Non-Saturated Flow Drying Beds permit the effective treatment of septic tank discharge sludge. However, they are vulnerable to clogging. To ensure the sustainability of this technology, through the choice of a suitable filter bed, an unsaturated flow model coupled with the variation of the biofilm has been developed. Calibration, validation and comparison of model simulation results and experimental results were performed on the basis of the NASH criterion. The simulations covered three types of sand: fine sand, medium sand and coarse sand. The results show that the maximum organic load applicable is 24.7 mgO2 / cm2 / day at the fine sand, 43.3 mgO2 / cm2 / day at the medium sand and 31.6 mgO2 / cm2 / day at the level of the sand coarse sand. Then, the Chemical Oxygen Demand removal yield is 92 % at the medium sand level versus 73 % for the coarse sand. Finally, medium sand is less vulnerable to clogging (91.3 %) than fine sand (95.45 %). So, of the three types of sand, it is the average sand that is best suited for the treatment of sludge septic tanks by Non-Saturated Flow Drying Beds. However, when the average sand is not available, the developed model makes it possible to fix the operating conditions and the purification yields of the available sand.

In the perspective of exploiting the economic opportunities for the recovery and reuse of waste as resources, our study aims to promote sanitation and improve agricultural productivity. It was assessed by collecting urine from households and drinking establishments in Katiola city, Toumbokaha and Kassémé villages and its use as a fertilizer. A total of 25 drinking alcohol operators and 258 households have agreed to install urine production equipment. They provided about 2.500 and 32.000 liters of urine per month. Studies have shown that wastewater facilities installed in households are more effective in providing urine through their frequent and regular use. Thus, households are more efficient in providing urine (more than 12 times) than public places. This means that individual sanitation is more effective than collective sanitation. These collected urines are hygienized by storage and applied as fertilizer to rice fields. The yields of urine fertilization are higher than those of chemical fertilizer fertilization, with the added benefits of herbicide. While improving rice productivity and thus soil fertility, urine ensures the sustainability of rice-based systems at economically bearable costs by producers. These results are an expression of the accession of the populations, a guarantee of the sustainability of the EcoSan approach, through their involvement in the production, collection and use of urine as fertilizer.