Vermicomposting as an effective approach to municipal sewage sludge management through optimization of the selected process variables

• Published in: Water science and technology Vol. 88; no. 8; pp. 1957 - 1973
• Main Authors: Banda, Beauty, Habtu, Nigus Gabbiye, Gebreeyessus, Getachew Dagnew, Meshesha, Beteley Tekola
• Format: Journal Article
• Language: English
• Published: London IWA Publishing 15.10.2023
• Subjects: Agriculture; coffee husks; Composting; cow dung; Design; Developing countries; eisenia fetida; LDCs; Mixing ratio; Moisture content; municipal sewage sludge; Municipal wastes; Municipal wastewater; Nitrogen; Onsite; Phosphorus; Potassium; Process variables; Response surface methodology; Sanitation; Sewage; Sewage sludge; Sludge; Substrates; Sustainability management; Vermicomposting; Water content; Water treatment; Worms; Ethiopia; Africa; Addis Ababa Ethiopia
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2023.322

Abstract In most developing countries, municipal sewage sludge end-use practices appear unsustainable; rather, it poses environmental concerns. This study examined the potential of vermicomposting of municipal sewage sludge and its blend with other biowaste for agricultural application. Using a response surface methodology and the Box–Behnken design in Design Expert Software (Version 10.0.7), the current study optimized the moisture content (60–90%), turning frequency (1–3 turnings/week), and substrate mixing ratios (50:50 to 80:20 wt.%) to maximize the content of nitrogen, phosphorus, and potassium. As a result, an optimal moisture content (72%), substrate mixing ratio (72.34:27.6 wt.%), and turning frequency (2 per week), producing a promising-quality vermicompost with a maximum yield of nitrogen (2.76%), phosphorus (1.80%), and potassium (1.88%) is achieved. Thus, vermicomposting can effectively turn the concerning municipal sewage sludge into useful agricultural input for its sustainable management.