Recycling of Faecal Sludge: Nitrogen, Carbon and Organic Matter Transformation during Co-Composting of Faecal Sludge with Different Bulking Agents

Abstract

This study investigated the effect of locally available bulking agents on the faecal sludge (FS) composting process and quality of the final FS compost. Dewatered FS was mixed with sawdust, coffee husk and brewery waste, and composted on a pilot scale. The evolution of physical and chemical characteristics of the composting materials was monitored weekly. Results indicate that bulking agents have a statistically significant effect (p < 0.0001) on the evolution of composting temperatures, pH, electrical conductivity, nitrogen forms, organic matter mineralisation, total organic carbon, maturity indices, quality of the final compost and composting periods during FS composting. Our results suggest reliable maturity indices for mature and stable FS compost. From the resource recovery perspective, this study suggests sawdust as a suitable bulking agent for co-composting with FS—as it significantly reduced the organic matter losses and nitrogen losses (to 2.2%), and improved the plant growth index, thus improving the agronomic values of the final compost as a soil conditioner. FS co-composting can be considered a sustainable and decentralised treatment option for FS and other organic wastes in the rural and peri-urban communities, especially, where there is a strong practice of reusing organic waste in agriculture.

Faecal sludge emptying in Sub-Saharan Africa, South and Southeast Asia: A systematic review of emptying technology choices, challenges, and improvement initiatives

“…FS from lined pit latrines and septic tanks is less thick compared to that from unlined pit latrines. This is because unlined pit latrines allow for the exfiltration of the liquid fraction of FS into the surrounding soils through the permeable sidewalls and open bottom (Tilley et al, 2008;Manga et al, 2022a).…”

“…For Low-and Middle-Income Countries (LMIC), the most common types of sanitation facilities used by people are On-Site Sanitation (OSS) systems, which include pit latrines, flush toilets, aqua privies, and septic tanks (Afolabi and Sohail, 2016;Akumuntu et al, 2017;Manga, et al, 2019;Manga et al, 2022b). The use of OSS leads to the accumulation of Faecal Sludge (FS), which needs to be desludged and transported to the designated disposal sites or the FS treatment facilities for treatment before disposal to ensure the wellbeing of the users as well as the protection of the surrounding environment (Junglen et al, 2020;Manga et al, 2021;Manga et al, 2022a;Tokwaro et al, 2023). The emptying and transport of FS is carried out by a number of stakeholders which include the private sector, Non-Governmental Organizations (NGOs), local government and municipal authorities (Peal et al, 2014;Manga, 2017;Singh et al, 2021).…”

“…The use of OSS leads to the accumulation of Faecal Sludge (FS), which needs to be desludged and transported to the designated disposal sites or the FS treatment facilities for treatment before disposal to ensure the wellbeing of the users as well as the protection of the surrounding environment (Junglen et al, 2020;Manga et al, 2021;Manga et al, 2022a;Tokwaro et al, 2023). The emptying and transport of FS is carried out by a number of stakeholders which include the private sector, Non-Governmental Organizations (NGOs), local government and municipal authorities (Peal et al, 2014;Manga, 2017;Singh et al, 2021). For over two decades, the private sector has been more responsive than government to the gap in FS emptying and transportation (Bassan, 2014).…”

Application of black soldier fly larvae in decentralized treatment of faecal sludge from pit latrines in informal settlements in Kampala city

“…Application of decentralized (onsite) FS treatment facilities/ systems promotes initiatives which can allow FS to be emptied, treated and used at and/or near the point of generation leading to reduced transportation costs (Semiyaga et al, 2015). Several available options for decentralized treatment of FS such as composting, vermicomposting, anaerobic digestion, rendering have been applied for the treatment of FS (Cofie et al, 2009;Manga et al, 2021;Semiyaga, et al, 2022a;Manga et al, 2022b). However, these techniques have some limitations.…”

Biochar and Its Potential Application for the Improvement of the Anaerobic Digestion Process: A Critical Review

“…World Bank estimates show that in 2020, 2.24 billion tons of solid waste were generated globally, and it is envisaged that this number will rise by 73% to 3.88 billion tons in 2050 [3]. The management and disposal of large quantities of waste is usually a source of environmental concern [4][5][6]. When not properly disposed of, solid waste, particularly the organic fraction, is of environmental concern as its decomposition leads to the release of methane, a powerful greenhouse gas that contributes substantially to global warming and climate change [7,8].…”