The effects of denitrification with sludge alkaline fermentation liquid and thermal hydrolysis liquid as carbon sources

Abstract

Nitrate removal using the sludge alkaline fermentation liquid and thermal hydrolysis liquid as external carbon sources was investigated in this study. The nitrate removal efficiency with sludge fermentation liquid was higher than that with sludge thermal hydrolysis liquid, and the specific denitrifying rates were 7.94 g per kg MLVSS per h (MLVSS is Mixed Liquor Volatile Suspended Solids) and 1.16 g per kg MLVSS per h, respectively. The utilization of dissolved organic matters (DOM) during the denitrification process was analyzed by three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy with fluorescence regional integration (FRI) analysis. The EEM fluorescence intensity of region I (tyrosine-like protein) and IV (soluble microbial by-product) all decreased with two kinds of sludge carbon sources. Furthermore, the consumption of soluble chemical oxygen demand (SCOD), volatile fatty acids (VFAs), protein and carbohydrate by the denitrifier during the denitrification process were also analyzed.