New insights on the sludge fermentation liquid driven denitrification: Evaluation of the system performance and effluent organic matter (EfOM)

Sludge fermentation liquid (FL) is a promising and sustainable carbon source for biological denitrification. In this study, four types of FLs were prepared using different chemical treatments to enhance denitrification. The profile of effluent organic matter (EfOM) were evaluated. Results indicate that the FLNaOH (NaOH treatment at pH 10) contained the maximum amount of soluble organics, but led to the worst nitrate removal performance. Nitrate removal efficiency with FLcontrol was much higher than that of FLCaO2, FLCa(OH)2, and FLNaOH. On the other hand, it was found some organics in FL was hard to be utilized by denitrifiers. In particular, EfOM with FLNaOH presented the highest building blocks, high molecular weight (HMW) protein and HMW polysaccharide. It also contained much higher C-(C/H) group. This study provided a new insight on the FL driven denitrification. The necessarity of pursuing the alkali pretreatment to produce carbon source were discussed and evaluated.