Characterisation and Fertiliser Potential of Mechanically Dewatered Faecal Sludge from Anaerobic Digestion

Dennis Ofori-Amanfo (), Eugene Appiah-Effah, Barbara Gyapong-Korsah, Esi Awuah, Helen M. K. Essandoh, Miriam Appiah-Brempong and Issahaku Ahmed
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Dennis Ofori-Amanfo: Regional Water and Environmental Sanitation Center Kumasi, Department of Civil Engineering, Kwame Nkrumah University of Science and Technology (KNUST), University Post Office, PMB, Kumasi, Ghana
Eugene Appiah-Effah: Regional Water and Environmental Sanitation Center Kumasi, Department of Civil Engineering, Kwame Nkrumah University of Science and Technology (KNUST), University Post Office, PMB, Kumasi, Ghana
Barbara Gyapong-Korsah: Department of Occupational and Environmental Health and Safety, Kwame Nkrumah University of Science and Technology (KNUST), University Post Office, PMB, Kumasi, Ghana
Esi Awuah: Regional Water and Environmental Sanitation Center Kumasi, Department of Civil Engineering, Kwame Nkrumah University of Science and Technology (KNUST), University Post Office, PMB, Kumasi, Ghana
Helen M. K. Essandoh: Regional Water and Environmental Sanitation Center Kumasi, Department of Civil Engineering, Kwame Nkrumah University of Science and Technology (KNUST), University Post Office, PMB, Kumasi, Ghana
Miriam Appiah-Brempong: Regional Water and Environmental Sanitation Center Kumasi, Department of Civil Engineering, Kwame Nkrumah University of Science and Technology (KNUST), University Post Office, PMB, Kumasi, Ghana
Issahaku Ahmed: Sewerage Systems Ghana Limited, Accra P.O. Box GP 1630, Ghana

Waste, 2025, vol. 3, issue 4, 1-17

Abstract: While mechanical dewatering is widely used in faecal sludge treatment, the agricultural potential of mechanically dewatered faecal sludge (MDFS) combined with anaerobic digestion (AD) remains underexplored, particularly in sub-Saharan Africa where nutrient recovery is critical for food security. This study provides the first comprehensive characterisation of MDFS from Ghana’s largest treatment facility and evaluates anaerobic digestion effectiveness for agricultural application. Over six months, 182 composite MDFS samples from Lavender Hill Faecal Treatment Plant were analysed for physicochemical properties, nutrients, heavy metals, and microbial contaminants before and after AD treatment. MDFS demonstrated exceptional nutrient density, with total nitrogen (2141.05 mg/kg), phosphorus (190.08 mg/kg), and potassium (4434.88 mg/kg) concentrations comparable to commercial organic fertilisers. AD achieved significant pathogen reduction, decreasing total coliforms from 148,808.70 to 493.33 cfu/100 g ( p < 0.001) and Ascaris lumbricoides eggs from 12.08 to 3.33 eggs/L, while maintaining nutrient integrity and keeping heavy metals within safe agricultural limits. Statistical modelling revealed a significant correlation between treatment duration and pathogen reduction efficiency. Despite substantial improvements, treated MDFS still exceeded some regulatory thresholds, indicating a need for complementary post-treatment strategies. This research establishes AD as an effective primary treatment for converting MDFS into a nutrient-rich organic fertiliser, supporting circular economy principles in urban sanitation systems and providing a sustainable pathway for agricultural nutrient recovery in resource-constrained settings.

Keywords: faecal sludge; anaerobic digestion; organic fertiliser; pathogen reduction; circular economy (search for similar items in EconPapers)
JEL-codes: Q1 Q16 Q18 Q2 Q20 Q23 Q24 Q25 Q28 Q3 Q31 Q38 Q5 (search for similar items in EconPapers)
Date: 2025
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