Influence of the mixing ratio on the anaerobic co-digestion of municipal biowaste with domestic wastewater sludge on methane production

Anaerobic co-digestion (A-Co) is a viable option to overcome the disadvantages of mono-digestion. This research presents the results of biochemical methane potential assays (BMPs) assessing the A-Co of municipal biowastes (MBW) from one city which perform source separation and selective collection with domestic wastewater sludge (DWS) from a municipal wastewater treatment plant (WWTP) in different DWS: MBW mixing ratios. Besides methane production, it was evaluated the hydrolysis (through a first-order kinetics model and the modified Gompertz model), since this is the limiting step of the A-Co of solid wastes. The results showed that A-Co of DWS with MBW is feasible and that DWS: MBW mixing ratio generated a synergistic effect in the process. The mixing ratio DWS:MBW that produced the largest quantities of methane (105.6 mLCH4·gVS-1), optimal hydrolysis constants (Kh) and shortest lag phase (under 3.3 days) was 20:80.