Improvement of anaerobic co-digestion of plant waste and excess sludge using calcium peroxide

Abstract

Plant waste (PW) and excess sludge (ES) are two main organic matters of municipal solid waste. However, there are few reports on their anaerobic co-digestion. In this work, the mixed proportion of PW and ES anaerobic co digestion was rst optimized at mesophilic temperature, and then the anaerobic co-digestion of PW and ES was enhanced with strong oxidant calcium peroxide (CP). The results showed that the optimal mixing ratio of PW and ES was 1/1 (in terms of volatile solids), and the C/N of mixed digestion substrate was 23.5/1, the maximum methane production was 172.6 mL/g (in terms of volatile solids). CP could enhance methane production from anaerobic co-digestion of PW and ES. When the content of CP was 0.2 g/g (in terms of total suspended solids), the maximum methane production was 234.8 mL/g, about 1.4 times of the blank. The mechanism investigation showed that CP promoted the release of organic matter during the co-digestion, and the higher the content of CP, the greater the release of soluble chemical oxygen demand. The presence of appropriate amount of CP promoted the activities of key enzymes in anaerobic fermentation process, and then increased the e ciency of methane production. The results of this work provide an alternative strategy for the resource utilization of PW and ES.

Surfactant rhamnolipid promotes anaerobic codigestion of excess sludge and plant waste

“…The reduction rate of organic matter in the codigestion process is a key parameter to evaluate anaerobic efficiency (Duan et al 2012;Romero-Güiza et al 2016;Pei et al 2020;Lin et al 2021;Wang et al 2021b). As shown in Figure 3, the reduction rate of VSS in each reactor first increased with time, and the change of VSS was not very significant after about 20 days, which was consistent with the cumulative methane production in Figure 1.…”