Biogas production from water hyacinth in a novel anaerobic digester: A continuous study

Abstract

Mixing and the separation of stages in a digester during anaerobic digestion demonstrate enhanced biodegradation efficiency of the feedstock. But two stage anaerobic digesters are difficult to operate and require huge space. Also, continuous high intensity mixing minimises biogas production. Based on these criteria, a novel type of two stage anaerobic digester was designed. The aim of this study was to evaluate the performance of this novel anaerobic digester in continuous mode utilising water hyacinth as the feedstock. Initially, untreated water hyacinth whole plant was fed in the digester followed by hot air oven pretreated water hyacinth and water hyacinth co-digested with food waste. The optimal OLR for untreated and pretreated water hyacinth was observed to be 3.75 kg COD/m3.d whereas for co-digested water hyacinth the optimal OLR was 6.7 kg COD/m3.d; illustrating an average COD removal of 72.5%, 82% and 77% for untreated, pretreated and co-digested water hyacinth respectively.