Impact cassava residue on ammonia emission and microbial communities during sewage sludge cocomposting process

In this study, the impacts of cassava residue as a bulking agent and carbon source on sewage sludge composting were evaluated in lab-scale reactors. Three composting experiments were carried out with different ratios of sewage sludge and cassava residues: R1 (400 g sewage sludge), R2 (375 g sewage sludge, 25 g cassava residue), and R3 (350 g sewage sludge, 50 g cassava residue). Compared to the R1 reactor, the temperature of R2 and R3 increased rapidly. The cumulative ammonia emission of R1 was 597.14 mg L-1, while R2 and R3 were 347.59 and 451.06 mg L-1, respectively. Therefore, cassava residue could be used to reduce NH3 emission during sludge composting. Furthermore, the maximum protease activates (observed on day 10) for R1, R2, and R3 were 24.61, 31.78, and 36.12 U g(-1), respectively. The maximum urease activities for R1, R2, and R3 was recorded as 20.05 U g(-1) (day 5), 12.53 U g(-1) (day 5), and 15.93 U g(-1) (day 10). Addition of cassava residue also contributed to positive shifts in the bacterial community. High-throughput sequencing analysis showed that in the R2 reactor, Actinobacteria was present in relatively high abundance. Actinobacteria positively correlates with TN and has the effect of biological nitrogen fixation. (c) 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901-1907, 2018