## 3 Results and Discussion
### Potential Applications of Biochar in the NEA
Concerning the soil as an environmental resource, the use of biochar for amendment purposes can contribute to the sustainability of farming systems [23]. In the context of the circular economy, the use of biochar to amend soils is also a contribution toward the recycling of soil nutrients [103; 104]. For instance, a published study that was made using samples collected in the analyzed processing centers as feedstock to produce biochar showed that the content of inorganics in ash after the pyrolysis process increases from 7.1 wt.% in the raw feedstock to 15 wt.% in the resulting coffee husk biochar [29]. The major components within the inorganic content of the biochar made from coffee husks are elements of relevance to soil fertility, namely, potassium (52 wt.%), phosphorous (5 wt.%), calcium (13 wt.%), and silicon (15 wt.%) [105]. These elements are taken from the soil during the growth of the coffee trees and, if not returned to the soil, have to be added by the farmers via synthetic or organic fertilizers. Nonetheless, the effective incorporation of minerals embedded in the biochar matrix into the soil depends on biogeochemical cycles. Thus, it may take decades until these nutrients are available to the plant roots [106]. Considering the importance of the minerals and carbon embedded in the biochar for the soil, the use of coffee husk biochar in a sector other than that of agriculture (e.g., infrastructure, energy) can cause the loss of these nutrients. In the case of the energy sector, recycling the ashes after the combustion of biochar back to the soil should be organized to avoid the loss of minerals in the soil. This implies that biochar should not optimally be transported out of the region/country for its energy conversion. Furthermore, there should be a protocol for the return of ashes back to the farms. With respect to the energy sector, the process proposed here produces thermal energy during the carbonization of agricultural waste (Criteria 5, Table 1), and its recovery can replace the subsidized fossil fuels that are currently used by farmers' cooperatives for drying coffee fruits and cocoa grains (Figure 4). In this way, the use of this pyrolysis process by farmers' cooperatives can reduce their consumption of fossil fuels and their dependence on government subsidies (Section 3.2). Biochar has also important properties for the environmental management of water. Application of biochar to soil increases its water-holding capacity, which would be very appropriate in abundant dry areas of Ecuador on the coast and in the Andes, to reduce the need for irrigation water and to mitigate the impact of droughts. However, this would require transport and would lead to the transfer of carbon and nutrients between regions. Biochar can also be used as filtering media in environmental remediation processes of contaminated drinking water or sewage [42; 76; 81; 84]. Thus, the production of biochar in farmers' cooperatives can be a contribution to the efficient and sustainable use of water resources. Green infrastructure represents an intersection of the use of biochar as a soil amendment, water resources, and urban development. The increasing urbanization rates in the NEA, together with the heavy local rains, require sustainable alternatives to control runoff water. Roof-top and vertical gardens are alternatives currently considered by urban planners as strategies to manage stormwater runoff in cities. Unlike rainwater gardens or ponds, roof-top and vertical gardens do not require valuable urban land. The use of biochar in roof-top and vertical gardens, in addition to the benefits for growing of plants (Table 4), increases the water-holding capacity of the substrate, thus retaining more stormwater with less structural weight loading. Likewise, the use of biochar expands the diversity of plants that can be planted in these gardens to include species with higher water demand [95].