Improved pyrolysis for sewage sludge valorization via enhanced microcosm vermicomposting

The addition of plant-derived bulking amendments to substrates in sewage vermicomposting provides an improved resource recovery technique for compost production. Producing biochar from these enhanced vermicompost through slow pyrolysis is a value-added approach to recycle the organic waste and has the potential of guaranteeing a complete removal of pathogens. The study assessed the potential use of coconut coir, palm coir and sawdust as bulking amendments in an enhanced vermicomposting and investigated the influence of these enhanced vermicomposting on the quality of biochar produced via slow pyrolysis. Results revealed that the enhanced vermicomposting improved the vermiculture of E. foetida and significantly reduced the worm mortality (< 10%). The biochar produced from the enhanced vermicomposting exhibited desired physicochemical characteristics where the coconut coir treatment demonstrated the highest yield (41.65 ± 0.76%) compared to the palm coir (35.32 ± 2.07%) and sawdust (33.18 ± 0.37%). The slow pyrolysis of the enhanced vermicompost also demonstrated a complete pathogen removal (100%) in terms of total coliform and E.coli.