沙漠研究 22-1, 99 -102 (2012 )"ICAL 1 / DT X"

Journal of Arid Land Studies－Refereed Paper－Effect Estimation of Dry-Toilet Application for Rural Farmer Family
in Burkina Faso
Ken USHIJIMA*1), Nowaki HIJIKATA1), Ryusei ITO1) and Naoyuki FUNAMIZU1)
Abstract: Water, sanitation and agriculture are important issues in Burkina Faso. In arid areas where water is significantly
important resources, a dry-toilet-based resource recycling sanitation system seems more suitable than a conventional
water-flush-toilet-based sanitation system. For designing that kind of sanitation system, the important factor is not only the treatment
technology but also the material flow design of the total system. As a first step for designing the optimal material flow, this study
carried out a household survey in the rural area of Burkina Faso, to reveal the current condition of water related material flow in andaround a household. According to the results, the effect of the resource recycling sanitation system application was estimated asfollows. Urine can replace almost half of chemical fertilizer. Graywater reuse allows this household to expand only 17 to 37 m2 ofvegetable garden however, it can irrigate through a year to the adjacent vegetable garden. This may enable a different schedule ofcultivation to what is generally practiced with the farmer cultivating and selling produce strategically.
Key Words: Composting toilet, Urine reuse, Water reuse

1. Introduction
Burkina Faso, located in the Sub-Sahara, belongs to thesemiarid area and the main soil type are Lixisols (FAO, 1991).
It is possible to undertake agriculture but conditions are severe.
A system that provides efficient usage of water and fertilizer isdesired. On the other hand, the proportion of population
using an improved sanitation facility was only 11% in 2008
(UN, 2010). The under-five mortality rate is 11th highest in
the world; 169 per 1000 live birth and diarrhea occupies 19%
of causes of these deaths (WHO, 2010). Water and sanitation
are clearly urgent issues in Burkina Faso.
Direct disposal of human excreta or graywater causes
deterioration of sanitary condition, though they have highpotential as fertilizer or irrigation water. Water, sanitation andagriculture issues are closely related to each other in the living
environment therefore the solution should be discussed thoseissues comprehensively.
Some of authors are proposing a comprehensive concept ofsanitation system which recycles human excreta andwastewater with dry-toilet, which does not use flush water or
expensive infrastructure, and has a simple graywater treatment
facility such as slanted soil system (Fig. 1, Lopez et al., 2002).
The main target is rural areas because only small increases in
distribution of improved sanitation are observed there. It is
however not easy to make rural people invest in sanitation
system because of their low income. Especially for sanitation,
the expected results of improved sanitation are improvement ofpublic health however it takes time until general citizens canrecognize the benefit of that improvement. Some other clear
incentive is necessary.
One possibility is obtaining an income increase through a
resource recycling system. In our concept, wastewater andexcreta will have new values as irrigation water and fertilizer,
and this will provide another value as agricultural products
following cultivation. If farmers could sell the products andincrease their income, it will be a great incentive for adoption.
To create an incentive as mentioned above, the current
condition of water and material flows in a rural household
including agricultural activity should be analyzed first. In thisstudy, firstly water and material flow is described through adetailed interview survey on one rural household. Additional
information about agricultural activity for vegetable cultivation
is described following a field interview. The effect ofapplication of the resource recycling sanitation system isevaluated.

* Corresponding Author: uken@eng.hokudai.ac.jp
Kita13, Nishi8, Kita-ku, Sapporo, Hokkaido, 060-8628, Japan1) Laboratory on Engineering for Sustainable Sanitation, Faculty of Engineering, Hokkaido University, Japan.

Fig. 1. Location of field.

Fig. 2. Location of field.
Fig.3. Outside view of Mr. OP’s resident.

2. Materials and Methods
2.1. Material flow survey
Field investigations were undertaken in the rural area ofZiniaré commune (Fig. 2) which is located about 35 km fromthe capital Ouagadougou. An interview survey was held for
one agricultural household in Kologondiessé village on 12thand 17th September 2010. This household was chosenrandomly from 20 households, those the village chief chose
and allowed us to undertake an interview survey.
The content of the interview concerns water source, usage
and discharge, agricultural activities and so on. The purpose ofthis research is to reveal whole material flow, therefore anondirective interview was applied. To avoid misunderstanding,visual observation in the site was combined with interview.
2.2. Agricultural activity survey
An additional interview survey was held in four vegetablegardens in Ouagadougou on 24th and 30th March 2011. As
indicated by Kedwide et al. (2009), many vegetable gardens
are located along reservoirs. Three of four study sites arelocated along the Numèro Reservoir and one is located along asmall reservoir (name unknown). Interview to farmers about
their vegetable cultivation activity including selling activity
was carried out.

3. Results and Discussion
3.1. Material flow survey
3.1.1. Overview of the household
The household consisted of 18 person including 3 babies.
Figure 3 shows outside view of their house. The interviewee
was an adult male person. In this article, the pseudonym “Mr.
OP” is used. The main income source of this household wasselling vegetable and livestock and most of their food wassupplied from their own farmland.
3.1.2. Water use
Water for use in the walled house area, called concession,
was carried from a well with manual pump, which is about 150
m from the house. Water was carried in a 20 L plastic tank,Fig.4. Water storage crock.

and stored in ceramic crocks with a capacity of about 100 L(Fig. 4). This water was used for drinking, cooking, dishwashing and bathing. The total amount of water use in a dayby this household was 100 to 200 L. Therefore per capita use
is estimated as 7 to 14 L/day; here we ignored the three babies
as water consumers. This is smaller than reported amount indeveloping countries (FAO, 2010). One shallow well existed
about 50 m from the house. Mr. OP’s family used this water
only for washing cloth, livestock and small vegetable garden.
This shallow well dries up in the dry season, therefore, they
have to go to the reservoir, about 4 km from the house, andwash clothes and give water to livestock there.
All wastewater generated in the concession was disposedto the ground directly. Because the ground in the concession
was beard soil, disposed wastewater can be absorbed and dried
easily. Possible materials contained in the graywater fromthis family were organic material from food residues anddetergent for dish washing and bathing. Regarding organic
material, most came from self produced crops and vegetables.
The only thing they bought from market was seasoning such as
salts and cooking oil. Regarding detergent, they used only
natural soap made from the seeds of Vitellaria paradoxa.
Synthetic detergents were not popular in this village.
The family generally urinated outside of the concession but
sometimes urinated in the bathing area. They defecatedoutside or in the shared toilet, which was pit latrine, locatedabout 70 m from the house. They were constructing theirown new pit latrine, however the construction was stopped
because of limited money.

3.1.3. Agriculture in the household
Mr. OP’s family cultivated crops, such as millet, sorghum,
and corn in the farmland around the concession. This was themain food for this family. Water supply for crops was onlyrainfall. No fertilizer was used except for compost madefrom agricultural waste.
The family also cultivated vegetables, such as tomato,
onion, eggplant, green pepper in two vegetable gardens; asmall one (6 m × 10 m approximately) near the shallow well,and a larger one in the reservoir side (area is unknown). They
used chemical fertilizer for vegetable gardens; 300 kg/year of
NPK fertilizer containing 15% of N, 6.5% of P and 12% of K
respectively and 100 kg/year of urea fertilizer containing 46%of N. Both fertilizers were popular and sold in general stores.
The price, Mr. OP bought was 17,500 FCFA/50 kg(approximately 3,500 JPY/50 kg) and 15,000 FCFA/50 kg(approximately 3,000 JPY/50 kg) respectively. There was norecord of yield amount and price. Only for tomato and onion,
which were main products, we could estimate by roughamount and price range of last year. Estimated annual sales
value was 225,000 to 525,000 FCFA for tomato, and 150,000
to 550,000 FCFA for onion.
3.1.4. Material flow
Figures 5 and 6 show schematic views of the material
flow of water and phosphorus respectively. Each flow value
was estimated from interview and reference (Lopez, 2004).
Although there are some unknown values, the following areshown; the volume of disposed water is comparable to that ofirrigation water in a small vegetable garden, and phosphorus
disposed as urine or feces is comparable to the total amount ofprovided phosphorus as fertilizer.
3.2. Agricultural activity survey
Table 1 shows characteristics of four vegetable gardens.
In all sites, vegetables were cultivated with both chemicalfertilizer and livestock waste. Cultivation season was from
October or November to May or April in all sites. It almost
corresponds to the dry season. Vegetables were bought bybroker who came to buy, in all sites.
Table 2 shows one example of annual price fluctuation
obtained by interview. Price rises at the beginning and theend of the dry season. It corresponds to the season vegetables
cannot be harvested in the above mentioned schedule.

Vegetable Garden (2)Crop Field

Vegetable Garden (1)Household

2.4 – 4.9

Deep Well

4.26

Kitchen
Bathingurine

defecation

2.0 – 4.50.37

0.04

Shallow well
Unit: m3 year-1 capita-1

Fig. 5. Material flow in Mr. OP’s household (water volume).
Reservoir
Vegetable Garden (2)Crop Field

3.0

MarketVegetable Garden (1)1.9 – 2.3

Household
Kitchen
Bathing

Deep Well

urine

defecation

0.3 – 0.7

1.6

Shallow well
Unit: kg year-1 capita-1

Fig. 6. Material flow in Mr. OP’s household (Phosphorus).
Table 1. Material flow
WatersourceChemicalfertilizer

ManurePesticide

Vegetable

Site ARiver

Use

livestock
waste

Use

L, CbgSite B

shallow well

Use

Livestock
waste +city waste

Use

T, L, B

Site C

shallow well

UseLivestock
waste

Use

L, Cbg, T, O,Crt, B

Site D

shallow well

UseLivestock
waste

Use

L, Cbg, O,Crt, E, S

L: Lettuce, Cbg: Cabbage, T: Tomato, B: Bronble
O: Onion, Crt: Carrot, E: Egg plant, S: Strawberry

Table 2. Example of annual fluctuation of vegetable price.
Jan Feb
Pricecheap

Onion

4,000 10,000
FCFA/bag*Tomato3.3. Effect estimation
3.3.1. Graywater reuse
All parts of graywater was disposed to the ground directly.
If all of these graywater were reused for vegetable garden,
available amount is 85 to 185 L/day, from which was deducted
the estimated drinking amount of 1 L/person/day for 15

Reservoir

RainMarAprwellMay JunJul

Aug Sep Oct

Expensive?

Expensive

Nov Decwellcheap

25,000-30,000
FCFA/bag*

3,500
FCFA/20L

10,000
FCFA/20L

Lettuce

4,000
FCFA/area(1.5×10 m)

7,500
FCFA/area(1.5×10 m)

Blonble1,000
FCFA/area(1.5×10 m)

2,000
FCFA/area(1.5×10 m)* Carmers were using plastic bags for 50 kg of chemical fertilizerTable 3. Current fertilizer use and potential of urine.
NP(kg/year)(kg/year)

K (kg/year)

Current use of chemical fertilizer
NPK fertilizer ×300kg/year

4520

UREA fertilizer ×100kg/year

46037
0T otal91

2037

Individual

3.2

0.29 – 0.73

0.99

Household total (15 person)48

4.4 - 11

15Percentage vs current use

53%

22～56%

40%

Urine contents

persons from total water use. Required amount of water for 1
m2 vegetable garden was estimated as 5 L/day/m2, withfollowing to FAO manual (Brouwer and Heibloem, 1986) andassuming tomato cultivation under the dry season of Burkina
Faso. This amount roughly corresponds to currently supplying
amount (4.6 L/day/m2) estimated from the interview result.
As a result, additionally available vegetable garden isestimated as 17 to 37 m2. This area corresponds to only 1/3 to
1/2 of Mr. OP’s smaller vegetable garden, however, he canirrigate through a year to the vegetable garden near his house.
This gives a chance for Mr. OP to sell vegetables in a better
price. Of course, some treatment should be done forgraywater to avoid growth inhibition of vegetables and healthrisk for vegetable consumers. Slanted soil treatment system,
which requires no energy consumption and low initial cost, isone of candidate technologies. Ushijima et al. (2011)
reported that the slanted soil system achieved enough treatment
performance to avoid above mentioned two problems.
Therefore, the balance of initial cost of this system in Burkina
Faso and expected income increase by graywater reuse is thekey issue to be discussed in the future.
3.3.2. Urine utilization for vegetable garden
In this article, as a potential evaluation, nitrogen (N),phosphorus (P), potassium (K) amounts are compared between
currently used chemical fertilizer and urine, which contains
few pathogens in general. Table 3 shows the results.
Regarding to N and P, almost 1/2 can be replaced by urine.
Regarding to P, 1/5 to 1/2 can be replaced by urine. A largepart of P is discharged as feces (1.6 kg/year) (Lopez, 2004),
therefore if feces is added in safe way such as compost, about
70% of P can be replaced by urine and feces in maximum.

4. Conclusion
Based on detailed interview, the effect of a resource
recycling sanitation system application was estimated asfollows. Urine can replace almost half of chemical fertilizer.
Graywater reuse allows this household to expand vegetablegarden only 17 to 37 m2 however, it can irrigate through a year
to the garden near from house. This may enable to cultivate
in different schedule from general one, and farmer can cultivateand sell more strategically.
Acknowledgement
This study is part of joint work with Prof. Fumiko
Hakoyama (Fuji Women’s University), Prof. Takako Nabeshima(Hokkaido University) and International Institute of Water andEnvironment. Authors thank for Mr. Nestor Ouedrago whohelped us as a guide and translator. This study was supported
by JST-JICA Science and Technology Research Partnership for
Sustainable Development: Improving Sustainable Water andSanitation System in Sahel Region in Africa, directed by Prof.
Naoyuki Funamizu.

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