Iron flocculation stimulates biogas production in Microthrix parvicella-spiked wastewater sludge

Municipal wastewater sludge has been used for fertiliser and biogas production for several decades. Chemical compounds such as iron and aluminium are common coagulants used in wastewater treatment plants to remove suspended solids, phosphorus and micro-organisms. This laboratory study explores whether ferric chloride (FeCl 3 as PIX-111) or aluminium chloride (AlCl 3 as PAX-18) flocculation could stimulate biogas production in wastewater sludge contaminated with Microthrix parvicella . In a fermentation process run in three replicates, cumulative methane production was in average about 25 % higher using the iron flocculated sludge than using the aluminium flocculated sludge; this difference was statistically significant ( P