Results from FaME (Faecal Management Enterprises) - can dried faecal sludge fuel the sanitation service chain?

In Sub-Saharan Africa, sanitation needs for the majority of the urban population are met by onsite sanitation technologies. Cities grapple with management of faecal sludge (FS) once these technologies become full, while at the same time the urban economy is resource intensive. The FaME (Faecal Management Enterprises) project addressed both of these issues by identifying untapped markets for FS treatment products. Industries have a high fuel demand and FaME demonstrated that dried FS could be used as a solid combustible in industrial kilns. Existing treatment technologies were adapted for fuel production, and its application was demonstrated in two pilot kilns. Historically used as a soil conditioner, processing of FS to a solid biofuel could provide higher revenues, thereby providing a financial incentive for stakeholders to enhance FS management service along the entire sanitation chain

SEEK (Sludge to Energy Enterprises in Kampala): co-processing faecal sludge for fuel production

The goal of this project was to improve the resource-recovery value of faecal sludge treatment products. A market assessment identified coffee husks, spent grain, and sawdust as optimal organic wastes to coprocess with faecal sludge to increase its fuel value. Drying times of faecal sludge to 90% solids were reduced by half with co-pelletizing with these organic wastes. Briquettes produced with char had comparable heating value, fuel performance, and emissions to charcoal briquettes currently being sold. Use of pellets as a fuel was tested in a gasifier and in several industrial clay kilns (after crushing). High ash content led to clinker formation in the gasifier, but performed well in kilns. The potential market for co-processed faecal sludge fuels is high in Kampala, Uganda, especially among industries, however, the market for pellets needs to be developed

Locally produced natural conditioners for dewatering of faecal sludge

<p>In urban areas of low-income countries, treatment of faecal sludge (FS) is insufficient or non-existent. This results in large amounts of FS being dumped into the environment. Existing treatment technologies for FS, such as settling-thickening tanks and drying beds, are land intensive which is limiting in urban areas. Enhanced settling and dewatering by conditioning was evaluated in order to reduce the treatment footprint (or increase treatment capacity). Conventional wastewater conditioners, such as commercially available lime and polymers, are expensive, and commonly rely on complex supply chains for use in low-income countries. Therefore, the treatment performance of five conditioners which could be produced locally was evaluated: <i>Moringa oleifera</i> seeds and press cake, <i>Jatropha curcas</i> seeds, <i>Jatropha Calotropis</i> leaves and chitosan. <i>M. oleifera</i> seeds and press cake, and chitosan improved settling and dewatering and had a similar performance compared to lime and polymers. Optimal dosages were 400–500 kg <i>M. oleifera</i>/t TS, 300–800 kg lime/t TS and 25–50 kg polymer solution/t TS. In comparison, chitosan required 1.5–3.75 kg/t TS. These dosages are comparable to those recommended for wastewater (sludge). The results indicate that conditioning of FS can reduce total suspended solids (TSS) in the effluent of settling-thickening tanks by 22–81% and reduce dewatering time with drying beds by 59–97%. This means that the area of drying beds could be reduced by 59–97% with end-use as soil conditioner, or 9–26% as solid fuel. Least expensive options and availability will depend on the local context. In Dakar, Senegal, chitosan produced from shrimp waste appears to be most promising.</p

Data_Sheet_1_Residues from black soldier fly (Hermetia illucens) larvae rearing influence the plant-associated soil microbiome in the short term.pdf

The larvae of the black soldier fly (BSFL, Hermetia illucens) efficiently close resource cycles. Next to the nutrient-rich insect biomass used as animal feed, the residues from the process are promising plant fertilizers. Besides a high nutrient content, the residues contain a diverse microbial community and application to soil can potentially promote soil fertility and agricultural production through the introduction of beneficial microbes. This research assessed the application of the residues on plant-associated bacterial and fungal communities in the rhizosphere of a grass-clover mix in a 42-day greenhouse pot study. Potted soil was amended with BSFL residues (BR+) or conventional compost (CC+) produced by Rwandan waste management companies in parallel to residues and compost sterilized (BR-, CC-) by high-energy electron beam (HEEB) as abiotic controls. The fertilizers were applied at a rate of 150  kg N  ha−1. Soil bacterial and fungal communities in both fertilizer and soil were assessed by high-throughput sequencing of ribosomal markers at different times after fertilizer application. Additionally, indicators for soil fertility such as basal respiration, plant yield and soil physicochemical properties were analyzed. Results showed that the application of BSFL residues influenced the soil microbial communities, and especially fungi, stronger than CC fertilizers. These effects on the microbial community structure could partly be attributed to a potential introduction of microbes to the soil by BSFL residues (e.g., members of genus Bacillus) since untreated and sterilized BSFL residues promoted different microbial communities. With respect to the abiotic effects, we emphasize a potential driving role of particular classes of organic matter like fiber and chitin. Indeed, especially taxa associated with decomposition of organic matter (e.g., members of the fungal genus Mortierella) were promoted by the application of BSFL residues. Soil fertility with respect to plant yield (+17% increase compared to unamended control) and basal respiration (+16% increase compared to unamended control) tended to be improved with the addition of BSFL residues. Findings underline the versatile opportunities for soil fertility arising from the application of BSFL residues in plant production and point to further research on quantification of the described effects.</p