Pilot-scale anaerobic co-digestion of municipal biomass waste and waste activated sludge in China: Effect of organic loading rate

The effects of organic loading rate on the performance and stability of anaerobic co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) were investigated on a pilot-scale reactor. The results showed that stable operation was achieved with organic loading rates (OLR) of 1.2-8.0 kg volatile solid (VS) (m(3) d)(-1), with VS reduction rates of 61.7-69.9%, and volumetric biogas production of 0.89-5.28 m(3) (m(3) d)(-1). A maximum methane production rate of 2.94 m(3) (m(3) d)(-1) was achieved at OLR of 8.0 kg VS (m(3) d)(-1) and hydraulic retention time of 15 days. With increasing OLRs, the anaerobic reactor showed a decrease in VS removal rate, average pH value and methane concentration, and a increase of volatile fatty acid concentration. By monitoring the biogas production rate (BPR), the anaerobic digestion system has a higher acidification risk under an OLR of 8.0 kg VS (m(3) d)(-1). This result remarks the possibility of relating bioreactor performance with BPR in order to better understand and monitor anaerobic digestion process. (C) 2012 Elsevier Ltd. All rights reserved.