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In low-income countries, the discharge of untreated fecal sludge directly into the environment is a common practice that poses a threat to both environmental and public health. Planted drying beds (PDBs) are a promising and low-cost option for treating fecal sludge. Therefore, in Africa, the use of PDBs for treating fecal sludge is increasingly valuable due to the technology's high efficiency, especially in tropical climates. This paper presents a literature review on the use of PDBs for treating fecal sludge in Africa, focusing on current research requirements and directions. This review shows that Echinochloa pyramidalis appears to be the most effective indigenous species used for this purpose, while also highlighting the lack of stability in the design and implementation models of PDBs. Standardizing and generalizing implementation methodologies for PDBs in Africa, researching new native and efficient species, and testing combinations of different species in the beds would all be beneficial. HIGHLIGHTS Echinochloa pyramidalis has emerged as the most effective indigenous species used in the African context.; It is recommended to prioritize the identification of new native species that exhibit high efficacy for future research.; The current use of planted drying beds for fecal sludge treatment does not allow for direct disposal of percolates in the environment.;

Due to costs of setting up and operating electrical stirring systems to keep algae in suspension and exposed to light, cultivation of monospecific algae is poorly expanded in developing countries. However, some algal species, such as Arthrospira platensis, are equipped with gaseous vesicles that allow them to stay afloat and increase their exposure to light. In this study, we investigated in an unstirred outdoor environment, its growth kinetic and purifying performance in a brewery effluent-based media. Batch cultures were carried out in three experimental treatments and evolution of physicochemical and growth parameters were monitored. Then its contribution to depollution was determined. Results show that optimal conditions for producing A. platensis include the culture tank transparency, the effluent dilution (i.e. 10%), and the culture media amendment with sodium bicarbonate and sodium nitrate. The average productivity recorded reached 0.55 g DW·L−1·d−1 during the exponential growth phase, while preserving culture from contamination. COD and total nitrogen concentrations were reduced to 32.5 and 64.91%. Such results open up prospects for low-cost production of certain algae, in transparent and relatively high barrels, thus breaking the classic barriers related to shallow basin depth and mechanical agitation traditionally considered as critical to the success of algal production. HIGHLIGHT These results open up prospects for low-cost production of certain algaes such as spirulina, in transparent and relatively high barrels, thus breaking classic barriers related to shallow depth of the basins and mechanical agitation traditionally considered in order to succeed in algal production.; Furthermore, valorisation of agri-food industrial effluent contribute to lower production cost and depollute the wastewater.;

Valorisation of the supernatant of brewery effluent in plankton production for fish farming: an alternative for environment protection in southern countries Description of the subject. Identifying optimal conditions for the use of brewery effluents in phytoplankton production. Objectives. To determine the nutrient potential of the supernatant of this effluent, conditions for its use in phytoplankton production and the depollution that results from its use. Methods. Firstly, the supernatant of the effluent was analyzed. Five triplicate treatments were then seeded with Scenedesmus quadricauda, and followed for 27 days through measurements of biomass and physicochemical parameters. Finally, abatement rates of the initial polluting loads were determined. Results. Although the supernatant does not comply with the Benin standard, it does have a high nutrient potential. Not neutralizing the acidic initial pH led to a delay in algal growth. The treatment that contained 10% supernatant presented the highest algal production and significant reductions in polluting loads. Conclusions. In contexts where there is no functional wastewater treatment plan, it would be interesting to set up a win-win partnership between breweries and fish farmers. Optimal conditions would include optimal dose and prior pH neutralization.