Anaerobic co-digestion of Fecal Sludge and cabbage waste for biogas production: a bioinformatics approach

Abstract

In Sub-Saharan African urban settings, organic waste management and improper disposal of fecal sludge pose critical threats to human health and environmental well-being. Both challenges demand urgent attention and tailored solutions to mitigate their adverse impacts. This research focuses assessing the efficiency of the Thermophilic Anaerobic Digestion (TAD) process for treating FS, co-digesting it with Cabbage Waste (CW) to produce biogas for energy and nutrient-rich bio-slurry for crop cultivation at the same time. 20-liter laboratory batch reactors made of stainless steel for the inner and mild steel for the outer layer with suitable arrangements for feeding, gas collection, and draining of residues were used at a working volume of 18 liters to investigate four substrate ratios: 50F:50C, 75F:25C, 25F:75C, and 100F (FS and CW). A 35-day experiment was done and pH, nutrients (N, P, K, OC), heavy metals, gas composition and volume of gas were all examined. The results showed pH values ranging from mildly acidic to alkaline (6.02 to 8.05), and various nutrient compositions in the mixtures. Biogas composition analysis showed methane levels between 6% and 69.3%, while carbon dioxide levels ranged from 11% to 62.8%. The 75F:25C mixture yielded the highest biogas volume with values greater than or equal to 1 l/day and methane percentage. The respective methane percentages for Weeks 1 through 5 were 21.1%, 61.1%, 57.2%, 62.8%, and 55.3%. The study also highlighted the potential of using digestate as organic fertilizer due to low concentrations of heavy metals (Pb and Cu).