other organic materials. These fuels are denser and have a higher energy content than untreated wood, improving energy efficiency.

**- Even Burning:** Due to their uniform size and composition, briquettes and pellets burn more consistently and efficiently than traditional wood, providing a more consistent heat source and requiring less fuel for the same amount of heat.

### 1.3.3. Benefits of Improving Energy Efficiency

#### a. Reduction of Deforestation

**- Less Biomass Consumption:** By using less biomass to produce the same amount of energy, more efficient technologies reduce pressure on forests, thus contributing to the preservation of natural resources and the fight against deforestation.

#### b. Improved Air Quality

**- Reduction of Pollutant Emissions:** Increased energy efficiency reduces emissions of greenhouse gases (such as CO2) and pollutants dangerous to health (such as fine particles and carbon monoxide), thus improving the quality of indoor and outdoor air.

#### c. Saving Money for Households

**- Less Spending on Fuel:** Households that use more efficient cookstoves spend less on biomass, which can represent significant savings, especially for rural families who rely on purchased or collected firewood.

#### d. Reduction in Wood Collection Times

**- Less Collection Required:** With improved energy efficiency, less time and effort is required to collect biomass, freeing up time for other economic or educational activities, especially for women and children.
### 1.3.4. Challenges and Solutions for the Adoption of More Efficient Technologies

#### a. Access to Technologies

**- Initial Cost:** The initial cost of improved cookstoves or gasification systems can be prohibitive for poorer households. Grant or microfinancing programs can help overcome this barrier.

**- Awareness:** Many communities are unaware of the benefits of more efficient technologies. Education and demonstration campaigns are essential to promote the adoption of these technologies.

#### b. Cultural Adaptability

**- Culinary Preferences:** Cookers must be adapted to local culinary practices to be accepted. This means that they must allow food to be cooked in a traditional way while being more efficient.

#### c. Durability of Materials

**- Maintenance and Repairs:** Technologies must be durable and easy to maintain to ensure their long-term use. It is also crucial to train users in the maintenance of this equipment.

### 1.3.5. Examples of Successful Programs

**- The Clean Cookstove Alliance:** This global program aims to distribute improved cookstoves to the most vulnerable communities, thereby reducing biomass consumption and improving public health.

**- Microfinance Initiatives:** Microfinance projects allow households to acquire improved cookstoves on credit, making these technologies accessible to more people.

### 1.3.6. Strategies for Sustainable Management of Plant Resources and Cooking Energy

#### a. Promoting Efficient Cooking Technologies

**-Improved Ovens and Cookers:** Develop and disseminate more efficient cooking technologies, such as energy-efficient stoves and fuel-saving cookers, which reduce biomass consumption and emissions.

**-Renewable Energy Cookers:** Encourage the use of cookers powered by renewable energy sources, such as solar energy, to reduce dependence on fossil fuels and biomass.

#### b. Encouraging Sustainable Management Practices for Plant Resources
**- Reforestation and Sustainable Forest Management:** Implement reforestation programs to compensate for logging and promote sustainable forest management to maintain forest ecosystems.

**- Use of Agricultural Residues:** Encourage the use of agricultural residues and organic waste as an alternative to wood for cooking, thus reducing pressure on forests.

**c. Education and Awareness**

**-Awareness Programs:** Launch awareness campaigns on the environmental impacts of traditional cooking practices and promote more sustainable alternatives.

**-Community Training:** Train local communities on efficient cooking techniques and plant resource management practices, with an emphasis on economic and environmental benefits.

**d. Innovation and Research**

**-Research on Cooking Technologies:** Invest in the research and development of new, cleaner and more efficient cooking technologies that use less biomass and emit fewer pollutants.

**-Development of Alternative Fuels:** Explore and promote sustainable alternative fuels, such as biomass briquettes or biogas, to replace wood and charcoal.

**e. Policies and Regulations**

**-Forest Conservation Policies:** Implement policies to protect forests and regulate logging to avoid deforestation and soil degradation.

**-Incentives for Sustainable Technologies:** Provide financial incentives, such as grants or tax credits, for the adoption of cleaner cooking technologies and sustainable plant resource management practices.

**f. Partnerships and Collaboration**

**-Public-Private Partnerships:** Collaborate with businesses, NGOs and government agencies to promote sustainable solutions and facilitate access to improved technologies.

**-Community Initiatives:** Support community initiatives that seek to improve cooking practices and the management of plant resources through local projects and cooperatives.

**1.3.7. Examples of Good Practices**

**- Pellet Cookers:** The use of pellet cookers, which are more efficient than traditional fireplaces, helps reduce wood consumption and harmful gas emissions.

**- Biomass Boilers:** Modern biomass boilers, used for heating and cooking, allow more efficient management of plant fuels and reduced emissions.
**- Reforestation Projects:** Community reforestation projects that plant trees to restore degraded forests and provide long-term sustainable firewood.

In short, although biomass is an essential energy source for many communities, its environmental impacts are considerable. The promotion of more efficient technologies, the development of alternative fuels, and the implementation of sustainable resource management strategies are crucial to mitigate these impacts and ensure the long-term sustainability of this practice.

Improving energy efficiency in the use of biomass for cooking is essential to reduce environmental impacts, improve public health and maximize available resources. Modern technologies such as improved cookstoves, gasification cookers, and biomass briquettes represent viable solutions to achieve these goals. However, to ensure large-scale adoption, it is necessary to overcome challenges related to access, awareness, and durability of equipment.

By integrating these strategies, it is possible to manage plant resources more sustainably while improving energy efficiency in cooking, thereby contributing to environmental protection and reducing negative impacts on ecosystems and communities.

# EXERCISES AND ANSWERS ON ENVIRONMENTAL EDUCATION, MANAGEMENT OF PLANT RESOURCES FOR COOKING AND CLIMATE CHANGE

Here is a series of exercises accompanied by their answers, covering the three themes: environmental education, management of plant resources for cooking, and climate change.

---

## Theme 1: Environmental Education

### Exercise 1: Analyze a Local Ecosystem

**Objective:** Study a local ecosystem and understand the interactions between its components.

**Instructions:**

1. Choose a local ecosystem (park, river, forest, etc.).

2. Identify the different elements that make up this ecosystem (plants, animals, soil, water, etc.).
3. Describe how these elements interact with each other and what the impact of human activities on this ecosystem is.

**Correction:**

- **Identified elements:** In a forest, for example, we find trees, shrubs, insects, birds, mammals, mushrooms, etc.

- **Interactions:** Trees provide habitat and food for animals, insects pollinate plants, and fungi decompose organic matter, enriching the soil.

- **Impact of human activities:** Deforestation, river pollution and urbanization can destroy habitats, reduce biodiversity and disrupt natural interactions.

## Exercise 2: Awareness Campaign

**Objective:** Design a campaign to raise community awareness of an environmental issue.

**Instructions:**

1. Choose a local environmental problem (pollution, deforestation, waste management).

2. Develop a plan for an awareness campaign (posters, social media and workshops).

3. Indicate the key messages you want to communicate and the actions you propose.

**Correction:**

- **Selected problem:** Plastic pollution.

- **Campaign plan:** Distribution of informative leaflets, recycling workshops, use of social media to promote alternatives to plastic.

- **Key messages:** "Reduce, reuse, recycle", "Every action counts", "Let's replace single-use plastic with sustainable solutions".

- **Proposed actions:** Encourage the use of reusable bags, organize waste collections and promote selective sorting.

---

## Theme 2: Management of Plant Resources for Cooking

### Exercise 1: Evaluating the Effectiveness of Improved Stoves
**Objective:** Compare wood consumption between a traditional fireplace and an improved fireplace.

**Instructions:**

1. Calculate the amount of wood consumed by a traditional household to prepare an average meal.

2. Compare this quantity to that used by an improved stove.

3. Discuss the economic and environmental benefits of improved cookstoves.

**Correction:**

- **Traditional fireplace:** Consumes 5 kg of wood for a meal.

- **Improved Hearth:** Consumes 2.5 kg of wood for the same meal.

- **Benefits:**

- **Economical:** Halving the costs associated with the purchase of wood.

- **Environmental:** Less pressure on forest resources, reduction of CO₂ emissions.

**Exercise 2: Sustainable Resource Management Plan**

**Objective:** Develop a plan for the sustainable management of plant resources in a community.

**Instructions:**

1. Identify the main plant resources used for cooking in the community.

2. Propose measures to ensure sustainable use of these resources (reforestation, improved stoves).

3. Describe how these measures can be implemented and the expected benefits.

**Correction:**

- **Identified resources:** Wood, agricultural residues.

- **Proposed measures:**

- **Reforestation:** Planting trees to replace those cut down.

- **Improved stoves:** Promote the adoption of more efficient stoves.

- **Awareness:** Educate the community on the importance of sustainable management.
- Expected benefits: Reduction in deforestation, improvement in health thanks to less smoke, reduction in energy costs for homes.

---

## Theme 3: Climate Change

### Exercise 1: Calculation of the Carbon Footprint

**Objective:** Estimate CO₂ emissions from a daily activity.

**Instructions:**

1. Estimate the CO₂ emissions generated by using a car for a 50 km journey (average emissions of 120 g of CO₂ per km).

2. Calculate the annual carbon footprint for this trip if it is taken daily.

3. Propose alternatives to reduce these emissions.

**Correction:**

- **Emissions for 50 km:** 50 km × 120 g/km = 6,000 g = 6 kg of CO₂.

- **Annual emissions:** 6 kg × 365 days = 2,190 kg = 2.19 tons of CO₂.

- **Alternatives:** Carpooling, using public transport, cycling, switching to an electric car.

### Exercise 2: Case Study: Effects of Climate Change

**Objective:** Analyze the impacts of climate change on a specific sector.

**Instructions:**

1. Choose a sector (agriculture, health and infrastructure).

2. Identify the effects of climate change on this sector.

3. Propose adaptation strategies to minimize impacts.

**Correction:**

- **Chosen sector:** Agriculture.

- **Identified effects:**

- Changes in planting seasons.

- Increased episodes of drought.

- Reduction in agricultural yields.
- Coping strategies:

- Adoption of drought-resistant crop varieties.

- Improved irrigation and water management.

- Crop diversification to reduce risks.

---

These exercises cover various aspects of environmental education, management of plant resources for cooking, and climate change, allowing a comprehensive approach to these essential subjects.
# CHAPITRE 1. EFFECTS OF ECOLOGICAL CHARCOAL PRODUCTION PROCESSES BASED ON *EICHHORNIA CRASSIPES* ON ITS CHARACTERISTICS AS COOKING ENERGY

Alexis Dzokom<fnref n="1" />, Ezekiel KODJI<fnref n="1" />, Joël Tizé Koda<fnref n="2" />, Roger Djouldé Darman<fnref n="3" />

## ABSTRACT

*Eichhornia crassipes* is an invasive plant in the waters of Lake Chad. The ecological problems caused by its permanent and invasive presence lead to search solutions. Thus its valuation as cooking energy is an option whose objective is to assert the effect of production processes of ecological coal based on *Eichhornia crassipes* on their performance as cooking energy. The collection and sorting of these plants made it possible to prepare the raw material while their pre-treatment made it possible to carry out the anaerobic carbonization between 400-600°C on the one hand, and on the other hand, the semi-decomposition of *Eichhornia crassipes* biomass allowed us to have a raw material ready after 14 ± 03 days. Hydrocalorific characterization show that the ecological charcoal based on decomposed *Eichhornia crassipes* has 4.401±0.972% as moisture content average with a calorific value average of 17.825±8.308 MJ/Kg. The ecological charcoal based on carbonized *Eichhornia crassipes* has 3.79±1.05% as moisture content with average calorific value 21.05±7.76 MJ/Kg. The chemical characterization show that the ecological charcoal based on charred *Eichhornia crassipes* has an average volatile matter rate of 26.87 ± 1.55%, a low average fixed carbon rate of 86.73 ± 2.67% and an average ash content 2.69 ± 0.33% while ecological coal based on decomposed *Eichhornia crassipes* has an average volatile matter rate of 22.059 ± 1.298%, an average fixed carbon rate of 74.496 ± 1.716% and an average ash content of 1.97 ±0.72%. The Improved Culinary Furnace test, charred *Eichhornia crassipes* charcoal bonded to clay lasts in the fire longer time average, 46 minutes 10 seconds, when burning emitting 6.72±1.49 grams of ash average with 93.02±0.91% as mass loss average while the decomposed *Eichhornia crassipes* charcoal has a low burning time, 43 minutes 33 seconds, emitting 12.01±0.09 grams as ash average with 90.05±0.95% as mass loss average.

**Keywords:** *Eichhornia crassipes*, ecological charcoal, charcoal briquette

## INTRODUCTION

<footnote n="1">¹Department of Environmental Sciences, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>

<footnote n="2">²Department of Renewable Energy, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>

<footnote n="3">³Department of Agriculture Animal Husbandry and By-Products, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>
*Eichhornia crassipes* is a free-floating aquatic plant on water's surface. Native to the Amazon basin in South America, this macrophyte aquatic plant, of the Pontederiaceae family and whose name Eichhornia is derived from the well-known 19th century Prussian politician, J.A.F. Eichhorn, is the most difficult to control in the world [1,2,3,4]. Widespread throughout the world in the late 19th and early 20th century, today this tropical plant is well known for its rapid reproductive capacity whose population can double in just twelve days [5, 6 and 7]. *Eichhornia crassipes* proliferation's makes it an invasive plant, raising it to the same level as weeds. Its germination and spread are rapid when environmental and ecological conditions are met. Ecological damage then ensues, such as: the obstruction of navigation routes; the disappearance of certain aquatic species; the disappearance of fishing areas and the appearance of certain waterborne diseases such as malaria. During their period of proliferation, whatever the mitigation methods applied, *Eichhornia crassipes* disappears in one place to resurface just as quickly in another place [8]. However, although it is possible to control it biologically and naturally, the persistence of favorable environment to their reproduction, such as that the abundance of space and nutrients doubled at a good medium temperature cause this plant to spread so prolifically that it covers water's surfaces in record time with a floating mat-like cover [9,10]. Considered as an ornamental plant by gardeners and botanists, because of its pretty purplish blue flowers and its round and oval leaves, *Eichhornia crassipes* was propagated in many countries such as Latin America, the Caribbean, Africa, Southeast Asia and the Pacific more than a century ago because it was highly prized [9, 10, 11 and 12]. *Eichhornia crassipes* seeds hibernate over a dormant period of 15 to 20 years. *Eichhornia crassipes* contains lignocellulose (60% cellulose, 8% hemicellulose and 17% lignin) and a good part of carbon nitrate, which gives it characteristics of an alternative directly usable as renewable energy source [14, 15].

Rising prices of fossil energy and the problem of global warming have led to a major effort to promote renewable energies. This has intensified the search for alternatives to fossil fuels to facing modernization and industrialization [9]. Exacerbated by soaring energy costs, water hyacinth holds great promise in this regard for the biofuels industry of the 21st century [16]. The production methods developed by [9] made it possible to produce ecological coal of high value. The pyrolysis (or carbonization) method between [400-800] °C converts raw materials into carbon by minimizing the volatile matter content and increasing the carbon content of the material. In this study, the objective is to produce ecological charcoal based on *Eichhornia crassipes* to contribute to the fight against the invasion of Lake Chad water's surfaces.

# 1. MATERIALS AND METHODS

## 1.1. Study zone

This study was carried out in five districts around Lake Chad on the Cameroon side. Villages crossed by this lake experience the invasion of Lake Chad water's surfaces by *Eichhornia crassipes*. These areas have been represented in the following table:
<figure><img src="image_30.png" /><figcaption>Figure 1: Map of the study area</figcaption></figure>

## 1.2. Eichhornia crassipes briquette manufacturing process

### a) Preparation of the raw material

The overall preparation process was carried out according to the following scheme:

<figure><img src="image_31.png" /><figcaption>Figure 2: Raw material preparation scheme</figcaption></figure>

### b) Carbonization process
The carbonization was carried out following the methodology developed by [28]. It consisted in carbonizing the dry biomass in a carbonizer at a temperature between 400-600°C.

<figure><img src="image_32.png" /><figcaption>Figure 3: Scheme of production of ecological charcoal based on Eichhornia crassipes</figcaption></figure>

During the carbonization, biochar is produced, of blackish color which, crushed, sieved and mixed with the binder, can be molded through a manually operated compaction and extrusion system to obtain ecological charcoal/ecological briquettes.

### c) Semi-decomposition process

During semi-decomposition, the methodology developed by [9] consisted of decomposing the biomass in a hermetically sealed plastic bag. The materials used are: Biomass: chopped and dried stem of *Eichhornia crassipes*, Polyethylene decomposition bags (plastic bag with a thickness of more than 60µm, microorganism decomposition solution (EM1 solution) to accelerate the decomposition activity of microorganisms on the stem of chopped and dried Eichhornia crassipes. The process of semi-decomposition lasts about 14 ± 03 days with reversals after every 07 ± 02 days.

## 1.3. Hygro-calorific characterization of Eichhornia crassipes's charcoal

### 1.3.1. Moisture content

Determination of the moisture content was inspired by the methodological measurement procedures developed by [17]. Moisture content expresses the water content and has a strong influence on the calorific value and the ignition
capacity of charcoal briquettes. Moisture content is obtained by the following formula:

$$W(\%) = \frac{(M\text{Wet} - M\text{Dry})}{(M\text{Dry})} \times 100 \quad (1)$$

With: W: moisture content; M wet: mass of the sample; M dry: mass obtained after heating at 105°C in an oven.

### 1.3.2. Calorific value

[20] method and the MA protocol, 108-P.Cal. 1.0 helped measure and calculate calorific value. The heat capacity of the bomb and the tank was calculated from a test made with benzoic acid. The calorific value of samples is measured by the following equation:

$$P. C. = \frac{([1000 \times (T^{\circ}\text{f} - T^{\circ}\text{i}) \times W - (Hh \times a)]}{b}}{(2) \quad (1)}$$

Where P.C.: calorific value of the sample (kJ/kg); T°f: maximum final temperature of the water in the tank after firing (°C)

## 1.4. Chemical characterization of Eichhornia crassipes's charcoal

### 1.4.1. Volatile matter rate

BS EN 14,774-1 protocol for determination of volatile matter of fuel consists in weighing the dry sample heating under nitrogen, between 890° and 910°C temperature for 7 minutes in a crucible with lid and weigh again. The formula developed by the standard method [18] is used to calculate the volatile matter content:

$$M. O. V. = \frac{((M850^{\circ}\text{C} - M899^{\circ}\text{C}) \times 100)}{M\text{dry}} \quad (3)$$

With: MOV: Volatile matter content, M895°C: Mass obtained after heating to 895°C, M899°C: mass obtained after heating to 899°C

### 1.4.2. Ash content

Ash content is the quantity of very small mineral matter contained in a fuel and released after complete combustion, under the effect of heat at high temperatures. The result is obtained by applying the formula developed by the standard methods [19] and [20]:

$$A(\%) = \frac{(M850^{\circ}\text{C} \times 100)}{M\text{dry}} \quad (4)$$

With: A, M850°C: mass of the powder obtained after incineration at 850°C, M dry: dry mass of the sample.

### 1.4.3. Fixed carbon content

To determine fixed carbon, BS EN 14.774-1 protocol was used. Two parts of combustible briquettes, each weighing 1 gram, were made, then they were introduced into an oven for calcination. One part was calcined for 10 minutes at 550°C, while other part was calcined for 10 minutes at 850°C. The fixed carbon content developed by the standard method [20] allows to calculate using the following formula:

$$Cf(\%) = 100 - (H\text{sec} + M\text{ce850}^{\circ}\text{C} + M\text{v550}^{\circ}\text{C}) \quad (5)$$
## 1.5. Combustion tests

Combustion test allowed us to determine: Burning time of each combustible briquette; post-combustion mass (ash) and the loss mass.

# 2. RESULTS AND DISCUSSIONS

## 2.1. *Eichhornia crassipes* briquette manufacturing process

### 2.1.1. Preparation of raw material by carbonization

Preparation of *Eichhornia crassipes* raw's material by carbonization gave the following results:

<table><caption>Table 1: *Eichhornia crassipes* raw material prepared by carbonization</caption><thead><tr><th>Raw material</th><th>Quantities (gram)</th><th>Binder (0.5mm)</th><th>Particle size (mm)</th></tr></thead><tbody><tr><td>Leaf and branch</td><td>300</td><td rowspan="4">Kaolin clay</td><td>0.5 to 1</td></tr><tr><td>Stem, branch and root</td><td>300</td><td>0.5 to 1</td></tr><tr><td>Stem and branch</td><td>300</td><td>0.5 to 1</td></tr><tr><td>Whole plant</td><td>300</td><td>0.5 to 1</td></tr></tbody></table>

### 2.1.2. Preparation of raw material semi-decomposition

Preparation of *Eichhornia crassipes* raw's material by semi-decomposition gave, after 14 days, the following results:

<table><caption>Table 2: *Eichhornia crassipes* raw material prepared by semi-decomposition</caption><thead><tr><th>Raw material</th><th>Quantities (gram)</th><th>Binder (0.5mm)</th><th>Particle size (mm)</th></tr></thead><tbody><tr><td>Leaf and branch</td><td>500</td><td rowspan="4">Kaolin clay</td><td>0.5 to 1</td></tr><tr><td>Stem, branch and root</td><td>500</td><td>0.5 to 1</td></tr><tr><td>Stem and branch</td><td>500</td><td>0.5 to 1</td></tr><tr><td>Whole plant</td><td>500</td><td>0.5 to 1</td></tr></tbody></table>

### 2.1.3 Hygro-calorific characterization of *Eichhornia crassipes*'s charcoal

Clay-bound charred *Eichhornia crassipes* charcoal (98-02%) has a lower calorific value average of 14.67±2.01 MJ/Kg while clay-bound charred *Eichhornia crassipes* charcoal_Wood chips (70-28-02%) has 27.442±5.26 MJ/Kg calorific value average. Among these samples, clay-bound carbonized *Eichhornia crassipes* leaf charcoal (98-02%) has the highest calorific value, 17.656±0.097 MJ/Kg, while charcoal from carbonized *Eichhornia crassipes* stem bound clay (98-02%) and/or the whole plant of carbonized *Eichhornia crassipes* bound to clay (98-02%) have the same calorific value 13.472±0.012 MJ/Kg. It is found that among *Eichhornia crassipes* carbonized charcoal_Wood chips, charcoal from the leaves of *Eichhornia crassipes* carbonized_woodchips bound with clay (70-28-02%) has the bigger calorific value
33.137± 0.054 MJ/Kg while whole plant charcoal_woodchip _Clay-bound (70-28-02%) has the smallest calorific value 22.015± 0.017 MJ/Kg.

Charcoal from decomposed *Eichhornia crassipes* bound to clay (98-02%) has an average calorific value 12.755±1.703 MJ/Kg while charcoal from decomposed *Eichhornia crassipes* _Chips wood bound to clay (70-28-02%) has a calorific value of 22.895±9.466 MJ/Kg. Among these samples, charcoal from leaves and branches of *Eichhornia crassipes* decomposed _ wood chips bound to clay (70-28-02%) has the highest calorific value of 31.336± 0.017 MJ/Kg while charcoal from stems and branch of decomposed *Eichhornia crassipes* bound to clay (98-02%) has the smallest calorific value 11.012± 0.042 MJ/Kg.

Overall, it appears that among the charred *Eichhornia crassipes* charcoal briquettes has the highest average calorific value of 21.05±7.76 MJ/Kg while the decomposed *Eichhornia crassipes* charcoal has the lowest average calorific value which is 17.825±8.308 MJ/Kg.
<figure><img src="image_33.png" /><figcaption>Graph 1: Calorific value of samples of ecological charcoal based on *Eichhornia crassipes*</figcaption></figure>

These results corroborate those found by [20, 9] who found that charcoal from *Eichhornia crassipes*-wood chips produced greater heat intensity while being cleaner, more convenient and took up less space when stored.

Ecological charcoal made from decomposed *Eichhornia crassipes* has moisture content (4.401±0.972%) while Ecological charcoal made from charred *Eichhornia crassipes* has moisture content of 3.79±1.05%. Charcoal from whole plant
*Eichhornia crassipes* _wood chips has the highest moisture content 5.85±0.12% while charcoal from charred *Eichhornia crassipes* leaves and branches has the lowest moisture content 2.71 ±0.43%. This state of humidity is higher in the briquettes resulting from the semi-decomposition than those resulting from the carbonization process because carbonized *Eichhornia crassipes* was able to release the excess free water by dry dehydration, during carbonization

<figure><img src="image_34.png" /><figcaption>Graph 2: Plot of moisture content trends against calorific value</figcaption></figure>

There is an inverse relationship between calorific value and moisture content (Graph 2). The plot of the trends of the moisture content of ecological charcoal based on *Eichhornia crassipes* shows that the linear calorific value is ascending when that of the moisture content is descending. Ecological charcoal made by using *Eichhornia crassipes* from the semi-decomposition method has a higher dry moisture content than Ecological charcoal by using *Eichhornia crassipes* from the carbonization method. Overall, following the trend lines, when the humidity increases, it causes a decrease in its calorific value and vice versa. This confirms the results of [22] which indicate that the calorific value is influenced by the moisture content. The range of moisture content in the dry state does not lead to remarkable energy loss during the vaporization of the moisture present and their stability during storage is considerable [23]. Ecological charcoal made from *Eichhornia crassipes* have good characteristic because their dry relative moisture content is between 2.71% and 5.85%, lower than that of wood charcoal 6% [24].
### 2.1.4. Chemical characterization of *Eichhornia crassipes*'s charcoal

#### 2.1.4.1. Volatile matter content

Ecological charcoal based on carbonized *Eichhornia crassipes* has an volatile matter content average of 26.87±1.55% while that of ecological charcoal based on decomposed *Eichhornia crassipes* is 22.059±1.298%, in accordance with the conclusions of [24], but contrary to those of [25] who insist that woody biomasses have higher levels of volatile matter than other biomasses. Charcoal from clay-bound carbonized *Eichhornia crassipes* stems (98-02%) has the highest volatile matter content of 28.59±0.87%, possibly due to the process of carbonization of the structure stems of *Eichhornia crassipes* which helps it to retain a high level of volatile matter in the carbonized material, better than by the process of semi-decomposition. Charcoal from the leaves and branches of *Eichhornia crassipes* semi-decomposed_wood chips has the lowest volatile matter content (20.14±0.18%).

#### 2.1.4.2. Ash content

Ash content average of charred *Eichhornia crassipes* charcoal is 2.69±0.33% (with respectively 2.912±0.097% for charred *Eichhornia crassipes* charcoal_woodchips and 2.477±0.343% for charred *Eichhornia crassipes* charcoal), while charcoal from decomposed *Eichhornia crassipes* has 1.972±0.719% ash content (with respectively 2.615±0.2456% for charcoal from *Eichhornia crassipes_wood chips* decomposed and 1.33±0.21% for anthrax from decomposed *Eichhornia crassipes*). Our results, concerning decomposed *Eichhornia crassipes* charcoal, are close to those concluded by [26] which indicate that the ash content of woody biomass is between 0.08% and 2.3%. Decomposed *Eichhornia crassipes* charcoal has a lower average ash content, possibly due to the addition of woodchip (which would be a non-woody vegetable) and clay binder which would act as a filler, thus contributing to a higher ash content and possibly also due to their low carbon binding capacity [27, 9].

#### 2.1.4.3. Fixed carbon content

Carbonized *Eichhornia crassipes* charcoal has a low fixed carbon content (86.73±2.67%) (With 89.035±0.905% for charred *Eichhornia crassipes_woodchips* and 84.43±1.29% for charcoal carbonized *Eichhornia crassipes*) compared to their decomposed counterparts which has 74.496±1.716% (with 73.707±0.444% for decomposed *Eichhornia crassipes* charcoal and 75.285±2.241% for *Eichhornia crassipes* charcoal_woodchips).
<figure><img src="image_35.png" /><figcaption>Graph 3: Chemical characteristics of *Eichhornia crassipes* fuel samples</figcaption></figure>

2.1.4.4. Combustion/cooking test

Charcoal cooking test of charred *Eichhornia crassipes* with a cooking stove improved made it possible to boil 01 liter of water in 15 minutes 20 seconds and 250 grams of rice in 25 minutes 46 seconds. The average burning time of charred *Eichhornia crassipes* charcoal is 44 minutes 52 seconds with post-combustion mass (ash) of 14.36±0.22 milligrams/Kilogram of Ecological charcoal and an average mass loss of 86.75± 0.01%

charred *Eichhornia crassipes* charcoal Clay bound lasts on average longer in the fire (46 minutes 10 seconds) when burning while decomposed *Eichhornia crassipes* charcoal has a low burn time (43 minutes 33 seconds) (Table 3)
<table><caption>Table 3: Cooking test with samples of *Eichhornia crassipes* briquettes</caption><thead><tr><td>Samples</td><td>Burning time (s)</td><td>Mass of post-combustion fuel (gr)</td><td>Mass loss (%)</td></tr></thead><tbody><tr><td>Carbonized <i>Eichhornia crassipes</i> charcoal</td><td>2208±3.81</td><td>08.59±0.91</td><td>75±0.5</td></tr><tr><td>Charcoal from Eichhornia crassipes Charred woodchips</td><td>3276±3.81</td><td>24.85±0.43</td><td>91±0.8</td></tr><tr><td>Decomposed Eichhornia crassipes smut</td><td>2204±1.53</td><td>02.51±0.15</td><td>87±0.3</td></tr><tr><td>Charcoal from Eichhornia crassipes decomposed woodchips</td><td>2996±4.39</td><td>21.49±0.29</td><td>94±0.9</td></tr></tbody></table>

After 60 minutes of combustion, carbonized Eichhornia crassipes charcoal emits an average of 6.72±1.49 grams of ash with an average mass loss of 93±0.9%, while decomposed Eichhornia crassipes charcoal emits an average of 12.01±0.09 grams of ash with an average mass loss of 90.05±0.95%.

CONCLUSION

The objective of this study was to determine the effect of green charcoal production processes on their performance as cooking energy. Overall, it appears that carbonized *Eichhornia crassipes* charcoal briquettes perform better than decomposed *Eichhornia crassipes* charcoal briquettes. Indeed, on the hydro-calorific level, ecological coal based on decomposed *Eichhornia crassipes* has a moisture content of 4.401 ± 0.972% with a low calorific value average (17.825 ± 8.308 MJ / Kg) while ecological coal based on carbonized *Eichhornia crassipes* has a low moisture content of 3.79±1.05% with a high average calorific value of 21.05±7.76MJ/Kg.

Chemical characterization show that the ecological charcoal based on charred *Eichhornia crassipes* has volatile matter average rate (26.87±1.55%) and low fixed carbon average (86.73±2.67%) and ash content average (2.69 ± 0.33%) while ecological charcoal based on decomposed *Eichhornia crassipes* has volatile matter content average (22.059 ± 1.298%), and fixed carbon content average (74.496 ± 1.716%) and ash content average (1.97 ± 0.72%).

In terms of improved cook stove applicability, charred *Eichhornia crassipes* charcoal bounded to clay lasts on average longer in the fire (46 minutes 10 seconds) during combustion emitting an average of 6.72±1, 49 grams of ash with an average mass loss of 93.02±0.91% while decomposed *Eichhornia crassipes* charcoal has a low burn time (43 minutes 33 seconds), emitting an average of 12.01±0, 09 grams of ash with an average mass loss of 90.05 ± 0.95%. From the point of view of cooking energy, charred *Eichhornia crassipes* charcoal woodchip bound with clay has a better efficiency in the
stove. In the case where one would like to proceed by decomposition of the biomass,
the decomposed *Eichhornia crassipes* charcoal_woodchips and bound to the clay would
be just as interesting.

**Bibliographic reference**

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[23] Aina, O., Adetogun, A., & Iyiola, K. (2009). Heat Energy from Value - added Sawdust Briquettes of Albizia Zygia. *Ethiopian Journal of Environmental Studies and management*, Vol 2 No. 1 2009.
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[26] Nurmi. (1993). Heating Values of Whole- Tree Biomass in Young Forests in Finland. *Acta Forestalia Fennica* 236. *Tampere*.

[27] Cook, J. (1990). *Origin Autoecology and spread of some of the World's Most Troublesome Aquatic Weeds*. In Pieterse, A., Murphy, K. (Eds.), *Aquatic Weeds: The Ecology and Management of Nuisance Aquatic Vegetation*. Oxford, UK: Oxford University Press.

# EXERCISES AND CORRECTIONS ON THE EFFECTS OF ECOLOGICAL CHARCOAL PRODUCTION PROCESSES BASED ON EICHHORNIA CRASSIPES ON ITS CHARACTERISTICS AS COOKING ENERGY

Here is a series of exercises accompanied by their answers on the theme of the effects of ecological charcoal production processes based on *Eichhornia crassipes* (water hyacinth) on its characteristics as cooking energy.

---

**Exercise 1: Understanding the Characteristics of *Eichhornia crassipes* for Ecological Coal Production**

**Objective:** To analyze the properties of *Eichhornia crassipes* as a raw material for the production of ecological charcoal.

**Instructions:**

1. Identify the physicochemical properties of *Eichhornia crassipes* that make it a viable raw material for the production of environmentally friendly charcoal.

2. Compare these properties with those of other biomasses commonly used to produce charcoal (such as wood or agricultural residues).

**Correction:**

1. Physico-chemical properties of *Eichhornia crassipes*:

- **Moisture content:** Relatively high, requiring drying before carbonization.

- **Ash content:** Moderate, influences the quality of the coal.
**Energy content:** Sufficient to produce charcoal with an acceptable energy density for cooking.

**Availability and rapid growth:** Makes this biomass abundant, particularly in humid areas.

**2. Comparison with other biomasses:**

**Wood:** Generally, wood has a lower moisture content and higher energy density than Eichhornia crassipes. However, wood may be less sustainable due to deforestation.

**Agricultural residues:** These residues have variable moisture and ash content, sometimes higher than those of *Eichhornia crassipes*, but are also renewable and available in large quantities.

---

**Exercise 2: Analysis of Production Processes**

**Objective:** To study the different stages of the production process of ecological charcoal based on *Eichhornia crassipes* and their effects on the characteristics of the final product.

**Instructions:**

1. Describe the main stages of the process of producing ecological charcoal from *Eichhornia crassipes* (harvesting, drying, carbonization, etc.).

2. For each step, explain how it influences the characteristics of the final coal (density, ash content, calorific value).

**Correction:**

**1. Main steps:**

**Harvest:** Collection of *Eichhornia crassipes* in infested areas.

**Drying:** Reduction of the moisture content of the biomass to facilitate carbonization.

**Carbonization:** Conversion of biomass into coal at high temperature in the absence of oxygen.

**Grinding and compaction:** Transformation of coal into briquettes to facilitate its use as cooking energy.

**2. Influence of the stages on the characteristics of the coal:**

**Drying:** The more efficient the drying, the denser the coal will be and will have a higher calorific value. Poor moisture evaporation can reduce coal quality.
- **Carbonization:** The temperature and duration of carbonization determine the fixed carbon content, energy density, and ash content of the coal. Controlled carbonization produces coal with good energy density and low ash content.

- **Compaction:** Improves the density of the charcoal, making the briquettes more durable and efficient for cooking.

---

## Exercise 3: Evaluation of the Quality of Ecological Coal

**Objective:** Compare the quality of ecological charcoal based on *Eichhornia crassipes* with that of traditional charcoals.

**Instructions:**

1. Measure the following properties of the ecological charcoal made from *Eichhornia crassipes*: calorific value, density, ash content.

2. Compare these results with those of charcoal produced from wood or agricultural residues.

3. Discuss the advantages and limitations of eco-friendly coal as a cooking energy.

**Correction:**

**1. Properties measured:**

- Calorific value: For example, 18 MJ/kg.

- Density: 0.8 g/cm³.

- Ash content: 10%.

**2. Comparison with other coals:**

- **Charcoal:** Higher calorific value (20-25 MJ/kg), variable but often higher density, lower ash content (less than 5%).

- **Coal from agricultural residues:** Calorific value similar to that of *Eichhornia crassipes* coal, but with variability depending on the type of residue, density and ash content also variable.

**3. Advantages and limitations:**

- **Advantages:** Abundant and renewable resource, low production cost, reduction of the environmental impact linked to the elimination of water hyacinth, sustainable alternative to deforestation.
**- Limitations:** Calorific value slightly lower than that of charcoal, possible variation in quality depending on the production process, need for awareness raising for its large-scale adoption.

---

**Exercise 4: Case Study - Socio-Economic Impact of the Use of Ecological Coal**

**Objective:** Analyze the socio-economic impacts of the use of ecological charcoal based on *Eichhornia crassipes* in a community.

**Instructions:**

1. Choose a community where eco-friendly coal has been introduced.

2. Assess the effects of this introduction on local livelihoods, natural resource management, and reduction of deforestation.

3. Propose improvements to maximize the socio-economic benefits of this initiative.

**Correction:**

1. **Selected community:** Example, a rural lakeside community in Kenya.

2. **Effects observed:**

**- Livelihoods:** Creation of local jobs in the collection, production and sale of ecological charcoal. Reduction of energy costs for households.

**- Natural resource management:** Reduction in the proliferation of water hyacinth, which improves navigation and fishing in the lake. Less dependence on firewood, contributing to the preservation of local forests.

**- Reduction in deforestation:** Adoption of ecological charcoal has reduced pressure on forests, contributing to the conservation of forest ecosystems.

3. **Proposed improvements:**

**- Training and awareness:** Intensify training programs to improve the quality of coal produced and raise awareness of its benefits.

**- Technical and financial support:** Provide access to more advanced technologies for coal production, and develop financing mechanisms to support small producers.

**- Market expansion:** Create new outlets for ecological coal, particularly in urban areas where energy demand is higher.

---

These exercises and answers allow us to explore in depth the effects of ecological charcoal production processes based on *Eichhornia crassipes* on its characteristics as a cooking energy, highlighting the advantages and challenges associated with this sustainable alternative.
# CHAPITRE 2. STUDY OF THE PERFORMANCE OF ORGANIC AND INORGANIC BINDERS FOR THE PRODUCTION OF ECOLOGICAL CHARCOAL FUELS BASED ON DEAD BIOMASS OF AZADIRACHTA INDICA

Alexis Dzokom¹, Ezekiel KODJI¹, Joël Tizé Koda², Roger Djouldé Darman³

¹Department of Environmental Sciences, National Advanced School of Engineering, University of Maroua, Cameroon

²Department of Renewable Energy, National Advanced School of Engineering, University of Maroua, Cameroon

³Department of Agriculture Animal Husbandry and By-Products, National Advanced School of Engineering, University of Maroua, Cameroon

## ABSTRACT

In Sahelian cities, desertification with its climatic corollary is due to the excessive use of firewood by increasingly growing populations. However, the dead biomasses of *Azadirachta indica* swept away from households and unnecessarily buried in urban waste dumps could be recycled into ecological charcoal. But, it is necessary to know the binder best suited to better recovery in order to produce high-performance ecological charcoal for cooking. Thus, in this study, its valuation as cooking energy aims to determine the performance of organic and inorganic binders for the production of combustible ecological charcoal based on the dead biomass of *Azadirachta indica*. The collection and sorting of these plants made it possible to prepare the raw material and the binder. The mechanical method allowed the production of ecological coal by way of carbonization. Their physical and chemical characterization made it possible to respectively obtain the average density which is 1.13 ± 0.02, the average moisture content which is 3.17 ± 0.04%, the average of volatile matter content which is 46.92±1.93%, while the average fixed carbon content is 10.28±1.04%. The energy efficiency of the charcoals show that average calorific value which is 30.83 ± 1.08 MJ / Kg, an average maximum temperature of 540.37 ± 11.53 °C and a heat of the ash post combustion 262.95±18.37°C. The cooking test shows that with ecological charcoal based on *Azadirachta indica* (80%) bound to organic matter (20%), the average start of boiling of water is 6.38 ± 1.76 minutes while the average boiling time of water is interesting with ecological charcoal based on *Azadirachta indica* (90%) bound to inorganic matter (10%) of 12.8 ± 0.25 minutes.

**Keywords:** Ecological Charcoal, Organic Binders, Inorganic Binders, Biomass, *Azadirachta indica*

## INTRODUCTION
In the Sahelian zone of Cameroon, firewood is the only source of energy accessible by more than 80% of rural and urban households (Folefack and Abou, 2009). In 2002, the supply of firewood to the major cities of northern Cameroon was estimated at more than 50,000 tons per year (Njomgang, 2002). In terms of energy, the overexploitation of wood energy has caused a widening of the circle of deforestation around the towns of Maroua and Garoua, leading to erosion and a drop in agricultural productivity (Madi, et al., 2003; Folefack and Abou, 2009). However, in urban areas, the share of debris and waste from dead plants is estimated at 79.02 kilograms per day, with little "value" in the eyes of households, and which could be recycled into ecological charcoal (Dzokom, et al., 2022). One of the problems is knowing the most suitable binder for the production of ecological charcoal fuels based on the dead biomass of carbonized *Azadirachta indica* in order to make the by-products of the process profitable for the environment. *Azadirachta indica*, a species mainly planted in Sahelian towns, with an average defoliation of 1.28 kg/day (Tizé et al., 2013), has been described by the World Health Organization (WHO) as "the tree of 21st century" (IUCN, 2022). The dead stems of *Sorghum* sp., the dead stems of *Zea mays* L., the sap of *Acacia seyal* and the peels of *Saccharum officinarum* are organic binders on the one hand, while the sand from the dunes, the sand from the rivers, the monmorillonitic clay, and kaolinitic clay are inorganic binders whose effectiveness would allow better use. The objective of this work is to contribute to the determination of the performance of organic and inorganic binders for the production of ecological charcoal fuels based on the dead biomass of *Azadirachta indica*. Through a simple manual sorting, the inputs were selected and then prepared separately in order to obtain carbonized raw material and binder. The production of ecological coal followed by their physical and chemical characterization makes it possible to determine and control their physical state. Determining their energy efficiency through combustion tests makes it possible to classify binders for intensive production and less expensive use for households.

# 1. MATERIALS AND METHODS

## 1.1. Study zone

The city of Maroua, capital of the Far North region of Cameroon is located at an altitude of 423 m, between 10°29' to 10°41' North latitude and 14°15' to 14°27' East longitude. It is a linear city extending over 15 km in the direction of the West-East slope and covering 56 km² (Bouba, 2009). The Far North region, bordering Chad and Nigeria, covers an area of 34,263 km². The region belongs to the Sudano-Sahelian and Sudano-Guinean zones (MINEPAT, 2010; MINFOF, 2014). Five types of units are distinguished:

- the Logone alluvial plain which extends from Yagoua to Lake Chad is made up of sandy clay soils and vertisols on which we find woody vegetation dominated by *Acacia*
seyal, *Acacia siberiana*, Daniela olivieri, Ficus mitrgyna, Ziziphus mauritiana and Sesbania sesban;

- the vast plains of Diamaré, Bénoué, Kaélé, and Kalfou characterized by vertisols and ferruginous soils with a sandy-clay texture. Woody vegetation includes *Acacia seyal*, *Balanites aegyptiaca*, *Guiera senegalensis*, *Sterculia setigera*, *Anogeissu sleiocarpa*, *Vitellaria paradoxa* and *Lannea humilis*. The Bénoué plain is much more wooded with Combretaceae, Caesalpiniaceae, *Terminalia spp.*, *Khaya senegalensis* and Daniella olivieri;

- the Mandara Mountains from 800 to 1400 m in altitude, made of lithosols and which carry vegetation dominated by *Ziziphus mauritania*, *Boswellia dalzielii* and *Annonas senegalensis*;

- the foothills, transition zone between the Mandara Mountains and the plains, whose vegetation consists of *Terminalia macroptera*, *Diospiros mespiliformis*, *Annona senegalensis* and *Acacia albida*;

- woody formations (with *Prosopis spp.*, *Acacia seyal*, *Mitragyna inermis*) rupicolous located in permanent waterways (Bénoué, Logone) and large mayos such as Serwel, Mayo-Nguéchéwé, Mayo-Tsanaga, Mayo-Boula, Mayo Louti.

## 1.2. Selection, sorting and preparation of dead leaves and leaf stems of Azadirachta indica

Dead biomass of *Azadirachta indica* was collected in bulk from their dumping grounds. Then, via a manual selective sorting process, it was separated from the dead leaves on the one hand and the branches on the other. Then, after drying, a total of 10 kilograms of dry biomass was obtained, i.e.:

<table><caption>Table 1: Preparation of raw materials</caption><thead><tr><td>Raw material</td><td>Quantity after drying (gr)</td><td>Quantity after carbonization (gr)</td></tr></thead><tbody><tr><td><b><em>Azadirachta indica</em></b> dry dead leaves</td><td>500</td><td>159.3</td></tr><tr><td><b><em>Azadirachta indica</em></b> dry branches</td><td>500</td><td>165.9</td></tr></tbody></table>

The total amount of charred raw material used in this study is 300 grams, consisting of charred *Azadirachta indica* dead leaves (150 grams) and charred *Azadirachta indica* dead branches (150 grams).

## 1.3. Selection, sorting and preparation of binders

The organic binders used in this work are: dead stems of *Sorghum sp.*, dead stems of *Zea mays* L., Sap of *Acacia seyal* and peels of *Saccharum officinarum*. The inorganic binders used in this work are: Sand from the dunes, Sand from the rivers, monmorillonitic clay, and kaolinitic clay
<table><caption>Table 2: Preparation of binder materials</caption><thead><tr><th colspan="4">Organic binders</th><th colspan="4">Inorganic binders</th></tr><tr><th>Binder material</th><th>Fine quantity (0.2≤Ø≤1 ) (gr)</th><th>% Solution concentration</th><th>Viscosity (mPa.S)</th><th>Binder material</th><th>Fine quantity (0.2≤Ø≤1 ) (gr)</th><th>Plasticity index (Ip)</th><th>Swelling percentage (%)</th></tr></thead><tbody><tr><td>Stem Sorghum</td><td>100</td><td>20</td><td>1280</td><td>Dune sand</td><td>100</td><td>0-10</td><td>0-1</td></tr><tr><td>Stem Zea mays L.</td><td>100</td><td>15</td><td>2010</td><td>River sand</td><td>100</td><td>0-10</td><td>0-1</td></tr><tr><td>Acacia seyal sap</td><td>100</td><td>45</td><td>3000</td><td>Monmorillonitic red clay</td><td>100</td><td>10-20</td><td>1,5-5</td></tr><tr><td>Saccharum officinarum peel</td><td>100</td><td>05</td><td>2830</td><td>Kaolinitic clay from lowlands</td><td>100</td><td>10-20</td><td>1,5-5</td></tr></tbody></table>

## 1.4. Physical chemical characterization of fuel samples based on dry dead leaves of Azadirachta indica

### 1.4.1. Moisture content

Moisture content was inspired by the methodological measurement procedures developed by (Tobiasson, et Coll, 1991). Moisture content was expressed the water content and has a strong influence on the calorific value and the ignition capacity of the briquettes. The moisture content is obtained by the following formula:

$$W(\%) = \frac{(\text{Wet matter} - \text{Dry matter})}{\text{Dry matter}} \times 100 \quad (1)$$

With: W: moisture content; M wet: mass of the sample; M dry: mass obtained after heating to 105°C in an oven.

### 1.4.2. Density of charcoal

Kers et al., (2010) indicate that the density of cooking fuels based on bio-waste depends on the density of the original bio-waste, the pressure applied during the manufacture
of the cooking fuels and, by extension, the temperature and time. For this study, the formula was then established:

$$ \rho = \frac{m}{v} (gr/cm^3) \quad (2) $$

Where V is the volume of the briquette and m is the mass of the briquette.

### 1.4.3. Porosity of charcoal

The porosity of the briquettes, made in the laboratory, consists in determining the ratio between the volume of air present in the ground material (skeletal volume - apparent volume of the briquette) and the skeletal volume of the combustible briquette. Its formula is given by the relation:

$$ \alpha b = 1 - \frac{\rho_{app}}{\rho_{sq}} \quad (3) $$

With αb: porosity; ρapp: apparent density; ρsq: skeletal density

### 1.4.4. Charcoal Resistance Index

The Charcoal Resistance Index (CRI) or Green Coal Stability Test is determined by the compression tests that the green coal undergoes. The compressive strength of ecological coal in its cylindrical position is determined by the appearance of faults during its compression (Kers et al., 2010).

<figure><img src="image_36.png" /><figcaption>Figure 4: a)-Test of the compression force of briquettes and condition of appearance of cleavages; b) -Test of the axial compression force of briquettes and condition of appearance of cleavages (Kers et al., 2010).</figcaption></figure>

### 1.4.5. Fuel moisture uptake rate

The moisture uptake test via a simple immersion test that is subjected to ecological coal makes it possible to characterize their potential resistance to thermal and environmental hazards of the storage location. It consists of measuring the diameter of the fuel before and after immersion in order to determine the difference in water imbibition and the percentage of inclusion of the materials in the ecological charcoal briquette (Olorunnisola, 2007). It is expressed in cubic centimeters (cm³) (Dzokom et al., 2022).
### 1.4.6. Volatile matter content

The BS EN 14,774-1 protocol, for the determination of the volatile matter of a fuel consists in weighing the dry sample then heating it under nitrogen, at a temperature between 890° and 910°C for 7 minutes in a crucible with lid and weigh it again. The formula developed by the standard method (ASTMD3175-17, 2017) is used to calculate the volatile matter rate:

$$ M. O. V. = \frac{((M850^{\circ}C-M899^{\circ}C)\times100)}{Mdry} (\%) \quad (4) $$

With: MOV: Volatile matter content, M<sub>850°C</sub>: Mass obtained after heating to 895°C, M<sub>899°C</sub>: mass obtained after heating to 899°C

### 1.4.7. Ash content

In the context of this work, the ash content is the quantity of very small mineral matter contained in a fuel and released after complete combustion, under the effect of heat at high temperatures. The result is obtained by applying the formula developed by the standard methods (ASTMD5142-02, 2002 and ASTME711-87, 2004):

$$ A. = \frac{(M850^{\circ}C\times100)}{Mdry} (\%) \quad (5) $$

With: A, M<sub>850°C</sub>: mass of the powder obtained after incineration at 850°C, M<sub>dry</sub>: dry mass of the sample.

### 1.4.8. Fixed carbon content

To determine fixed carbon, the BS EN 14.774-1 protocol was used. Two parts, each weighing 1 gram, of combustible briquettes were made, then they were introduced into an oven for calcination. One part was calcined for 10 minutes at a temperature of 550°C, while the other part was calcined for 10 minutes at a temperature of 850°C. The fixed carbon rate developed by the standard method (ASTME711-87, 2004) allows it to be calculated using the following formula:

$$ C_f(\%) = 100 - (Hsec + Mce850^{\circ}C + Mv550^{\circ}C) \quad (6) $$

### 1.4.9. Fuel efficiency tests

#### a) Calorific value

The ASTME711-87 (2004) method and the MA protocol, 108-P.Cal. 1.0 helped measure and calculate calorific value. The heat capacity of the bomb and the tank was calculated from a test made with benzoic acid. The calorific value of the samples is measured by the following equation:

$$ P.C. = \frac{([1000 \times (T^{\circ}f - T^{\circ}i) \times W - (Hh \times a)])}{b} (MJ/kg) \quad (7) $$

Where P.C.: calorific value of the sample (MJ/kg); T°f: maximum final temperature of the water in the tank after firing (°C);

#### b) Determination of the ease of ignition of charcoal

The ignition test consists of determining the ease of ignition of combustibles in 5 minutes. It consists in measuring, using a thermocouple, the temperature of the fire of
an incandescent sample (T°it). The ignition of the fuel lasts 1 minute and the measurement of the temperature of the incandescent part of the fuel is done at 25 s (T°t') and at 300 s (T°t''). Ease of ignition is written by Formula 1 (Souleymane et al., 2020).

$$T^{\circ}it = T^{\circ}t'' - T^{\circ}t' \qquad (8)$$

T°it: ignition temperature, T°t'': temperature at t equal to 5 min, T°t': temperature at t equal to 25 s.

### c) Determination of the duration of combustion

The burning time (CD) test consists of determining the total burning time of 600 g of fuels introduced into an improved hearth with a clay combustion chamber. It begins with lighting until the ashes are obtained. The burning time is written according to Formula 2.

$$\Delta t = tf - ti \qquad (9)$$

Δt: time taken by the fuels to be consumed; tf: fuel combustion end time; ti: sample combustion start time

### d) Cooking test

The cooking test lasts 2 hours. It is determined from the onset and duration of water boiling, the quantities of water remaining and evaporated and then the fire temperature of the fuels. The results are obtained according to the relationships below:

#### Start of boiling

The onset of water boil is the time it takes for water to boil. It is expressed as follows

$$teb = t deb - t p \qquad (10)$$

teb: start of water boiling; t deb: time from which the water boils; t p: time from which the pan is placed on the fire.

#### Boiling time

It corresponds to the boiling time of water. To do this, we make the difference between the time when the water stops boiling and the time it starts boiling. The expression is as follows

$$\Delta t = t feb - t deb \qquad (11)$$

Δt: boiling time of water (min); t feb: end of water boiling; t deb: start of water boiling.

#### Amount of water remaining

The amount of water remaining corresponds to the mass of water remaining in the pan after the boiling test. It is written according to Equation 5.

$$Qr = Qi - Qf \qquad (12)$$

Qr: amount of remaining water (gr); Q i: the initial mass of water + that of the saucepan; Qf: the final mass of water + that of the saucepan.

#### Amount of water evaporated

The amount of evaporated water is the mass of water that evaporates during boiling. To obtain it, we take the difference between the initial mass of water and the remaining mass of water.
$$Q_v = Q_i - Q_r \qquad (13)$$

Q v: amount of water evaporated; Q r: amount of remaining water; Q i: the initial mass of water + that of the saucepan.

## f) Heat of post-combustion ash

It corresponds to the temperatures maintained in the ash after 30 minutes of end of fuel combustion. To do this, we take the temperature after 30 minutes from the end of combustion.

# 2. RESULTS AND DISCUSSION

## 2.1. Physical characterization of charcoal

Table 3 shows the overall physical parameters of the samples of ecological charcoal based on *Azadirachta indica* (90%) bound to inorganic matter (sand (10%) or clay (10%))

<table><caption>Table 3: Physical parameters of samples of ecological charcoal based on *Azadirachta indica* (90%) bound to inorganic matter (sand (10%) or clay (10%))</caption><thead><tr><th>Physical parameters</th><th>Moisture content (%)</th><th>Density (gr/cm³)</th><th>Porosity</th><th>Resistance index (%)</th><th>Moisture uptake rate (%)</th></tr></thead><tbody><tr><td>TOTAL AVERAGE</td><td>8.40±5.07</td><td>0.91±0.43</td><td>0.48±0.83</td><td>27.12±12.53</td><td>18.03±9.04</td></tr></tbody></table>

However, ecological charcoal based on *Azadirachta indica* (85%) linked to inorganic matter (sand (15%) or clay (15%)) has an average moisture content of 12.62 ± 0.50%, an average density of 1.04±0.04gr/cm³, an average porosity of 1.22±0.13, an average resistance index of 32.95±1.64%, and a moisture absorption rate (18.29±1.41%). The ecological charcoal based on *Azadirachta indica* (85%) bound to clays (Monmorillonitic red clay (15%) or Kaolinitic clay of lowlands (15%)) have an average moisture content of 6.04 ± 1, 17%, an average density of 1.15±0.03gr/cm³, with a low average porosity of -0.43±0.03, an average resistance index of 31.11±0.007%, and a recovery rate humidity 25.96±2.10%.

Table 4 shows the overall physical parameters of the samples of ecological charcoal based on *Azadirachta indica* (90%) bound to organic matter (*Sorghum sp.* stem (10%), or *Zea mays* L. stem (10%), or *Sap of Acacia seyal* (10%) or *Saccharum officinarum* peel (10%)).

<table><caption>Table 4: Physical parameters of samples of ecological charcoal based on *Azadirachta indica* (90%) linked to organic matter (*Sorghum sp.* stem (10%), or *Zea mays* L. stem (10%), or *Acacia seyal* sap (10%) or *Saccharum officinarum* peel (10%)).</caption><thead><tr><th>Physical parameters</th><th>Moisture content (%)</th><th>Density (gr/cm³)</th><th>Porosity</th><th>Resistance index (%)</th><th>Moisture uptake rate (%)</th></tr></thead><tbody><tr><td>TOTAL AVERAGE</td><td>3.17±0.04</td><td>1.13±0.02</td><td>0.67±0.03</td><td>73.96±3.29</td><td>1.43±0.19</td></tr></tbody></table>
The ecological charcoal based on *Azadirachta indica* (90%) bound to the stems of cereals (Stem *Sorghum* sp. (10%), or Stem *Zea mays* L. (10%)) have an average moisture content of 3.17 ±0.07%, an average density of 1.14±0.03gr/cm³, an average porosity of 0.66±0.04, an average resistance index of 74.32±2.87%, and a rate average humidity recovery of 1.33 ± 0.21% while the ecological charcoal based on *Azadirachta indica* (80%) linked to the saps of *Acacia seyal* (20%) or the peels of *Saccharum officinarum* (20%)) have an average moisture content of 3.18±0.007%, an average density of 1.13±0.02gr/cm³, an average high porosity of 0.69±0.03, an average resistance index of 73.6±4.86%, and a moisture uptake rate of 1.54±0.15%.

<figure><img src="image_37.png" /><figcaption>Graph 1: Major global physical parameters of ecological charcoal based on *Azadirachta indica* (80%) linked to organic matter (20%) and inorganic matter (20%)</figcaption></figure>

Among the samples of ecological charcoal based on *Azadirachta indica* (80%) bound to inorganic matter (20%), those of *Azadirachta indica_ Kaolin Clay* have an average density of 1.18 ± 0.94 gr/cm³ higher to that of charcoal (0.21) [9] and a low average resistance index of 31.11 ± 0.31%. Among the samples of ecological charcoal based on *Azadirachta indica* (90%) bound to organic matter (10%), those of *Azadirachta indica_ Stem of Sorghum sp.* have a high average density of 1.17 ± 0.02 gr/cm³ higher than that
of wood charcoal (0.2 to 0.6) (Badea et al., 2008) but the best average resistance index of 77.04 ± 0.73% is that of *Azadirachta indica* Sap of *Acacia seyal* (Gum Arabic).

## 2.2. Chemical characterization

Table 5 shows the overall chemical parameters of the samples of ecological charcoal based on *Azadirachta indica* (80%) bound to inorganic matter (sand (20%) or clay (20%)).

<table><caption>Table 5: Chemical parameters of ecological charcoal based on *Azadirachta indica* (80%) linked to inorganic matter (sand (20%) or clay (20%))</caption><thead><tr><th>Chemical parameters</th><th>Volatile Matter content (%)</th><th>Ash content (%)</th><th>Fixed carbon content (%)</th></tr></thead><tbody><tr><td><em>Total average</em></td><td>29.46±13.16</td><td>5.87±3.94</td><td>10.57±4.85</td></tr></tbody></table>

However, ecological charcoal based on *Azadirachta indica* (80%) linked to sands (dune sand (20%) or river sand (20%)) has an average volatile matter content 34.84 ± 2.92 %, an average ash content of 9.35 ± 0.52%, an average fixed carbon content of 13.12 ± 0.82, while the ecological charcoal based on *Azadirachta indica* (80%) linked to clays (Monmorillonitic red clay (20%) or lowland kaolinitic clay (20%)) have an average volatile matter content of 34.66±3.60%, an average ash content of 3.34±0.04 %, an average fixed carbon content of 11.63±0.48%.

Table 6 shows the overall chemical parameters of ecological charcoal based on *Azadirachta indica* (90%) linked to organic matter (Sorghum sp. stem (10%), or Zea mays L. stem (10%), or sap of *Acacia seyal* (10%) or *Saccharum officinarum* peel (10%)).

<table><caption>Table 6: Chemical parameters of samples of ecological charcoal based on *Azadirachta indica* (90%) linked to organic matter (Sorghum sp. stem (10%), or Zea mays L. stem (10%), or *Acacia seyal* sap (10%) or *Saccharum officinarum* peel (10%))</caption><thead><tr><th>Chemical parameters</th><th>Volatile Matter content (%)</th><th>Ash content (%)</th><th>Fixed carbon content (%)</th></tr></thead><tbody><tr><td><em>Total average</em></td><td>46.92±1.93</td><td>1.24±0.03</td><td>10.28±1.04</td></tr></tbody></table>

Ecological charcoal based on *Azadirachta indica* (80%) linked to the stems of cereals (Stem *Sorghum* sp. (20%), or Stem *Zea mays* L. (20%)) have an average volatile matter rate of 47.83 ± 1.20%, an average ash content of 1.23 ± 0.02%, an average fixed carbon content of 9.73 ± 0.71% while the ecological charcoal based on *Azadirachta indica* (90%) linked to the saps of *Acacia seyal* (10%) or the peels of *Saccharum officinarum* (10%)) have an average volatile matter content of 46.01 ± 2.54%, an average ash content of 1.26 ± 0.03%, an average fixed carbon content of 10.82±1.26%.
<figure><img src="image_38.png" /><figcaption>Graph 2: Overall chemical parameters of samples of ecological charcoal based on *Azadirachta indica* (80%) linked to organic matter (20%)</figcaption></figure>

Among the samples of ecological charcoal based on *Azadirachta indica* (90%) bound to organic matter (10%), those based on *Azadirachta indica_Stem Zea mays* L. have a high average volatile matter content of 48.69 ± 1.45% higher than that of charcoal between [12-15] (% (Badea et al., 2008). Ecological charcoal based on *Azadirachta indica* (80%) + River sand (20%) has the highest average fixed carbon rate is 13.71 ± 0.55%, lower than that of the French charcoal standard wood which is 65% (NF 444_NF, 2019). The ecological charcoal based on *Azadirachta indica* (80%) + Dune sand (20%) has a higher
ash rate of 9.72 ± 0.67% higher than that of charcoal (4.26 ± 1.64%) and lower than that of Typha_Arge coal which is 37.68 ± 0.97% (Kévin et al., 2016).

## 2.3. Energy efficiency

Table 7 shows the overall energy efficiency of ecological charcoal based on *Azadirachta indica* (80%) linked to inorganic matter (sand (20%) or clay (20%)).

<table><caption>Table 7: Overall energy efficiency of ecological charcoal based on *Azadirachta indica* (80%) linked to inorganic matter (sand (20%) or clay (20%))</caption><thead><tr><th>Energy efficiency parameters</th><th>Calorific value (MJ/Kg)</th><th>Combustion time (minutes)</th><th>Ignition time (secondes)</th><th>Post-combustion ash heat (°C)</th><th>Maximum temperature during combustion (°C)</th></tr></thead><tbody><tr><td><strong>AVERAGE TOTAL</strong></td><td>24,01±10,53</td><td>304,75±142,91</td><td>11,16±5,81</td><td>112,56±55,29</td><td>274,98±130,40</td></tr></tbody></table>

However, ecological charcoal based on *Azadirachta indica* (80%) linked to sands (Dune sand (20%) or River sand (20%)) have an average calorific value of 26.61±3.06 MJ/Kg, an average charcoal combustion time of 379.65±16.65 minutes, an average ignition delay of 15 seconds, a post-combustion ash heat of 127±1.41°C and a maximum temperature during combustion 319 ± 9.89 °C while ecological charcoal based on *Azadirachta indica* (80%) bound to clays (monmorillonitic red clay (20%) or lowland kaolinitic clay (20%)) have an average calorific value of 30.58±0.65 MJ/Kg, average charcoal burning time of 336.46±1.76 minutes, average ignition delay of 11 seconds, post-combustion ash heat of 146.5± 2.12°C and a maximum temperature during combustion of 341.5±0.70°C.

Table 8 shows the overall energy efficiency of ecological charcoal based on *Azadirachta indica* (90%) linked to organic matter (*Sorghum* sp. stem (10%), or *Zea mays* L. stem (10%), or Sap of *Acacia seyal* (10%) or *Saccharum officinarum* peel (10%)).

<table><caption>Table 8: Overall energy efficiency of samples of ecological charcoal based on *Azadirachta indica* (90%) linked to organic matter (*Sorghum* sp. stem (10%), or *Zea mays* L. stem (10%), or *Acacia seyal* sap (10%) or *Saccharum officinarum* peel (10%)).</caption><thead><tr><th>Energy efficiency parameters</th><th>Calorific value (MJ/Kg)</th><th>Combustion time (minutes)</th><th>Ignition time (secondes)</th><th>Post-combustion ash heat (°C)</th><th>Maximum temperature during combustion (°C)</th></tr></thead><tbody><tr><td><strong>AVERAGE TOTAL</strong></td><td>30.83±1.08</td><td>475.75±13.32</td><td>13.25±1.5</td><td>262.95±18.37</td><td>540.37±11.53</td></tr></tbody></table>

However, ecological charcoal based on *Azadirachta indica* (90%) bound to stems of *Sorghum* sp. (10%), or to stems of *Zea mays* L. (10%), have an average calorific value of
30.87±0.14 MJ/Kg, an average fuel combustion time of 475.06±17.52 minutes, an average ignition time of 12 seconds, a post-combustion ash heat of 264.04±13.13°C and a maximum temperature during combustion of 534.93±16.58°C while the eco-friendly carbon based on *Azadirachta indica* (90%) bound with the sap of *Acacia seyal* (10%) or the peel of *Saccharum officinarum* (10%) have an average calorific value of 30.79±1.87 MJ/Kg, a combustion time average combustibles of 476.44±14.94 minutes, an average ignition time of 14.5±0.70 seconds, an ash post-combustion heat of 261.87±28.9°C and a maximum temperature during of combustion 545.81±2.39°C.

<figure><img src="image_39.png" /><figcaption>Graph 3: Parameters Overall energy efficiency of samples of ecological charcoal based on *Azadirachta indica* (80%) linked to organic matter (*Sorghum sp. stem* (20%))</figcaption></figure>
Among the samples of ecological charcoal based on *Azadirachta indica* (90%) bound to organic matter (10%), those based on *Azadirachta indica* Sap of *Acacia seyal* (gum Arabic) have a high average calorific value of 32.12 ± 1.33 MJ/Kg, higher than that of charcoal which is 28.7 MJ/Kg and then that of Typha-Gum Coal which is 17.75 MJ/Kg C (Kévin et al., 2016), and the highest ash heat for ecological charcoal based on *Azadirachta indica* (90%) Acacia seyal sap which is 282.31 ± 03.16°C. Ecological coal based on *Azadirachta indica* + Stem *Sorghum sp.* has an average maximum temperature during the highest combustion which is 546.66 ± 02.23°C. The ecological charcoal based on *Azadirachta indica* Stem Zea mays L. has a high combustion time of 48.67 ± 02.22 minutes while the charcoal based on *Azadirachta indica* (80%) Monmorillonitic Red Clay (20%) and those based on *Azadirachta indica* (80%) Lowland Kaolinitic Clay (20%) have a low flammability after 11 seconds similar to those of Typha Charcoal - Clay obtained by Kévin et al., (2016).

## 2.4. Cooking test

Table 9 shows the overall parameters of ecological charcoal based on *Azadirachta indica* (80%) bound to inorganic and organic matter (20%).

<table><caption>Table 9: Cooking test with samples of ecological charcoal based on *Azadirachta indica* (80%) bound to inorganic and organic matter (20%).</caption><thead><tr><td>Cooking test parameters</td><td>Start of boiling (minutes)</td><td>Duration of boiling (minutes)</td><td>Amount of water remaining (liters)</td><td>Amount of water evaporated (liters)</td></tr></thead><tbody><tr><td>Average</td><td>7.62±2.05</td><td>14.08±1.41</td><td>0.41±0.15</td><td>0.6±0.15</td></tr></tbody></table>

When cooking with samples of ecological charcoal based on *Azadirachta indica* (80%) bound to inorganic matter (20%), the average onset of water boiling is 8.86±1.61 minutes, the average boiling time of water is 12.80±0.45 minutes. At the end of cooking, the average quantity of remaining water is 0.36±0.11 liter and the quantity of evaporated water 0.65±0.08 liter when the initial water is 01 liter.
<figure><img src="image_40.png" /><figcaption>Graph 4: Baking test parameters</figcaption></figure>

In addition, the cooking test with ecological charcoal based on *Azadirachta indica* (80%) linked to organic matter (20%) has an average start of water boiling of 6.38 ± 1.76 minutes while the average boiling time of water is interesting with ecological charcoal based on *Azadirachta indica* (90%) bound to inorganic matter (10%) of 12.8 ± 0.25
minutes. At the end of cooking, the lowest average quantity of remaining water is 0.36±0.20 liters and the quantity of evaporated water 0.65±0.01 liters.

## CONCLUSION

The objective of this study is to determine the performance of organic and inorganic binders for the production of combustible ecological charcoal based on the dead biomass of *Azadirachta indica*. The energy efficiency of the fuels made it possible to determine that among the samples of ecological charcoal based on *Azadirachta indica* (90%) bound to organic matter (10%), those based on *Azadirachta indica_ Sap of Acacia seyal* (gum Arabic) have a high average calorific value of 32.12 ± 1.33 MJ/Kg and a higher post-combustion ash heat for ecological charcoal based on *Azadirachta indica_Acacia seyal* sap which is 282.31 ± 03.16°C. The ecological charcoal based on *Azadirachta indica_ Stem *Sorghum* sp. has an average maximum temperature during combustion, the highest, which is 546.66 ± 02.23°C. The ecological charcoal based on *Azadirachta indica_ Stem *Zea mays* L. has a high combustion time of 48.67 ± 02.22 minutes while the charcoals based on *Azadirachta indica* (80%) _Monmorillonitic red clay (20%) and those based on *Azadirachta indica* (80%) + Kaolinitic clay of the lowlands (20%) have a low flammability after 11 seconds.

During the cooking test with ecological charcoal based on *Azadirachta indica* (80%) linked to organic matter (20%), the average start of boiling of water is 6.38 ± 1.76 minutes while the average boiling time of water is interesting with ecological charcoal based on *Azadirachta indica* (90%) linked to inorganic matter (10%) of 12.8 ± 0.25 minutes because, at the end of cooking, the lowest average remaining amount of water is 0.36±0.20 liters and the amount of evaporated water 0.65±0.01 liters.

The performance of the binders being linked to that of combustible ecological charcoal based on the dead biomass of *Azadirachta indica*, the most efficient binders are the sap of *Acacia seyal* (gum Arabic), the stem *Sorghum sp.*, the stem *Zea mays L.* for binders from organic materials and monmorillonitic red clay and kaolinitic clay from lowlands for binders from inorganic materials

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EXERCISES AND CORRECTIONS ON THE STUDY OF THE
PERFORMANCE OF ORGANIC AND NON-ORGANIC
BINDERS FOR THE PRODUCTION OF ECOLOGICAL
COAL FUELS BASED ON DEAD BIOMASS OF
AZADIRACHTA INDICA

Here are some possible exercises with answers concerning the study of the
performance of binders for the production of ecological charcoal based on dead
biomass of *Azadirachta indica* (neem).

---

**Exercise 1: Identification of binder types**

**Question:** Classify the following types of binders into organic and non-organic binders, then explain how their chemical nature can influence the properties of eco-friendly coal.

- Starch

- Lime

- Seed mucilage

- Clay

- Molasses

**Correction:**

- **Organic binders** : Starch, seed mucilage, molasses.

- **Non-organic binders** : Lime, clay.

Organic binders tend to increase the energy density of coal by breaking down easily under heat, which improves combustion. Non-organic binders, on the other hand, provide more structural stability but can sometimes reduce the thermal reactivity of the product.
## Exercise 2: Calculation of coal yield

**Question:** Suppose 10 kg of dead Azadirachta indica biomass is used for charcoal production. If the carbonization process and the addition of binders give a yield of 25%, what is the weight of the coal produced?

**Correction:**

$$ \text{Weight of coal produced} = 10 \text{ kg} \times 0.25 = 2.5 \text{ kg} $$

The weight of the coal produced is therefore 2.5 kg.

## Exercise 3: Comparison of briquette resistance

**Question:** In an experiment, two types of briquettes were produced with an organic and a non-organic binder. The briquettes were then subjected to a compressive strength test. Type A (organic binder) has an average strength of 1.2 MPa, while type B (non-organic binder) has a strength of 2.1 MPa. Explain why these strength values differ and what type of binder seems to be more suitable for durable charcoal briquettes.

**Correction:**

Briquettes with the inorganic binder (Type B) exhibit higher strength, which can be attributed to the nature of inorganic binders which generally provide more structural strength. This makes briquettes more suitable for uses requiring durability and mechanical resilience.

## Exercise 4: Choice of Binders and Impact on the Environment

**Question:** List three organic binders and three non-organic binders that can be used to produce eco-friendly charcoal from dead *Azadirachta indica* biomass. Briefly discuss the environmental impact of each type of binder.

**Correction:**

- **Organic binders:** Corn starch, molasses, and vegetable oil.

**Environmental impact:** These binders are biodegradable and less polluting during combustion, but may be less mechanically resistant, requiring more frequent replacement.

- **Non-organic binders:** Clay, lime, cement.
**Environmental impact:** Although these binders strengthen the structure of the coal, their extraction and production can contribute to pollution, and they can leave mineral residues.

---

**Exercise 5: Calorific Value Analysis**

**Question:** A study compares the calorific value of briquettes made with organic and non-organic binders. Briquettes with organic binders have an average value of 18 MJ/kg, while those with non-organic binders are 15 MJ/kg. Explain why there might be a difference in calorific value between these two types of briquettes.

**Correction:**

Organic binders add additional carbon, which increases the energy density of the briquettes. As they decompose, these binders also provide more complete combustion and better heat transfer. Non-organic binders do not contribute directly to combustion and can sometimes reduce the calorific value by increasing the amount of mineral residue.

---

**Exercise 6: Water Resistance of Briquettes**

**Question:** An experiment tests the water resistance of briquettes with different types of binders. After 10 minutes of exposure to water, briquettes with a non-organic binder (clay) retain 90% of their mass, while those with an organic binder (molasses) retain 60%. What conclusion can we draw about the effectiveness of binders in wet conditions?

**Correction:**

Non-organic binders, like clay, provide greater moisture resistance and allow briquettes to retain their mass, making them more durable in humid environments. In contrast, organic binders are often water soluble and degrade more quickly, which can be problematic for storage and use in humid climates.

---

**Exercise 7: Measuring Ash Content**

**Question:** When burning briquettes, those with an organic binder produce an average of 5% ash, while those with a non-organic binder produce 15%. Describe the impact of ash content on energy efficiency and maintenance of combustion equipment.

**Correction:**
High ash content, such as in briquettes with inorganic binders, can reduce energy efficiency because the ash does not burn and cools the firebox. Additionally, ash accumulation requires regular maintenance of combustion equipment to prevent blockages. Organic binders, with a lower ash content, therefore improve combustion and reduce maintenance requirements.

---

## Exercise 8: Calculation of Production Cost

**Question:** If the cost of non-organic binders per 1 kg of briquettes is $0.50, while the cost of organic binders is $0.30 per 1 kg of briquettes, calculate the difference in cost to produce 100 kg of briquettes with each type of binder. What would be the most economical choice, and what other considerations might influence this choice?

**Correction:**

- **Cost with non-organic binders:** $100 \text{ kg} \times 0.50 \text{ USD} = 50 \text{ USD}$

- **Cost with organic binders:** $100 \text{ kg} \times 0.30 \text{ USD} = 30 \text{ USD}$

The production of briquettes with organic binders is therefore more economical, with a saving of 20 USD per 100 kg. However, other factors such as the durability of the briquettes, their calorific value and storage conditions may influence the final choice.
# CHAPITRE 3. PRODUCTION OF BIOETHANOL BASED ON EICHHORNIA CRASSIPES COMBINED WITH THE PULP OF THE RIPE FRUIT OF AZADIRACHTA INDICA

Alexis Dzokom<fnref n="1" />, Jules Balna<fnref n="2" />, Joël Tizé Koda<fnref n="3" />, Félix Watang Zieba⁴, Roger Djouldé Darman<fnref n="5" />

## ABSTRACT

The management of invasive plants such as *Eichhornia crassipes* and the fruits of *Azadirachta indica* on the banks of the waters of Lake Chad in the Far North of Cameroon remains a challenge to overcome. On the other hand, given the urgency of finding other sources of energy following the scarcity of fossil fuels, it becomes appropriate to turn to renewable energies obtained from lignocellulosic biomasses which constitute an opportunity to be seized as cooking energy. The objective of this study is to determine the ethanoic potential of the biomass of *Eichhornia crassipes* associated with the pulp of *Azadirachta indica*. Thus, the production of bioethanol from the biomass of *Eichhornia crassipes* associated with the pulp of *Azadirachta indica* was done by biochemical route which results in: physical pretreatment of the raw material, thermo-mechanical pre-hydrolysis chemical, alcoholic fermentation with Lactobacillus fermentum yeast in batch mode and distillation. Measuring the pH and volatile fatty acid (VFA) content in different fermented samples made it possible to determine the optimal conditions for better fermentation. During 135 hours of fermentation, with 1281.25±1.09 ml of initial raw material fermented, it was possible to obtain on average 675.47±1.02 ml/g of hydrated ethanol and 640.62 ±5.07 ml/g of CO2 with an average weight yield of 52.72±3.57%. Thanks to a yeast contribution of 2.5% relative to the dry matter and an L/S ratio = 20, the dosage of the distillate obtained after distillation of the fermented must by the chronometric method made it possible to determine the ethanoic concentration of the solutions studied which is on average 0.94±0.01% V/V of distillate per fermented biomass.

**Keywords:** Bioethanol, *Eichhornia crassipes*, *Azadirachta indica*, Fermentation, Cooking Energy

## INTRODUCTION

At the Twenty-eighth Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP28) held from November 30 to

<footnote n="1">¹Department of Environmental Sciences, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>

<footnote n="2">²,⁴Department of Geography, Faculty of Arts Letters and Social Sciences, University of Maroua, Cameroon</footnote>

<footnote n="3">³Department of Renewable Energy, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>

<footnote n="5">⁵Department of Agriculture Animal Husbandry and By-Products, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>
December 12, 2023, in Dubai, United Arab Emirates, a global consensus of States to make a transition away from fossil fuels. The IPCC (2022), in its Sixth Assessment Report, estimates that limiting warming to 1.5°C above pre-industrial levels requires that global greenhouse gas emissions be reduced by 43% here 2030 compared to 2019 levels and that a level of net zero global CO2 emissions is reached by the early 2050s. It is imperative to limit warming to 1.5°C in order to minimize losses and damages linked to climate for people and nature (IUCN, 2023). The increase in pollutant emissions from the combustion of fossil fuels in the atmosphere contributes significantly to global warming with the corollary having a significant impact on ecosystems. This is done via the release of CO2 mainly through the combustion of fossil fuels (Azad et al., 2015; Dharma et al., 2016.) In addition, the increasingly growing demand for oil and adverse effects such as resulting climate changes (Sabba et al., 2018; Bunthita et al., 2016), have led to the search for alternative energy sources with very little impact on the environment (Siti et al., 2017; Novidzro et al., 2013). Furthermore, ethanol, added to gasoline, improves fuel combustion, thereby reducing exhaust emissions of CO and unburned hydrocarbons (Charles et al., 1996). Compared to gasoline, bioethanol has a 35-40% lower energy content and 35% higher oxygen content, which results in cleaner combustion and lower toxic emissions (Marouf. 2020). Bioethanol helps reduce CO2 emissions by up to 80% compared to the use of gasoline, thus contributing to a more sustainable environment (Sofien, 2015).

*Azadirachta indica* is a forest, fodder and ornamental tree which has proven ecological and especially medicinal properties. The annual fruit production of a single tree 8m to 10m high varies from 20.5kg to 55kg in Sahelian countries (Radwanski, 1977) and from 37kg to 100kg (Ketkar, 1976; Saxena et al., 1989) in tropical countries. When mature, *Azadirachta indica* produces an average of 50 kg of sweet fruits annually (Formad, 2013), the pulp of which (48% of the total mass of *Azadirachta indica* fruits) remains unused. As a result, *Azadirachta indica* pulp therefore represents a significant quantity of biomass, which requires energy recovery.

*Eichhornia crassipes* is an invasive aquatic plant (Adjahatode et al., 2016) with harmful biological consequences on the aquatic ecosystem and human activities threatening fisheries, river transport, tourism, etc. (Fragoso, 2011). This state of affairs alters the physicochemical and organoleptic quality of the water then reduces fishing stocks (Adjahatode et al., 2016) by reducing the oxygen level in the water making aquatic ecosystems less fertile (Das et al., 2016); It then becomes urgent to find techniques for valorizing *Eichhornia crassipes* that respect the environment in a sustainable manner in all its forms. Furthermore, *Eichhornia crassipes* is a lignocellulosic aquatic plant composed of cellulose, hemicellulose and lignin, with promoter biomass as an energy source due to its rapid growth (Daniel et al., 2020). Other functional characteristics of *Eichhornia crassipes* are its high hemicellulose and cellulose content and low lignin content, which makes it an excellent feedstock for second-generation ethanol
production (Zhang et al., 2018) and very effective in several areas such as wastewater
purification (Aïna et al., 2012). Bioethanol from water hyacinth is a biofuel which could
today be the subject of significant industrial and environmental development given
that unlike biogas, bioethanol can be a fuel for engines (Ayissi et al., 2016) and is easily
conserved (Ben Chaabane, 2006).

Investigations have shown that *Eichhornia crassipes* has an ethanolic power by alcoholic
fermentation (Adjahatode et al., 2016) while the pulp of *Azadirachta indica*, very rich in
total sugars, can be transformed into bioethanol by alcoholic fermentation (Sabba et
al., 2018). It is in this context that this study was initiated and is essentially oriented
towards the experimentation of ethanol production processes (biofuel) from the
biomass of *Eichhornia crassipes* associated with the pulp of *Azadirachta indica* more
precisely the optimization of the fermentable power of the mixture of these two types
of biomass (which are also plant waste) and the determination of its ethanoic degree.

# I- MATERIALS AND METHODS

I-1) - Raw material acquisition area and characterization

Samples of *Eichhornia crassipes* were collected in the waters of Lake Chad in Makari, Logone and Chari in the Far North of Cameroon (12°33'45.98 north latitude and 14°26'51.3 east longitude, 1845 km²) (Figure 1).

The sampling areas for *Azadirachta indica* fruits during the period January-March 2023
are the same as those for *Eichhornia crassipes*.

Six indices were applied to determine the distribution of individuals of each species in
the study area: the average abundance-dominance index and the average recovery rate
(MR), the presence index of *Eichhornia Crassipes* (Pi), Shannon-Weaver Index (H'),
Evenness Index (R), Frequency of evenness of the species on site (%)

$$
Eichhornia \ Crassipes
$$
<figure><img src="image_41.png" /><figcaption>Figure 1: Raw material acquisition area</figcaption></figure>

## I-2) - Pretreatment of the raw material and characterization

After collection, the whole *Eichhornia crassipes* plants were dried in the shade at room temperature for 96 hours, then in the oven at 60°C for 48 hours until a constant weight was obtained. Subsequently, dry *Eichhornia crassipes* were crushed in an electric grinder (Italian Power EG500 2.5 CV) and then sieved through a medium-sized mesh of 850µm. to increase the contact surface area to improve the efficiency of analytical testing. In total, 05 kilograms of *Eichhornia crassipes* powder was obtained.

*Azadirachta indica* fruits were sorted based on skin color (preferably yellow) and appearance (fresh) to the touch, fallen from the tree between 24 and 48 hours (Sabba et al., 2018). The average weight and proportion of pulp and kernels were determined by weighing batches of 250 fresh and ripe *Azadirachta indica* fruits using a precision balance (0.001 grams). The mass of each element separated from *Azadirachta indica* fruits was determined by weighing after separation of the pulp from the stone in each batch of fresh *Azadirachta indica* fruits. Slow stirring (30 rpm) in a specific container made it possible to separate the seeds from the pulp. This pretreatment of *Azadirachta indica* fruit pulp residues made it possible to obtain 02 liters of pure *Azadirachta indica* pulp juice for 18 kilograms of fruit used. The removed seeds were cleaned in 04 lira.
This solution was added to 02 liters of pure *Azadirachta indica* fruit juice collected, which ultimately resulted in 06 liters. This solution was diluted in 30 liters to obtain a final solution concentrated at 1/5 (v/v).

The fiber content of the two raw materials is determined by differential gravimetry of the residues obtained after solubilization of the non-wall constituents (lipids, proteins and water-soluble, etc.), hemicelluloses and lignins. The dry matter was determined on a mass of 5 grams of each raw material, placed in an isothermal oven at 105°C until a constant mass was obtained (AFNOR, 1982). The total ash content was determined by calcination of the test portion used as dry matter, in a high temperature oven at 550 ± 15 °C (AFNOR, 1982).

## I-3) - Composition of samples of the raw material to be fermented

The test was conducted using a randomized Fisher block design comprising five (5) substrates which are:

- Control1 = 01 liters of *Eichhornia crassipes* substrate (100g/l);

- Control2 = 01 liters of *Azadirachta indica* fruit substrate (1/5 (g/l));

- Substrate 1 = 0.33 liters of *Eichhornia crassipes* substrate (100g/l) + 0.66 liters of *Azadirachta indica* fruit substrate (1/5 (g/l));

- Substrate 2 = 0.5 liters of *Eichhornia crassipes* substrate (100g/l) + 0.5 liters of *Azadirachta indica* fruit substrate (1/5 (g/l));

- Substrate 3 = 0.66 liters of *Eichhornia crassipes* substrate (100g/l) + 0.33 liters of *Azadirachta indica* fruit substrate (1/5 (g/l)).

<figure><img src="image_42.png" /><figcaption>**Photo 1: Samples of the raw material to be fermented**</figcaption></figure>

Five Bioreactors were prepared with the addition in each of them a volume of water in the respective proportions of 1/3, 1/4, 1/5, 1/6 and 1/7 of the volume of final solution, in order to obtain preliminary dilutions which aim to create environments favorable to bacterial growth during the next inoculation with yeasts.

## I-4) - Processing of the raw material

The treatment was carried out by subjecting *Eichhornia crassipes* powder to steam explosion which is a very promising technique for lignocellulosic biomass before bioconversion. It is a thermo-mechano-chemical process which destroys lignocellulosic material and partially hydrolyzes it (Cosme et al., 2018). This steam explosion process was developed by W. H. Mason in 1925 for the production of
hardboard (Wertz et al., 2016). It is composed of two distinct phases; steam cracking and explosive decompression (Eloutassi et al., 2014). 50g of *Eichhornia crassipes* powder is placed in an Erlenmeyer flask containing 0.5 liters of distilled water. 50 liters of *Eichhornia crassipes* substrate (concentrated at 100 g/l) was obtained. The substrate is pretreated with steam in an autoclave for 1 hour at 270°C. Samples were taken every 10 minutes to assess changes in sugar levels and glucose concentration.

Furthermore, a fraction of 500ml of the 12 liters of *Azadirachta indica* fruit juice collected is brought to the boil at 70°C for 60 minutes with continuous stirring following the method of Chniti et al. (2013). Then, the juice of *Azadirachta indica* fruit was filtered using muslin after cooling, then heated to 85°C for 20 minutes to eliminate the bacterial flora and cooled to room temperature following the methods of Diakabana et al. (2013) and Massengo et al. (2016). Finally, urea ($NH_2CONH_2$ 46% minimum) was added at a rate of 4 g/l to ensure optimal yeast growth and accelerate the fermentation kinetics (Novidzro et al., 2013; Gbohaida et al., 2016).

## I-5) - Alcoholic fermentation of the solution of *Eichhornia crassipes* associated with fresh fruits and blackberries of *Azadirachta indica*

### I-5-1) - Preparation of the inoculum

The protocol described by Massengo et al. (2016) was used to prepare the inoculum. The yeast is pre-inoculated when introducing 0.6 g of the dry yeast strain of *Lactobacillus fermentum* into 100 ml of distilled water, containing 44 ml of a 12% (v/v) sucrose solution, under continuous stirring for 90 minutes and at a temperature of 27°C (Gauthier et al., 2005).

### I-5-2) - Alcoholic fermentation

The prepared inoculum was added to the solution in the ratio Inoculum/Solution=1/500 (v/v) with continuous stirring during fermentation. The simultaneous saccharification and fermentation process used *Saccharomyces cerevisiae* (ATCC 9763), a commercial enzyme at 7 FPU/g dry mass. In each bioreactor, 0.1 liter of diluted solution after optimized pretreatment with acid was packaged in 50 ml samples coupled to a fermentation device in a pH 4.8 buffer solution. The hydrolysis process was initiated after initial volume gain of the solutions in the fermentation devices then subjected to constant stirring for 120 minutes at 80°C.

The process of enzymatic hydrolysis and separate fermentation which were carried out following conditions identical to the simultaneous hydrolysis and fermentation described by Daniel et al., (2020). The previously prepared enzyme inoculum was used in a buffer solution at pH 4.8. The hydrolysis process was started after measuring the volumes of the solutions in the fermentation devices and constantly stirring using a stirrer (HJ-1S, 1000ml, 0-1200 rpm) at 70°C for 24 hours of hydrolysis at a concentration of 2% of the total volume of the hydrolyzate. The fermentation devices after
inoculation were subjected to stirring at 300 rpm at 35°C for 30 hours in order to similarly determine the quantity of CO₂ produced during fermentation.

From the solutions obtained, 05 alcoholic fermentation tests were carried out following the process described by Sabba et al., (2018): 01 test where the pH of the solution was not adjusted (pH = 5.1) and 04 tests in which the pH of the solutions obtained were adjusted to 4.1, 4.3, 4.5 and 4.7 with a diluted sulfuric acid solution (H₂SO₄, 1.5N)). Once the desired pH is reached for the different adjusted solutions (4.1, 4.3, 4.5, and 4.7) and the unadjusted solutions, the latter are transferred to the 1 liter fermentation devices and carried out anaerobically for 120 hours (Ameyapoh et al., 2006), at a temperature of 30 ± 2°C (Boulal et al., 2013, 2010; Kaïdi and Touzi, 2001).

Fermentation monitoring was carried out by sampling 10 ml using a syringe every 24 hours and for 120 hours (Sabba et al., 2018). The data recorded are: pH, temperature and density of the fermentation must. At the end of alcoholic fermentation, the ethanol contained in the must is extracted by distillation at 78.5°C (Diakabana et al., 2016).

### I-5-3) - Alcohol content of the bioethanol obtained

Ethanol productivity was determined by direct measurement of the volume of the distillate obtained (after distillation) for each fermentation test (Sabba et al., 2018). The alcoholic degree was determined using the OIML method (1973), after distillation of the solutions following the various fermentation tests.

### I-5-4) - Statistical analysis

Each test was repeated 03 times for the physicochemical analyzes of the pulp and the physical characterization of the fruits of Azadirachta indica. The fermentation tests at different pH were carried out in two stages. The results obtained were expressed in the form: M±σ, with σ = the standard deviation and M the mean. A probability p<5% was considered a non-significant difference in the data analysis.

### I-5-5)-Weight yield

The weight yield is determined by the ratio between the quantity of alcohol produced and the quantity of substrate used. (Boulal et al., 2010). Knowing that 01 liter (100 cl) of pure alcohol weighs 800 grams and that 01 kilogram of glucose gives approximately 500 g of ethanol and 500 g of CO₂, in the context of this study, the weight yield which is the ratio of the mass of bioethanol to the mass of substrate used is calculated and expressed as follows:

$$ \text{Weight yield} = \frac{(\text{Quantity of alcohol})}{(\text{Quantity of substrate})} $$

With: Weight yield in %v/v or %g/g; Quantity of alcohol in ml or grams and quantity of substrate in ml or grams
## II-) - RESULTS

### II-1) - Taking floristic data on site

The floristic data of *Eichhornia Crassipes* over 20m² in plots of 01 m² were carried out in Makary: Point 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, a total of 10 points of data collection.

The production data of *Azadirachta indica* over 2500 m² in plots of 25 m² were carried out in Makary: Point 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, a total of 10 data collection points.

From 2022-2023, the harvest of *Eichhornia Crassipes* in Makary in the Lake Chad area allowed us to determine the average abundance-dominance index (3.5±1.3), the average recovery rate (RM =89±0.52%) and the average weight of the biomass (5.20±3.31 kg/day) while the harvest of *Azadirachta indica* fruits in Makary in the Lake Chad area allowed us to obtain the average abundance-dominance index (4.75±0.5), the average recovery rate (RM=84.37±2.85%) and the average biomass weight (0.41±0.20 kg/day)

<table><caption>Table 1: Estimation of spatial heterogeneity of biomasses</caption><thead><tr><th>Species studied</th><th>Period</th><th>Number of relief points</th><th>Weight of biomass studied (kg/period)</th><th>Number of individuals (Ri)</th><th>Average recovery (RM) %</th><th>Abundance-dominance indices</th></tr></thead><tbody><tr><td><i>Eichhornia Crassipes</i><br>Plants</td><td rowspan="2">June- May</td><td rowspan="2">10</td><td>467.75±297.83</td><td>1004±526.32</td><td>89±0.52</td><td>3.5±1.3</td></tr><tr><td><i>Azadirachta indica</i><br>Fruits</td><td>37.25±18.34</td><td>165±2</td><td>84.37±2.85</td><td>4.75±0.5</td></tr></tbody></table>

### II-1-1)-Presence of biomass in sampling sites

The diversity or specific richness of each environment in *Eichhornia Crassipes*, which takes into account both richness and fairness, was determined using the Shannon-Weaver index, the general average of which is 2.37 ±1.09, an average presence index of 0.19±0.14 with an average frequency of 24% and a Regularity Index (R) of 0.67±0.31. *Azadirachta indica* fruits collected on and under *Azadirachta indica* trees made it possible to determine a Shannon-Weaver index of 1.86±0.28 with an average presence index of 0.23±0.05, an average frequency of 9.33±2.31% and a Regularity Index (R) of 0.52±0.08.

<caption>Table 2: Quantification of species present on the sites</caption>
<table><thead><tr><th>Species studied</th><th>Presence index of Eichhornia Crassipes (Pi)</th><th>Shannon-Weaver index (H')</th><th>Regularity index (R)</th><th>Frequency of Eichhornia Crassipes (%)</th></tr></thead><tbody><tr><td><i>Eichhornia Crassipes</i> Plants</td><td>0.19±0.14</td><td>2.37±1.09</td><td>0.67±0.31</td><td>24±12</td></tr><tr><td><i>Azadirachta indica</i> Fruits</td><td>0.23±0.05</td><td>1.86±0.28</td><td>0.52±0.08</td><td>9.33±2.31</td></tr></tbody></table>

## II-2) - Physical characterization of the raw material

The morphological study of *Azadirachta indica* fruits and *Eichhornia Crassipes* plants allowed us to have their characteristics illustrated in the following Table. The results represent the average of each parameter on 30 batches of 100 fruits of *Azadirachta indica* and on 30 batches of 10 plants of *Eichhornia Crassipes*.

<table><caption>Table 3: Average results of physical analyzes</caption><thead><tr><th colspan="2">Azadirachta indica fruits</th><th colspan="2">Eichhornia Crassipes plants</th></tr></thead><tbody><tr><td>Fruit weight (g)</td><td>0.487±0.019</td><td>Plant weight (g)</td><td>0.752±0.001</td></tr><tr><td>Pulp weight (g)</td><td>0.359±0.004</td><td>Leaf weight (g)</td><td>0.382±0.046</td></tr><tr><td>Seed weight (g)</td><td>0.123±0.013</td><td>Stem weight (g)</td><td>0.253±2.231</td></tr><tr><td>Fruit short axis length (cm)</td><td>0.818±0.043</td><td>Leaf length (cm)</td><td>25.932±2.231</td></tr><tr><td>Fruit long axis lengths (cm)</td><td>1.781±0.067</td><td>Maximum stem lengths (cm)</td><td>32.230±1.654</td></tr><tr><td>Pulp/fruit ratio (%)</td><td>73.717±1.743</td><td>Leaf/plant ratio (%)</td><td>50.798±7.234</td></tr><tr><td>Seed/fruit ratio (%)</td><td>25.257±2.214</td><td>Stem/plant ratio (%)</td><td>33.643±6.170</td></tr><tr><td>Almond/fruit ratio (%)</td><td>10.921±0.039</td><td>Ratio (leaf + stem)/fruit (%)</td><td>84.441±4.894</td></tr><tr><td>Color</td><td>Yellowish</td><td>Color</td><td>Brown</td></tr></tbody></table>

The fruit of *Azadirachta indica* has an average length of approximately 1.781±0.067 cm. The thin skin and bittersweet pulp of the yellowish-white fruit is very fibrous and weighs on average 0.359±0.004g, representing on average 73.717±1.743% of the total fruit weight.
<figure><img src="image_43.png" /><figcaption>**Photo 2: Azadirachta indica fruit**</figcaption></figure>

The *Eichhornia Crassipes* plant has an average maximum stem length of approximately 32,230±1,654 cm while the average leaf length is 25,932±2,231 cm. The *Eichhornia Crassipes* plant weighs approximately 0.752±0.001g, and the aerial part of *Eichhornia Crassipes* (leaf + stem), very fibrous, represents on average 84.441±4.894% of the total weight of the plant. These proportions of material to be used are interesting for use in the fermentation process for the purposes of bioethanol production.

## II-3) - Chemical characterization of the raw material

The following table shows that the average rate of raw material is 85.67± 0.42 (g/100g) for *Azadirachta indica* fruits and 79.75±1.19 (g/100g) for *Azadirachta indica* plants.

<figure><img src="image_44.png" /><figcaption>**Photo 3: *Eichhornia Crassipes* plant**</figcaption></figure>

The average pH for *Azadirachta indica* fruits is 05.12±0.91 and 05.24±0.07 for *Eichhornia Crassipes* plants. This pH is harmful to the development of bacteria but it is favorable to the proliferation of yeasts and molds, Bocquet (1982) which is a positive point for alcoholic fermentation.
The fruit pulp of *Azadirachta indica* is woody (13.51±1.65 g/100g DM), with proportions of hemicellulose (17.87±1.21 g/100g DM) and 70.05±2, 32 g/100g DM of cellulose while the *Eichhornia Crassipes* plant is less woody (08.18±1.85 g/100g DM), with proportions of hemicellulose (27.87±0.23 g/100g DM) and 33.42±0.02 g/100g DM of cellulose

<table><caption>**Table 4: Result of chemical analysis of the raw material**</caption><thead><tr><th>Chemical parameters</th><th><i>Azadirachta indica</i> fruits</th><th><i>Eichhornia Crassipes</i> plants</th></tr></thead><tbody><tr><td>pH</td><td>05.12±0.91</td><td>05.24±0.07</td></tr><tr><td>Humidity rate (%)</td><td>38.11±3.76</td><td>46.07±1.21</td></tr><tr><td>Dry matter (g/100g)</td><td>85.67±0.42</td><td>79.75±1.19</td></tr><tr><td>Cellulose (g/100g DM)</td><td>70.05±2.32</td><td>33.42±0.02</td></tr><tr><td>Hemicellulose (g/100g DM)</td><td>17.87±1.21</td><td>27.87±0.23</td></tr><tr><td>Lignin (g/100g DM)</td><td>13.51±1.65</td><td>08.18±1.85</td></tr><tr><td>Reducing sugar content (g/100g DM)</td><td>74.75±5.07</td><td>67.21±2.01</td></tr><tr><td>Ether extract (g/100g MS)</td><td>05.01±0.02</td><td>35.01±1.65</td></tr><tr><td>Ash rate (g/100g DM)</td><td>07.31±0.29</td><td>166.25±0.29</td></tr></tbody></table>

These cellulose, hemicellulose and lignin contents found in this study are similar to the data described by Reales (2013) who proposed the production of ethanol from water hyacinth by pretreatment with sulfuric acid (2% v/v) and describes a considerable fraction of hemicellulose (21.33 g/100g DM) with a low lignin content (4.40 g/100g DM). The lignin presented by water hyacinth contributes to the lower crystallinity and the recalcitrance of the biomass to degrade during fermentation in order to release elements useful for the formation of bio-alcohol. Which directly reflects the better efficiency of the hydrolysis process and conversion of sugars into ethanol (Daniel et al., 2020).

Another interesting aspect is the concentration of carbohydrates (available reducing sugars which constitute the sum of the contents of Cellulose, Hemicellulose, Starch and total soluble sugars) i.e. a total of 74.75±5.07 g/100g DM of carbohydrates for *Azadirachta indica* fruits and 67.21±2.01 g/100g DM for *Eichhornia Crassipes* plants. These data reflect a stoichiometric projection of ethanol; which makes these raw materials an interesting product with high potential for the production of ethanol.

## II-4) - Proportionate mixtures of solution based on the fruits of *Azadirachta indica* with the solution based on *Eichhornia crassipes*

The randomized Fisher block device comprising the five (5) substrates which were constituted were arranged as follows:

<caption>**Table 5: Proportioned substrate mixtures**</caption>
<table><thead><tr><th></th><th>Control<br>Solution1<br>(liter)</th><th>Control<br>Solution2<br>(liter)</th><th>Solution1<br>(liter)</th><th>Solution2<br>(liter)</th><th>Solution3<br>(liter)</th></tr></thead><tbody><tr><td><i>Azadirachta indica</i> fruit juice diluted with water (1/5 v/v)</td><td>/</td><td>01</td><td>0.66</td><td>0.50</td><td>0.33</td></tr><tr><td>Fine particles of dry matter from <i>Eichhornia crassipes</i> plants diluted with water (100g/l)</td><td>01</td><td>/</td><td>0.33</td><td>0.50</td><td>0.66</td></tr></tbody></table>

Control Solution1 = 01 liter of *Eichhornia crassipes* solution (100g/l);

Control Solution2 = 01 liter of *Azadirachta indica* fruit solution (1/5 v/v);

Solution 1 = 0.33 liters of *Eichhornia crassipes* solution (100g/l) + 0.66 liters of *Azadirachta indica* fruit solution (1/5 v/v);

Solution 2 = 0.5 liters of *Eichhornia crassipes* solution (100g/l) + 0.5 liters of *Azadirachta indica* fruit solution (1/5 v/v);

Solution 3 = 0.66 liters of *Eichhornia crassipes* solution (100g/l) + 0.33 liters of *Azadirachta indica* fruit solution (1/5 v/v).

Each solution, including the control solutions, has an initial volume of 1 liter. Each solution consists of mixing *Azadirachta indica* fruit juice with fine particles of *Eichhornia crassipes* (obtained via the 850µm mesh sieve). The pretreatment of these solutions with steam in an autoclave for 01 hour at 270°C resulted in a first distillation, the results of which were as follows:

<table><caption>Table 6: Initial property of solutions</caption><thead><tr><th>Dilution number</th><th>Sugar content (g/100kg DM)</th><th>Density at 20°C</th><th>Alcohol content (%)</th></tr></thead><tbody><tr><td>Solution T<sub>1</sub></td><td>65.21±2.07</td><td>1.0370 ± 0.0014</td><td>7.5025 ± 0.4231</td></tr><tr><td>Solution T<sub>2</sub></td><td>69.68±5.11</td><td>1.0372 ± 0.0165</td><td>7.5056 ± 0.8962</td></tr><tr><td>Solution<sub>1</sub></td><td>72.62±4.82</td><td>1.0367 ± 0.01442</td><td>6.2637 ± 1.04052</td></tr><tr><td>Solution<sub>2</sub></td><td>71.25±3.76</td><td>1.0363 ± 0.0179</td><td>6.1787 ± 0.8764</td></tr><tr><td>Solution<sub>3</sub></td><td>71.29±4.65</td><td>1.0362 ± 0.0219</td><td>6.1218 ± 1.0067</td></tr></tbody></table>

According to the table 6 above, the mixture of solutions allows us to perceive a higher initial alcohol level in solution 1, while it is lower in solution T<sub>2</sub>.

## II-5)-Monitoring physicochemical parameters during fermentation

The results of the physicochemical analyzes of the solutions after addition of the inoculum during fermentation are presented as follows:

### II-5-1) - The pH

Determining pH is an essential step in controlling biological activity. The following graph indicates that the pH decreased from 4.60 to 4.56 during fermentation in control
solution 2 while it increased in all other solutions with a jump in pH between 5.45 and 6.85.

As pH is essential for controlling biological activity, the production medium was initially adjusted between 5.01 and 5.23. During alcoholic fermentation, the metabolism of the yeast induces a perpetual change of the environment. Thus the consumption of carbonaceous and nitrogenous substrates is accompanied by the production of metabolites of carboxylic acids or alcohols. The following graph shows a variation in the pH of the solutions during alcoholic fermentation.

<figure><img src="image_45.png" /><figcaption>Graph 1: Evolution of pH during fermentation</figcaption></figure>

For the solution based on *Azadirachta indica* fruit juice diluted with water (1/5 v/v), this phenomenon is entirely expected because the metabolic activity of the yeasts caused the variation in pH and made the more acidic environment due to the release of organic acids after the degradation of sugars by the action of the yeast used (Mehani et al., 2013; Tadmourt et al., 2020).
However, plant-based solutions of *Eichhornia crassipes* diluted with water (100g/l) have the same tendencies. The evolution of their pH as a function of fermentation duration presents the same oscillation for all solutions. The curve of the sample of control solution 1 (ST₁) (after addition of yeast = 3.5%) results in two peaks; one at 48 hours and the other at 76 hours while the curves of solutions S₁, S₂ and S₃ present peaks between 42 hours and 48 hours but do not present two peaks as well differentiated after 90 hours. The optimal pH range for yeast activity is between 4.6 and 6 (Le Blanc, 2008). Analysis of the results obtained shows that the pH values are between 4.21 and 7.94 during fermentation. These results therefore justify yeast activity in the environment.

## II-5-2) - Density

The following graph represents a remarkable decrease in the density of solutions ST₂, S₁, S₂ and S₃ during fermentation varying from 1.0064 to 1.0147 and corresponding to different pH values between 4.55-7.13, transitional between the acidic environment and the alkali environment.

<figure><img src="image_46.png" /><figcaption>Graph 2: Evolution of density during fermentation</figcaption></figure>
These variations can be explained by the transformation of glucose or fermentable sugars into alcohol and a strong loss of mass in the form of CO2 (Boulal *et al.*, 2016, 2017; Gaillard *et al.*, 1995).

## II-5-3) - Reducing sugars

The Graph 3 below shows after 87 hours of must fermentation. This is due to a significant degradation of the sugar which is intense during the first 36 hours, leading to a decrease in the values between 25.36%, 17.09%, 22.55% and 25.25% respectively for the ST₂, S₁, S₂ and S₃. However, in the ST₁ solution, there was rather an increase in the level of reducing sugar: which means the yeasts favored the formation of sugars.

Observation of the curve during the first 48 h indicates that hydrolysis was very slow in the four hydrolyzed samples (ST₂, S₁, S₂ and S₃). This can be justified by the establishment of the hydrolysis process by enzymes in the media. After 48 hours, some samples (ST₂ and S₂) are hydrolyzed more quickly than others, in particular sample S₂, which gives an interesting concentration (21.29 mg/ml) after 107 hours.
<figure><img src="image_47.png" /><figcaption>Graph 3: Evolution of the reducing sugar content during fermentation</figcaption></figure>

The S₁ solution does not release considerable glucose during hydrolysis. This principle is fundamental because complex sugars are broken down into simple sugars by the synergistic action of enzymes which can be defined by good coordination of hydrolysis (Cosme et al., 2018).

The three types of enzymes involved in the process are endo-1,4-glucanase and exo-1,4-glucanase cellulase, which hydrolyze celluloses to cellobiose, and β-glucosidases which hydrolyze cellobioses to glucose (Eloutassi et al., 2014; Kumar et al., 2008).

II-5-4) - Alcoholic degree
The following graph clearly shows that the alcohol content increased during fermentation and that the kinetics of alcohol production is related to the sugar content of the substrate in all solutions.

<figure><img src="image_48.png" /><figcaption>Graph 4: Evolution of the alcohol content during fermentation</figcaption></figure>

In the first 48 hours, the alcohol content is constantly increasing for all solutions. The lowest value of the alcoholic degree (4.24v/v) was observed for the S<sub>1</sub> solution while the highest alcoholic degree (8.84v/v) was observed in the ST<sub>2</sub> solution. On the other hand, alcohol production increases during the first 48 hours of fermentation. This result is in agreement with that reported by Boulal (2017) and Hadri (2023).

II-5-5) - Analyzes of the ethanolic power of the bioethanol produced

II-5-5-1) - Volatile Fatty Acid (VFA) Content
Bioethanol produced from *Eichhornia crassipes* plants combined with Azadirachta indica fruits is quite volatile, flammable, and clear has a pungent odor. The results obtained show that the evolution of Volatile Fatty Acid (VFA) contents as a function of fermentation duration also presents two peaks for all samples of all fermented solutions, with similar curves. From the start of fermentation, Volatile Fatty Acid (VFA) contents are observed in the medium ranging from 5.24 mg/g (ST₁) to 5.81 mg/g (S₁). This quantity of Volatile Fatty Acid at 0 hour represents more than 50% of the maximum production observed. During the first phase between 0h and 50h, the highest peak was reached by solution ST₁ is 7.32mg/g) while solution S₁ had only 8.14mg/g, lower than all the other solutions. During this first phase, the production of AGV increases then decreases until around 70 hours of fermentation of all solutions. This first growth could be explained by the principle of the initial decomposition of the ferment in the form of macromolecules (baker's yeast) into microorganisms (*S. cerevisiae*) (Flora et al., 2016).

During the second phase between 130 hours and 150 hours, the second highest peak was reached by solution ST₁ is 8.89mg/g) while solution S₁ had only 7.46mg/g, lower than all other solutions. For this sample S₁, the ratio between the initial and maximum production of Volatile Fatty Acid is more than 71.37% while for solution ST₁, the ratio between the initial and maximum production of Volatile Fatty Acid is more than 58.94%.

This spontaneous reaction demonstrates that pretreatment accelerates decomposition and facilitates enzymatic activity (Flora et al., 2016).
<figure><img src="image_49.png" /><figcaption>Graph 5: Volatile Fatty Acid Content of solutions as a function of fermentation duration</figcaption></figure>

After 74 hours, the resumption of growth results in ascending curves which reach their optimum between 122 hours and 145 hours for all samples. This very pronounced second growth is favored by the fermentation of the substrate by all the microorganisms present in the medium (Flora et al., 2016). Practically, the same results
were obtained from the three tests of the experiment. The quantity of VFA produced varies depending on the three parameters studied: the volume of water, the quantity of yeast and the duration of fermentation.

## II-5-5-2)- Influence of the quantity of ferment and the duration of fermentation

The yeast used here is *Lactobacillus fermentum*, widely used in the production of dolo, a fermented drink made from the substrate of *Sorghum sp*. The volatile fatty acid (VFA) contents as a function of the fermentation duration of the samples of solutions ST₁, ST₂, S₁, S₂ and S₃ influenced by the addition of 0.5 g (2.5%), 1 g (5%), 1.5 g (7.5%), 2 g (10%) and 2.5 g (12.5%) of yeast are shown in the following graph 6. The optimal fermentation time is equal to 135 hours. On the other hand, for the hydrolyzed heterogeneous mixture samples S₁, S₂, and S₃, the production of VFA evolves between 0 and 135 h. We will therefore use an optimal fermentation time of 135 hours. The curves have the same appearance.

Furthermore, the samples from batches "b", "c", "d" and "e" having had a yeast content greater than 1 g reach their maximum VFA production more quickly than the samples which had no yeast content. This variation follows the principle according to which the provision of enzymatic activity is necessary and makes it possible to accelerate the fermentation of lignocellulosic biomasses (Flora et al., 2016, Almoustapha et al., 2008). Thus, the choice would be a maximum yeast level for good fermentation. But this rate must be limited, or even minimized, for socio-economic reasons: better valorization of biomass at low cost (Flora et al., 2016).

The analysis of the results of the first "a" batch is in line with those obtained by Flora et al. (2016) and Fragoso (2011) who found an optimal duration of 120 and 121 hours respectively for the fermentation of water hyacinth. The use of *S. cerevisiae* NBRC 2346 required a fermentation time of 96 hours (Mishima et al., 2008).

We can therefore conclude that the fermentation duration is influenced by the quality and nature of the ferment used (Flora et al., 2016).
<figure><img src="image_50.png" /></figure>

<figure><img src="image_51.png" /></figure>

<figure><img src="image_52.png" /></figure>

<figure><img src="image_53.png" /></figure>
<figure><img src="image_54.png" /><figcaption>Graph 6: Volatile Fatty Acid (VFA) content for different ferment rates</figcaption></figure>
With 2.5% *Lactobacillus fermentum* yeast for 135 hours of fermentation, the non-pre-hydrolyzed substrate based on the fruit of *Azadirachta indica* had a better ethanolic power (7.5056% v/v) than that of the non-pre-hydrolyzed substrate based on *Eichhornia crassipes* plant (7.5025% v/v).

## II-5-5-3)-Influence of the quantity of water

Following the five tests of the experiment, the samples of solutions based on the fruit of *Azadirachta indica* associated with *Eichhornia crassipes* plants (S₁, S₂ and S₃) and the control solutions (ST₁ and ST₂) show that the production of Volatile Fatty Acid (VFA) follows the same principle regardless of the quantity of water added to the different ones whose yeast rate is 2.5% with an average hydration L/S of 20.

<figure><img src="image_55.png" /><figcaption>Graph 7: Volatile Fatty Acid Content (VFA in mg/g) as a function of fermentation duration in samples from batch 1 (2.5% water +5% substrate +2.5% yeast)</figcaption></figure>
It appears from the analysis that the least hydrated sample (2.5% water) has the lowest content of VFA produced and that the production of VFA is not the highest for the sample of control solutions, whether we are in the most hydrated batch or not. On the other hand, the fermentation of media based on the fruit of *Azadirachta indica* associated with *Eichhornia crassipes* plants varies depending on the water content of the medium. This is in line with the results obtained by Flora et al., (2016) which indicates that a high or low hydration rate constitutes a limiting factor for the fermentation of *Eichhornia crassipes*.

<figure><img src="image_56.png" /><figcaption>**Graph 8:** Volatile Fatty Acid Content (VFA in mg/g) as a function of fermentation duration in samples from batch 2 (5% water + 2.5% substrate + 2.5% yeast)</figcaption></figure>

However, for samples S<sub>1</sub>, S<sub>2</sub> and S<sub>3</sub>, Volatile Fatty Acid is more produced for the first phase of fermentation, over a short period (25th hour and 55th hour), when the added
water is at 2.5%. But the production of Volatile Fatty Acid is more intense during the second phase of fermentation and extends over a relatively long period (90th hour and 136th hour) when the water content is 5%. Consequently, hydration at 5% is favorable for optimal fermentation.

## II-5-5-4)-Weight yield

The weight yield is determined. However, among the solutions based on the fruit of *Azadirachta indica* associated with *Eichhornia crassipes* plants, S₃ has the best production of bioethanol (712.19 ml/g) followed by S₂ (687.87 ml/g) then S₁ (626.37 ml/g). Their average bioethanol production obtained is 675.47 ml/g or 0.5272 g/g of *Azadirachta indica* fruit + *Eichhornia crassipes* fermented with L/S ratios between 20-25.

<table><caption>Table 7: Weight yield</caption><thead><tr><th><i>Azadirachta indica</i> fruit pulp (Milligram)</th><th><i>Eichhornia crassipes</i> plants (Milligram)</th><th>Bioethanol produced (ml/g)</th><th>Weight yield (%v/v)</th></tr></thead><tbody><tr><td>/</td><td>1000</td><td>750.25</td><td>58.56</td></tr><tr><td>1000</td><td>/</td><td>750.56</td><td>58.58</td></tr><tr><td>330</td><td>670</td><td>626.37</td><td>48.89</td></tr><tr><td>500</td><td>500</td><td>687.87</td><td>53.69</td></tr><tr><td>670</td><td>330</td><td>712.19</td><td>55.58</td></tr></tbody></table>

Concerning the control solutions, the results are similar to those found by Flora et al., (2016) which indicates that for 0.955%V/V of pure bioethanol obtained, he used 0.08 g/g of *Eichhornia crassipes* fermented with an L/S ratio of 20 while Mishima et al. (2008) found a quantity of 0.14 g of pure bioethanol for 0.1 gram of pretreated *Eichhornia crassipes*.

## CONCLUSION

The production of bioethanol based on the fruit of *Azadirachta indica* associated with *Eichhornia crassipes* plants by biochemical means consisted of pre-treatment of the fruits of *Azadirachta indica* and the *Eichhornia crassipes* plants. Pre-hydrolysis via a thermo-mechano-chemical process made it possible to destroy the lignocellulosic material and partially carry out hydrolysis. The addition of urea (NH₂CONH₂) ensured optimal yeast growth and accelerated the fermentation kinetics. Starting the second phase of fermentation by adjusting the pH with a diluted sulfuric acid solution (H₂SO₄, 1.5N) made it possible to obtain varied productions of bioethanol.

The results obtained for the fermentation of samples of the associated and pre-hydrolyzed solutions have an average level of Volatile Fatty Acid of 6.8081±0.7720mg/g while the control solutions give a better average level of Volatile Fatty Acid of 7.174±1.014 mg/g. The optimal quantities of *Lactobacillus fermentum* yeast
used for this purpose are 2.5% per dry matter of *Azadirachta indica* fruit associated with *Eichhornia crassipes* plants and a liquid to solid ratio (L/S) of 20. Furthermore, the distillation of the fermentation must makes it possible to obtain on average 675.476 ml/g of hydrated ethanol and 640.625 ml/g of CO2 with an average weight yield of 52.72±3.57%.

With a view to optimizing the results obtained, a resumption of the experiment with enzymatic pre-hydrolysis preceded by the characterization of other types of biomass often dumped and not exploited is envisaged, in order to give data useful for understanding the behavior of fermentation enzymes and bioethanol production.

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# EXERCISES AND CORRECTIONS ON THE PRODUCTION OF BIOETHANOL BASED ON EICHHORNIA CRASSIPES ASSOCIATED WITH THE PULP OF THE RIPE FRUIT OF AZADIRACHTA INDICA

Here is a series of exercises accompanied by their answers on the production of bioethanol from *Eichhornia crassipes* (water hyacinth) associated with the pulp of the ripe fruit of *Azadirachta indica* (Neem).

---

## Exercise 1: Understanding Raw Materials

**Objective:** Identify the characteristics of the raw materials used for the production of bioethanol and understand their role in the production process.

**Instructions:**

1. Describe the properties of Eichhornia crassipes and the pulp of the ripe fruit of *Azadirachta indica* that make them potential raw materials for the production of bioethanol.

2. Explain why it is advantageous to combine these two raw materials in the production process.

**Correction:**

**1. Properties of raw materials:**

- **Eichhornia crassipes:** This aquatic plant is rich in cellulose and hemicellulose, which makes it a suitable raw material for the production of bioethanol via a fermentation process after enzymatic hydrolysis.

- **Pulp of the ripe fruit of Azadirachta indica:** The pulp of this fruit contains fermentable sugars (glucose, fructose) which are easily converted into ethanol by fermentation. It is also rich in bioactive compounds, which can enrich the fermentation process.

**2. Advantages of the association:**

- **Complementarity of compositions:** *Eichhornia crassipes* provides a large quantity of biomass while the pulp of *Azadirachta indica* fruit provides the sugars necessary for efficient fermentation.

- **Process synergy:** The combination of the two raw materials can improve the ethanol yield, because *Azadirachta indica* pulp can facilitate the fermentation of compounds from the hydrolysis of *Eichhornia crassipes*.
**Resource management:** Combined use makes it possible to valorize two available and often underused sources of biomass, thus reducing the environmental impact and improving the sustainability of bioethanol production.

---

**Exercise 2: Bioethanol Production Steps**

**Objective:** Identify and understand the different stages of the bioethanol production process from *Eichhornia crassipes* and *Azadirachta indica* pulp.

**Instructions:**

1. List the main stages of the bioethanol production process from these raw materials, from harvest to final distillation.

2. For each step, explain the specific objectives and the chemical or biological reactions that take place there.

**Correction:**

**1. Main steps of the process:**

- **Harvest:** Collection of *Eichhornia crassipes* and ripe fruits of *Azadirachta indica*.

- **Preparation:** Cleaning and grinding of raw materials to increase the contact surface and facilitate the following steps.

- **Hydrolysis:** Breakdown of *Eichhornia crassipes* cellulose into simple sugars using enzymes or acids.

- **Fermentation:** Conversion of the sugars obtained (glucose, fructose) into ethanol by yeasts.

- **Distillation:** Separation of the ethanol produced from the rest of the mixture by evaporation and condensation.

- **Purification:** Elimination of impurities to obtain high quality bioethanol.

**2. Objectives and reactions:**

- **Harvest:** Ensure the availability of raw materials in sufficient quantities.

- **Preparation:** Maximize the efficiency of hydrolysis and fermentation by reducing the size of biomass particles.

- **Hydrolysis:** Convert polysaccharides (cellulose, hemicellulose) into fermentable monosaccharides (example: $C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO_2$ during fermentation).

- **Fermentation:** Yeasts transform sugars into ethanol and carbon dioxide.
- **Distillation:** Separating ethanol from water and other compounds present to obtain a higher concentration of ethanol.

- **Purification:** Improve the purity of bioethanol for specific applications (fuel, solvents, etc.).

---

## Exercise 3: Process Yield and Effectiveness

**Objective:** Analyze the factors that influence bioethanol yield and evaluate the efficiency of the production process.

**Instructions:**

1. Imagine that you obtained the following data after an experimental production of bioethanol: 100 kg of *Eichhornia crassipes* and 20 kg of *Azadirachta indica* pulp were used. The process produced 15 liters of bioethanol. Calculate the bioethanol yield (in liters per kilogram of biomass).

2. Discuss the factors that could influence this performance, and suggest strategies to improve it.

**Correction:**

1. **Calculation of yield:**

- Total biomass used = 100 kg + 20 kg = 120 kg

- Bioethanol yield = 15 liters / 120 kg = 0.125 liters/kg

2. **Factors influencing performance:**

- **Quality of raw materials:** The cellulose content of *Eichhornia crassipes* and sugar content of *Azadirachta indica* pulp may vary, affecting the ethanol yield.

- **Hydrolysis efficiency:** Incomplete hydrolysis could leave some of the polysaccharides unconverted into fermentable sugars.

- **Fermentation conditions:** Temperature, pH, and yeast strain used can have a significant impact on the conversion of sugars to ethanol.

- **Loss during distillation:** Losses of ethanol can occur during distillation if it is not optimized.

**Strategies to improve performance:**

- **Optimization of hydrolysis:** Use specific enzymes and adjust conditions to maximize the conversion of polysaccharides to sugars.
**- Improvement of fermentation conditions:** Use resistant yeasts and optimize culture conditions to increase ethanol yield.

**-Loss reduction:** Optimize the distillation process to minimize ethanol losses and increase the purity of the final product.

---

**Exercise 4: Environmental and Economic Impact**

**Objective:** Evaluate the environmental and economic impact of bioethanol production from *Eichhornia crassipes* and *Azadirachta indica* pulp.

**Instructions:**

1. Identify the environmental benefits of producing bioethanol from these feedstocks compared to fossil fuels.

2. Analyze the potential costs linked to the production of bioethanol from these biomasses, taking into account economic and logistical aspects.

3. Propose recommendations to maximize environmental benefits and minimize production costs.

**Correction:**

**1. Environmental benefits:**

**- Reduction of CO2 emissions:** Bioethanol is a renewable energy that can replace fossil fuels, thus reducing greenhouse gas emissions.

**- Use of waste:** The transformation of water hyacinth, often considered an invasive plant, into bioethanol makes it possible to valorize an underused resource, while contributing to the management of aquatic ecosystems.

**- Preservation of fossil resources:** By replacing part of fossil fuels, bioethanol contributes to reducing dependence on non-renewable energies.

**2. Cost analysis:**

**- Collection and transport costs:** Harvesting and transporting *Eichhornia crassipes* and *Azadirachta indica* fruits can be expensive, especially if production sites are remote.

**- Processing costs:** The preparation, hydrolysis, fermentation, and distillation stages require equipment and energy, which can increase production costs.

**- Cost of enzymes:** Enzymatic hydrolysis can be expensive, especially if the enzymes must be imported or if their local production is limited.

**3. Recommendations:**
- **Optimization of supply chains:** Develop efficient collection and transport strategies to reduce transport costs
# PARTIE 3: EDUCATION ENVIRONNEMERSEPTION DES CHANGEMENTS CLIMATIQUES

<figure><img src="image_57.png" /></figure>
Environmental education plays a crucial role in how climate change is perceived and how individuals and communities respond to these challenges. Here's how environmental education influences perceptions of climate change and how it can be optimized to improve awareness and response to climate issues:

# 1. Impact of Environmental Education on the Perception of Climate Change

## a. Increased Awareness

**-Knowledge of Causes and Consequences:** Environmental education informs individuals about the causes of climate change (such as greenhouse gas emissions) and its potential consequences (such as extreme weather events and sea level rise).

**-Sign Recognition:** By learning to identify the signs of local and global climate change, individuals become more aware of the impacts on their immediate environment.

## b. Change of Attitudes

**-Ecological Awareness:** A better understanding of climate issues often leads to increased awareness of individual and collective responsibilities for environmental protection.

**-Behavior Changes:** Education can influence behavior by encouraging sustainable practices such as reducing carbon emissions, energy conservation and recycling.

## c. Influence on Policies and Community Initiatives

**-Engagement in Initiatives:** A better understanding of climate change can encourage individuals to participate in local emissions reduction or climate resilience initiatives.

**-Advocacy and Pleasure:** People educated on climate issues are more likely to defend public policies favorable to sustainability and adaptation to climate change.

# 2. Approaches to Optimizing Environmental Education on Climate Change

## a. Integration into School Curricula

**-Educational Programs:** Incorporate climate change into school curricula at all levels to ensure that younger generations understand the issues from an early age.

**-Practical Activities:** Use hands-on projects, field experiments, and simulations to help students understand the real impacts of climate change.

## b. Training of Educators

**-Professional Development:** Train teachers and trainers on topics related to climate change so that they can transmit accurate and current information.
**-Educational Resources:** Provide educators with educational resources and tools to effectively teach climate change and its impacts.

**c. Public Awareness Campaigns**

**-Media and Communication:** Use the media, including social networks, television, and radio, to disseminate messages on climate change and promote concrete actions.

**-Community Events:** Organize events such as forums, workshops, and exhibitions to discuss the impacts of climate change and possible solutions.

**d. Partnerships and Collaboration**

**-Collaboration with NGOs:** Work with non-governmental organizations to create educational programs and resources on climate change.

**-Partnerships with the Private Sector:** Engage companies in awareness-raising and training initiatives on reducing carbon footprints and sustainable practices.

**e. Awareness and Community Engagement Programs**

**-Local Initiatives:** Encourage communities to develop their own educational initiatives on climate change, adapted to their local contexts.

**-Participatory Projects:** Involve community members in environmental management and climate risk reduction projects to increase their engagement and understanding of the issues.

**f. Use of Technologies and Innovations**

**-Applications and Digital Tools:** Develop applications and digital tools to educate people about climate change and encourage them to adopt sustainable practices.

**-Interactive Resources:** Create interactive simulations and educational games to help individuals visualize the impacts of climate change and understand possible solutions.

**3. Evaluation of the Effectiveness of Environmental Education**

**-Measurement of Changes in Knowledge:** Regularly assess the levels of knowledge and understanding of climate change among participants in educational programs.

**-Behavior Assessment:** Track changes in behavior and actions taken by individuals in response to environmental education on climate change.

**4. Examples of Good Practices**
**-Youth Programs:** Initiatives like the “Youth Climate Action” program which educates young people about climate change and engages them in awareness projects.

**-Online Climate Education:** Free online courses like those offered by universities and educational platforms that provide information on climate change and solutions.

In summary, environmental education is essential to improve perceptions of climate change and to motivate individuals and communities to adopt more sustainable behaviors. By integrating climate change into curricula, training educators, and conducting awareness campaigns, it is possible to strengthen understanding of climate issues and promote positive actions to mitigate the impacts of climate change.
# CHAPTER 1. ENVIRONMENTAL EDUCATION:
## COMPARATIVE STUDY OF THE PERFORMANCE OF TWO
## TRAINING METHODS IN SAHELIAN FARMING
## ENVIRONMENTS

Alexis DZOKOM<fnref n="1" />, Jules BALNA<fnref n="2" />, Félix WATANG ZIEBA<fnref n="2" />, Roger DJOULDE DARMAN<fnref n="3" />

## ABSTRACT

The acceptance of messages related to the preservation and conservation of the environment within populations depends in part on the training methods used in the Sahel zone. The objective in this article is to measure the achievement of the training goals via educational and andragogical methods by analyzing the perception that the participants have of their training achievements. 300 trainers in plant resource management education in the Sahel region were invited to the survey carried out using a questionnaire and training session evaluation sheets. Data analysis made it possible to determine that 97.57% of the trained people surveyed were satisfied and 95.87% could reproduce the knowledge related to good environmental practices. The practical method of andragogy made it possible to transmit knowledge better than the practical method of pedagogy

**Keywords:** Environmental education, training, learning, management of plant resources, Sahelian zones

## INTRODUCTION

Despite sporadic initiatives, a certain dissonance is currently perceptible between the interests of target populations, the possible positive environmental and socio-economic impacts arising from environmental education and the acceptance of certain types of training in preservation and conservation. of the environment within the populations of current Sahelian zones. Environmental pedagogy, used during training in good environmental practices, must provide learners with a certain knowledge, at the same time as it is responsible for encouraging them to acquire a set of attitudes and habits supported and enlivened by a few specific skills (Giolitto, 1982). Environmental pedagogy can only be judged effective if it is based on appropriate teacher training, if it opens up to the extra-curricular environment, if it is

<footnote n="1">¹Department of Environmental Sciences, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>

<footnote n="2">²Department of Geography, Faculty of Arts Letters and Social Sciences, University of Maroua, Cameroon</footnote>

<footnote n="3">³Department of Agriculture Animal Husbandry and By-Products, National Advanced School of Engineering, University of Maroua, Cameroon</footnote>
based on ongoing educational research likely to shed light on its purposes and methods (Giolitto, 1993).

"Andragogy is part of Educational Sciences. But the concept is much less used than that of pedagogy and the term pedagogical which is easily found in speeches on andragogy. » (Akouéte, 2021, p 25).

Environmental education can take different forms; formal, non-formal and informal (Ayotte, 2020).

"Induced in particular by this contact with nature, the development of a passion, or at least of a motivation towards the protection of the environment is also of great importance in the process" (R. Dallaire, 2023, p 4).

Adults, young and old, are increasingly interested in activities that offer environmental learning (Villemagne and Sauvé, 2021). For the development of children, interaction with their environment is essential to establish their relationship with the world and promote their understanding of it.

The objective of this article is to measure the achievement of the training goals and to analyze the perception of the participants after the training acquired in order to propose a better methodological program for training sessions on good environmental practices in the Sahelian zone. More specifically, it is a question of determining the levels of achievement of the objectives of environmental education via andragogical methods on the one hand and the levels of achievement of the objectives of environmental education via pedagogical methods on the other hand. The comparison of these two types of methodological approaches makes it possible to determine a typology of approach to adopt during training in good environmental practices.

# 1- MATERIALS AND METHOD

## 1-1 Study sites

The study sites were identified in the Far North and North Cameroon regions, Sahelian zone, in ten localities. These are the localities of Mokolo, Maroua, Mora, Garoua, Guider (for the Sahelian semi-arid zone) and Waza, Makari, Lagdo, Yagoua and Maga (for the Sahelian humid zone). These localities were chosen because they are part of the humid zone and/or the Sahelian semi-arid zone:
<figure><img src="image_58.png" /><figcaption>Figure 1: Coordinates of the chosen localities</figcaption></figure>

Three localities in the Northern region were chosen for the study while the other seven localities belong to the Far North region.

**1-1 Data collection method**

The Active Method of Research and Participation Planning (MARPP) used as part of this work consisted of more or less structured interviews (Dzokom, 2021). This socio-economic data collection tool aims to obtain information in person, individually or in small groups, through a series of questions asked (Dzokom, 2021). The information collected is recorded in a sheet serving as a conversation guide with the possibility of readjusting the questions during the interview. This data collection method was mainly carried out before, during and after the training sessions, with a view to determining the perception of people trained in good environmental practices in the Sahel region.

In total, 300 people trained in education in the management of plant resources in the Sahelian zones including: 100 investigators, 100 resource conservationists and 100 producers of bioenergy resources who all agreed to participate in the survey, i.e. 30±02 people trained by locality. The people surveyed were chosen randomly from the directory of workers trained within the Non-Governmental Organization SAHEL NATURE CONSULTING FOR COMMUNITY between 2021-2023. Overall, the questionnaire used included 9 sections:

* Identification of the person trained: name, gender, age, level of education and experience in the professional environment;
* The targets of the trained person;

* The description of the training activity carried out linked to the person trained: targets, production levels, optimal production periods, means of production;

* The means for implementing the training acquired: availability, capacity, type of energy used, cost, area covered by the activity, method of improving the means used;

* The professional productivity system adopted;

* The perception of the training acquired;

* The levels of returns on training acquired.

## 1-2- Data analysis

The raw data are collected from each questionnaire, entered and formatted with Microsoft Office Excel software and imported in the form of text files (separator: tabulation) into R and SPSS software for subsequent statistical analyses, namely: analysis descriptive and the correlation test. The descriptive analysis consisted of calculations of proportions (percentages), means and standard deviations. Graphs and tables were constructed. The sperman correlation test made it possible to make a typology of the training methods investigated on the basis of the types of perception of the people trained. Given that the study sample was made up equally of men and women, the variables "age" and "level of education" linked to the people trained were also retained for this typology:

- The "age" variable has three modalities: the "Young" (YOUNG) modality for trained people whose age is < 45 years old, the "Aged" (AG) modality for trained people whose age is between 45 years and 60 years and the "Very elderly" (TAG) modality for trained people whose age is > 60 years;

- The variable "education level" has three modalities: "trained person without formal level of education" (ANALF), trained people who have reached the primary level of formal education (PRIM) and trained people who have reached the secondary level (SEC) and more.

## 2- RESULTS

### 2-1 Characteristics of the trained people surveyed

The trained people surveyed consist of 179 people displaced for various reasons and 121 host people (indigenous). They were distributed as follows:
<table><caption>Table 1: Distribution of trained people surveyed</caption><thead><tr><th rowspan="2">Sites</th><th colspan="2">Host people (indigenous)</th><th colspan="2">People displaced by insecurity</th><th colspan="2">Environmentally displaced people</th><th colspan="2">People displaced for other reasons</th><th colspan="2">Total</th></tr><tr><th>H</th><th>F</th><th>H</th><th>F</th><th>H</th><th>F</th><th>H</th><th>F</th><th>H</th><th>F</th></tr></thead><tbody><tr><td>Waza</td><td>10</td><td>09</td><td>02</td><td>04</td><td>01</td><td>02</td><td>02</td><td>-</td><td>15</td><td>15</td></tr><tr><td>Makari</td><td>13</td><td>06</td><td>02</td><td>03</td><td>01</td><td>03</td><td>01</td><td>01</td><td>17</td><td>13</td></tr><tr><td>Lagdo</td><td>15</td><td>07</td><td>01</td><td>02</td><td>02</td><td>02</td><td>-</td><td>01</td><td>18</td><td>12</td></tr><tr><td>Yagoua</td><td>08</td><td>09</td><td>04</td><td>04</td><td>01</td><td>02</td><td>02</td><td>-</td><td>15</td><td>15</td></tr><tr><td>Maga</td><td>14</td><td>09</td><td>03</td><td>03</td><td>-</td><td>01</td><td>-</td><td>-</td><td>17</td><td>13</td></tr><tr><td>Mokolo</td><td>12</td><td>09</td><td>04</td><td>04</td><td>-</td><td>01</td><td>-</td><td>-</td><td>16</td><td>14</td></tr><tr><td>Maroua</td><td>11</td><td>09</td><td>02</td><td>04</td><td>01</td><td>01</td><td>01</td><td>01</td><td>15</td><td>15</td></tr><tr><td>Mora</td><td>09</td><td>09</td><td>02</td><td>04</td><td>01</td><td>02</td><td>03</td><td>-</td><td>15</td><td>15</td></tr><tr><td>Garoua</td><td>10</td><td>09</td><td>03</td><td>01</td><td>04</td><td>01</td><td>02</td><td>-</td><td>19</td><td>11</td></tr><tr><td>Guider</td><td>12</td><td>11</td><td>02</td><td>01</td><td>01</td><td>01</td><td>-</td><td>02</td><td>15</td><td>15</td></tr></tbody></table>

During our study, the sample of trained people surveyed is made up of host populations (67%), people displaced due to insecurity (18.33%), people displaced due to the degraded environment (9.33%) and people displaced for other reasons (5.33%). The variables linked to the trained people surveyed are essentially of six orders. These are the variables sex, age, level of education and the number of years of experience in environmental activities which were recorded in Table 1.

<table><caption>Table 2: Characteristics of the trained people surveyed: gender, average age, level of education and number of years of professional experience</caption><thead><tr><th rowspan="2">Sites</th><th colspan="2">Sexe</th><th rowspan="2">Average age</th><th colspan="3">Educational level (%)</th><th rowspan="2">Number of years of professional experience</th></tr><tr><th>M</th><th>F</th><th>Level of Preschool Instruction</th><th>Primary Education Level</th><th>Secondary Education Level</th></tr></thead><tbody><tr><td>Waza</td><td>15</td><td>15</td><td>41.37±2.94</td><td>71.71±2.30</td><td>16.54±1.72</td><td>11.11±0.85</td><td>03.54±0.11</td></tr><tr><td>Makari</td><td>17</td><td>13</td><td>40.51±1.31</td><td>73.39±1.38</td><td>15.05±3.32</td><td>11.75±0.26</td><td>01.53±0.93</td></tr><tr><td>Lagdo</td><td>18</td><td>12</td><td>41.32±5.12</td><td>70.99±3.32</td><td>17.06±0.91</td><td>11.56±0.37</td><td>02.12±0.22</td></tr><tr><td>Yagoua</td><td>15</td><td>15</td><td>46.51±6.41</td><td>72.47±1.08</td><td>15.60±2.84</td><td>11.95±0.28</td><td>02.39±0.84</td></tr><tr><td>Maga</td><td>17</td><td>13</td><td>45.28±5.74</td><td>71.51±1.43</td><td>17.38±1.61</td><td>12.48±0.93</td><td>02.51±0.28</td></tr><tr><td>Mokolo</td><td>16</td><td>14</td><td>41.05±4.47</td><td>71.93±0.27</td><td>17.59±2.34</td><td>11.93±2.94</td><td>01.53±0.48</td></tr><tr><td>Maroua</td><td>15</td><td>15</td><td>45.12±3.43</td><td>70.11±2.31</td><td>18.58±1.87</td><td>11.02±0.19</td><td>01.17±0.29</td></tr><tr><td>Mora</td><td>15</td><td>15</td><td>40.11±5.09</td><td>70.72±1.73</td><td>18.57±1.02</td><td>10.91±0.20</td><td>02.32±0.83</td></tr><tr><td>Garoua</td><td>19</td><td>11</td><td>41.28±3.51</td><td>71.39±1.23</td><td>20.06±1.05</td><td>11.32±0.92</td><td>03.54±0.49</td></tr><tr><td>Guider</td><td>15</td><td>15</td><td>42.34±2.73</td><td>70.51±2.12</td><td>15.59±0.32</td><td>9.22±0.22</td><td>01.11±0.72</td></tr></tbody></table>

The distribution of the trained people surveyed in the study sample by gender shows that these trained people surveyed are made up of men (M) at 16.2±1.47 and women (F) at 13.8±1.47. Their average age is 42.49±2.28 years. The majority of trained people surveyed have a level of pre-school education, i.e. 71.47±0.97%, those with a level of primary education are at 17.20±1.57% while we observe that those with a secondary
education level at 11.32±0.89%. The trained people surveyed have on average 02.17±0.87 years of experience in environmental activities.

## 2-2 Training objectives via the theoretical andragogy method

During training sessions using the theoretical andragogy method, the participation rate of people displaced by the environment or for other reasons, who were trained and surveyed, is 100% among both men and women. The average participation rate of people displaced due to insecurity is 92±25.29% among women and 91±28.46% among men. People from the host population were poorly participatory with an average participation rate of 85.8±11.49% among women and 36.6±28.96% among men.

<table><caption>Table 4: Average participation rate for theoretical training sessions with the andragogy method</caption><thead><tr><th rowspan="2">Sites</th><th colspan="2">Host people (%)</th><th colspan="2">People displaced due to insecurity (%)</th><th colspan="2">Environmentally displaced people (%)</th><th colspan="2">People displaced for other reasons (%)</th></tr><tr><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th></tr></thead><tbody><tr><td>Waza</td><td>10</td><td>90</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Makari</td><td>31</td><td>60</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Lagdo</td><td>51</td><td>70</td><td>10</td><td>20</td><td>100</td><td>100</td><td>-</td><td>100</td></tr><tr><td>Yagoua</td><td>80</td><td>90</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Maga</td><td>41</td><td>90</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Mokolo</td><td>21</td><td>90</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Maroua</td><td>11</td><td>90</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Mora</td><td>90</td><td>90</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Garoua</td><td>10</td><td>90</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Guider</td><td>21</td><td>98</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td><td>100</td></tr></tbody></table>

Table 5 describes the level of satisfaction expressed by the trained people surveyed for the modules taught via the theoretical andragogy method.

<table><caption>Table 5: Level of satisfaction of those trained with the progress of the different theoretical training modules via the andragogy method</caption><thead><tr><th>Level of satisfaction with the different training modules carried out</th><th>Completely satisfied (%)</th><th>Partly satisfied (%)</th><th>Insufficiently satisfied (%)</th><th>Not at all satisfied (%)</th></tr></thead><tbody><tr><td>Module 1: Training in bioenergy production (ecological coal and biogas)</td><td>16.06</td><td>10.00</td><td>57</td><td>12</td></tr><tr><td>Module 2: Training in organic fertilizer production</td><td>09.85</td><td>01.09</td><td>43</td><td>41</td></tr><tr><td>Module 3: Training in plant production and intelligent reforestation</td><td>09.78</td><td>04.07</td><td>41</td><td>41</td></tr><tr><td>Module 4: Training in the restoration of eroded soils</td><td>9.83</td><td>08.03</td><td>22</td><td>54</td></tr></tbody></table>
The level of satisfaction of the people trained with the progress of the different theoretical training modules via the andragogy method reveals that the people surveyed are mainly Insufficiently satisfied (40.75±14.38%) and not at all satisfied acquired knowledge (37±17.76%). Those who were completely satisfied (11.38±3.12%) and partly satisfied (5.79±3.99%) are poorly represented.

## 2-3 Training objectives via the practical andragogy method

During training sessions using the practical andragogy method, the participation rate of people displaced by the environment or for other reasons, who were trained and surveyed, is 100% among both men and women. The average participation rate of people displaced due to insecurity is 98.7±4.11% among women and 97±9.48% among men. People from the host population were poorly participatory with an average participation rate of 99.5±0.85% among women and 96.2±2.94% among men.

<table><caption>Table 6: Average participation rate for practical training sessions with the andragogy method</caption><thead><tr><th rowspan="2">Sites</th><th colspan="2">Host people (%)</th><th colspan="2">People displaced due to insecurity (%)</th><th colspan="2">Environmental displaced people (%)</th><th colspan="2">People displaced for other reasons (%)</th></tr><tr><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th></tr></thead><tbody><tr><td>Waza</td><td>90</td><td>99</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Makari</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Lagdo</td><td>94</td><td>100</td><td>70</td><td>87</td><td>100</td><td>100</td><td>-</td><td>100</td></tr><tr><td>Yagoua</td><td>98</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Maga</td><td>96</td><td>98</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Mokolo</td><td>98</td><td>100</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Maroua</td><td>97</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Mora</td><td>96</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Garoua</td><td>99</td><td>98</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Guider</td><td>94</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td><td>100</td></tr></tbody></table>

Table 7 describes the level of satisfaction expressed by the trained people surveyed for the modules taught via the practical andragogy method.

<table><caption>Table 7: Level of satisfaction of people trained during the different practical training modules via the andragogy method</caption><thead><tr><th>Level of satisfaction with the different training modules carried out</th><th>Completely satisfied (%)</th><th>Partly satisfied (%)</th><th>Insufficiently satisfied (%)</th><th>Not at all satisfied (%)</th></tr></thead><tbody><tr><td>Module 1: Training in bioenergy production (ecological coal and biogas)</td><td>100</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Module 2: Training in organic fertilizer production</td><td>98.05</td><td>01.93</td><td>-</td><td>-</td></tr><tr><td>Module 3: Training in plant production and intelligent reforestation</td><td>99.07</td><td>00.81</td><td>-</td><td>-</td></tr></tbody></table>
<table><tr><td>Module 4: Training in the restoration of eroded soils</td><td>100</td><td>-</td><td>-</td><td>-</td></tr></table>

The level of satisfaction of the people trained with the progress of the various practical training modules via the andragogy method reveals that the people surveyed are mostly completely satisfied (99.28±0.93%) and very few are in part satisfied with the knowledge acquired (0.81%).

## 2-4 Training objectives via the theoretical teaching method

During training sessions for young people whose ages vary between [7-30] years, via the theoretical pedagogy method, the participation rate of people displaced due to the environment or for other reasons, who have been trained and surveyed is 100% among both young men and young women. The average participation rate of people displaced by insecurity is 97.6±7.58% among women and 98.9±3.48% among men. People from the host population were poorly participatory with an average participation rate of 75.7±4.08% among women and 36.6±4.20% among men.

<table><caption>Table 8: Average participation rate for theoretical training sessions with the teaching method</caption><thead><tr><th rowspan="2">Sites</th><th colspan="2">Host people (%)</th><th colspan="2">People displaced due to insecurity (%)</th><th colspan="2">Environmental displaced people (%)</th><th colspan="2">People displaced for other reasons (%)</th></tr><tr><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th></tr></thead><tbody><tr><td>Waza</td><td>57</td><td>76</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Makari</td><td>54</td><td>74</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Lagdo</td><td>65</td><td>72</td><td>89</td><td>76</td><td>100</td><td>100</td><td>-</td><td>100</td></tr><tr><td>Yagoua</td><td>59</td><td>78</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Maga</td><td>49</td><td>73</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Mokolo</td><td>53</td><td>75</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Maroua</td><td>55</td><td>86</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Mora</td><td>54</td><td>75</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Garoua</td><td>56</td><td>72</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Guider</td><td>57</td><td>76</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td><td>100</td></tr></tbody></table>

Table 9 describes the level of satisfaction expressed by the trained people surveyed for the modules taught via the theoretical teaching method.
<table><caption>Table 9: Level of satisfaction of those trained with the progress of the different theoretical training modules via the teaching method</caption><thead><tr><th>Level of satisfaction with the different training modules carried out</th><th>Completely satisfied (%)</th><th>Partly satisfied (%)</th><th>Insufficiently satisfied (%)</th><th>Not at all satisfied (%)</th></tr></thead><tbody><tr><td>Module 1: Training in bioenergy production (ecological coal and biogas)</td><td>34.55</td><td>09.57</td><td>55.65</td><td>12</td></tr><tr><td>Module 2: Training in organic fertilizer production</td><td>43.43</td><td>07.78</td><td>38.43</td><td>10.36</td></tr><tr><td>Module 3: Training in plant production and intelligent reforestation</td><td>36.58</td><td>04.67</td><td>41.98</td><td>16.77</td></tr><tr><td>Module 4: Training in the restoration of eroded soils</td><td>45.38</td><td>06.45</td><td>22.78</td><td>25.39</td></tr></tbody></table>

The level of satisfaction of the people trained with the progress of the different theoretical training modules via the teaching method reveals that the majority of the people surveyed are completely satisfied (39.98±5.23%) and insufficiently satisfied (39.71±13.51%). Those who were not at all satisfied with the knowledge acquired (16.13±6.74%) and partly satisfied (7.11±2.07%) are low.

## 2-5 Training objectives via the practical teaching method

During training sessions using the practical teaching method, the participation rate of people displaced by the environment or for other reasons, who were trained and surveyed, is 100% for both men and women. The average participation rate of people displaced due to insecurity is 98.7±4.11% among women and 97±9.48% among men. People from the host population were poorly participatory with an average participation rate of 99.6±0.51% among women and 98.5±0.97% among men.

<table><caption>Table 6: Average participation rate for practical training sessions with the teaching method</caption><thead><tr><th rowspan="2">Sites</th><th colspan="2">Host people (%)</th><th colspan="2">People displaced due to insecurity (%)</th><th colspan="2">Environmental displaced people (%)</th><th colspan="2">People displaced for other reasons (%)</th></tr><tr><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th><th>M</th><th>F</th></tr></thead><tbody><tr><td>Waza</td><td>97</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Makari</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Lagdo</td><td>98</td><td>100</td><td>70</td><td>87</td><td>100</td><td>100</td><td>-</td><td>100</td></tr><tr><td>Yagoua</td><td>99</td><td>99</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Maga</td><td>98</td><td>99</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Mokolo</td><td>99</td><td>100</td><td>100</td><td>100</td><td>-</td><td>100</td><td>-</td><td>-</td></tr><tr><td>Maroua</td><td>98</td><td>99</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td></tr><tr><td>Mora</td><td>98</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Garoua</td><td>100</td><td>99</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td></tr><tr><td>Guider</td><td>98</td><td>100</td><td>100</td><td>100</td><td>100</td><td>100</td><td>-</td><td>100</td></tr></tbody></table>

Table 7 describes the level of satisfaction expressed by the trained people surveyed for the modules taught via the practical teaching method
<table><caption>Table 7: Level of satisfaction of people trained during the different practical training modules via the teaching method</caption><thead><tr><th>Level of satisfaction with the different training modules carried out</th><th>Completely satisfied (%)</th><th>Partly satisfied (%)</th><th>Insufficiently satisfied (%)</th><th>Not at all satisfied (%)</th></tr></thead><tbody><tr><td>Module 1: Training in bioenergy production (ecological coal and biogas)</td><td>94.67</td><td>-</td><td>04.54</td><td>0.79</td></tr><tr><td>Module 2: Training in organic fertilizer production</td><td>98.05</td><td>01,93</td><td>-</td><td>0.02</td></tr><tr><td>Module 3: Training in plant production and intelligent reforestation</td><td>99.07</td><td>0.81</td><td>-</td><td>0.12</td></tr><tr><td>Module 4: Training in the restoration of eroded soils</td><td>92.26</td><td>6.93</td><td>0.81</td><td>-</td></tr></tbody></table>

The level of satisfaction of the people trained with the progress of the various practical training modules via the teaching method reveals that the people surveyed are mostly completely satisfied (96.01±3.13%), very few are insufficiently satisfied (e) (2.81%) and partly satisfied (02.14±1.88%) with the knowledge acquired. However, 00.84±0.09% of those trained are not at all satisfied.

## 3- Analysis

### 3-1 Average participation rate in training sessions

During training sessions using the andragogy method, the participation rate during the practical and theoretical sessions, of people displaced due to the environment or for other reasons, who were trained and surveyed is 100% as long as in men than in women (Graph 1).

The average participation rate during practical sessions using the andragogy method for people displaced due to insecurity is 98.7±4.11% among women and 97±9.48% among men while the average participation rate during theoretical sessions using the andragogy method for people displaced due to insecurity is 92±25.29% among women and 91±28.46% among men (Graph 1).
<figure><img src="image_59.png" /><figcaption>Graph 1: Average participation rate in theoretical and practical training sessions with the andragogy method</figcaption></figure>

People from the host population were poorly participatory during the practical sessions via the andragogy method with an average participation rate of 99.5±0.85% among women and 96.2±2.94% among men while people from the host population were weakly participatory during the theoretical sessions via the andragogy method with an average participation rate of 85.8±11.49% among women and 36.6±28.96% among men (Graph 1).

During training sessions for young people whose ages vary between [7-30] years, via the method of theoretical and practical pedagogy, the participation rate of people displaced due to the environment or for other reasons, who have been trained and surveyed is 100% among both young men and young women (Graph 2).

The average participation rate during practical sessions using the pedagogy method for people displaced due to insecurity is 97.6±7.58% among women and 98.9±3.48% among men while the average participation rate during theoretical sessions using the
pedagogy method for people displaced due to insecurity is 98.7±4.11% among women and 97±9.48% among men (Graph 2).

<figure><img src="image_60.png" /><figcaption>Graph 2: Average participation rate in theoretical and practical training sessions with the teaching method</figcaption></figure>

People from the host population were poorly participatory during the practical sessions via the teaching method with an average participation rate of 75.7±4.08% among women and 36.6±4.20% among men while that people from the host population were poorly participatory on average during the theoretical sessions via the teaching method with an average participation rate of 99.6±0.51% among women and 98.5±0.97% among men (Graph 2).

From the first analysis, it appears that the participation rates during the practical phases were much better than during the theoretical phases (Graph 3).

The comparison of the practical phases makes it possible to determine that the participation rate during the practical training sessions via andragogy and pedagogy methods, people displaced due to the environment or for other reasons were present at 100% as long as in men than in women.