Characteristics of free fermentation products from food wastes and its denitrification performance

Food wastes were used for free short-term anaerobic fermentation to prepare a carbon source for enhancing denitrification performance. The effect of initial solid concentration on the hydrolysis and acidogenesis products during 60 h of reaction was studied, and the results indicated that short-term fermentation led to an incomplete process, with the maximum organic acids content of (13±0.5)% occurring at the initial solid concentration (16.56 g·L^-1). The short-term fermentation liquid was a complex carbon source that included a large proportion of carbohydrates with some lactic, acetic, and butyric acids and proteins. The denitrification performance of the fermentation liquid was evaluated by a nitrate utilization rate (NUR)batch test and a COD/N of 6 was the optimum condition to obtain the lowest concentrations of nitrogen and COD in the effluent. Under this optimum condition, the denitrification performance parameters (with a denitrification rate V_DN=12.89 mg·(g·h)^-1(caculated by VSS) and a denitrification potential P_DN=0.174 g·g^-1 (caculated by COD) were obtained. The readily biodegradable substrates in the short-term fermentation liquid were 58.35%.