The development of efficient sanitation technologies and practices can enhance the resilience of local populations from adverse consequences related to the lack of appropriate sanitation. Many imported water and sanitation technologies have failed because they were not adapted to local conditions or did not correspond to the needs of end users. This project aimed to develop, under real conditions, sanitation technologies and resource recovery technologies in a participatory way to increase their robustness and acceptability by local beneficiaries.
The PI and his team worked to develop a greywater treatment unit to collect and treat household wastewater for reuse in gardening. A Slanted Soil Treatment System (SSTS) had been previously designed and tested for greywater treatment at the household level, but the quality of the treated greywater was not sufficient to allow its safe reuse in gardening. The current project tested modifications made to the treatment system, including the configuration of the SSTS, the characteristics of the filter bed, and addition of plants to enhance its efficiency, making possible the safe reuse of the treated water for food crop irrigation. In addition, a composting toilet with urine diversion had been developed previously for rural households. However, concerns related to the biodegradability of the organic matter, hygiene, and maturation of the compost have emerged. The PI and researchers in this project therefore tested test new strategies by mixing urine and feces in the dry toilet. In addition, they designed a composting pit for use as an additional step for the maturation and sanitization of the compost collected from the composting toilet, including through mixture with agricultural waste. The team also worked to identify the most efficient operating conditions allowing for the production of hygienic and nutrient-rich compost by testing several mixtures. They also studied the potential for thermal inactivation of pathogens using sunlight with the aim of making the compost safer and more acceptable to users.
The PI Dr. Maiga and his team developed two models of a complex shower room/greywater treatment system and constructed them for eight beneficiary households in two rural settlements. The greywater treatment system is a subsurface horizontal flow constructed wetland in the first model and a hybrid system (vertical flow filter followed by a subsurface horizontal flow wetland) in the second model. The treatment systems are designed to allow direct collection of shower greywater (including urine) into the upper basin of the pre-treatment stage. Dishwashing and laundry greywater are collected via a receiving basin (located inside the yard) and pass through the same piping to the treatment system (located outside the court yard and close to the shower room). Two plants were tested: vetiver (Chrysopogon zizanioides) and gamba grass (Andropogon gayanus). Visual observations of the treatment systems indicated they performed as expected. Chrysopogon zizanioides seemed more adapted to the greywater conditions than Andropogon gayanus. The results obtained from four households showed that the treatment systems perfomed well, reducing organic matter, nutrients, and fecal bacterial significantly. The residual concentration of fecal bacteria was compliant with the WHO reuse guidelines for restricted irrigation.
The composting toilet intended for the recovery of nutrient-rich compost for gardening was developed and constructed in eight beneficiary households, and the PEER team evaluated its performance. The excreta under maturation was transferred into composting pits in some of the households, and the sanitization is still ongoing. The households are using the facility, and it is contributing to reducing open defecation, which should reduce the dissemination of excreta related diseases.
The researchers also developed training manuals on the construction and operation of greywater and excreta recovery and treatment facilities. These materials will allow individuals or communities to understand the technical and operational aspects of the construction and operation of the facilities. The conditions for recovering sanitation by-products from a composting toilet or a treated greywater storage tank are also explained. The team also trained the beneficiary households on the operation and maintenance of the greywater and excreta recovery and treatment facilities developed under the project and how to collect and reuse treated greywater in gardening. During the training, the researchers also collected the views of the households on the sanitation facilities, the difficulties encountered, and suggestions for improvements.
Dr. Maiga had originally hoped that the outputs from both the greywater treatment and composting toilets could be used in gardening. For greywater, the results obtained from four households allow the reuse of the water in restrictive irrigation according to WHO standards. However, further improvements in the removal of microbial contamination are still required to make treated greywater even safer. The elimination of pathogens from the composting toilets was not so successful and took a long time, with the results varying seasonally. The team is still working to optimize the compositing pits and then test vegetables grown with such compost to ensure their safety before the compost could be promoted for this purpose.
In conclusion, the sanitation facilities developed in the project are very promising, but additional tests are needed to have definitive models. To know the real impact of this project, Dr. Maiga hopes to be able to conduct the compost reuse experiment for vegetable production, evaluate the associated risks, conduct an associated socioeconomic study, and increase the number of beneficiary households.
USAID, IRSAT, 2IE