Denitrification performance using biodegradable polymer as carbon source to treat nitrified swine wastwater

Abstract

Abstract. The “solid-phase denitrification” is a much more promising type of heterotrophic biological denitrification compared with liquid carbon source or natural cellulose materials. The biodegradable polymers were used simultaneously as biofilm carrier and carbon source. Liquid carbon source addition needs a complicated and expensive control system process to avoid overdosing. Natural cellulose materials are much cheaper; however, it will bring the problem of high concentration of dissolved organic carbon and interference of color. Swine wastewater is characterized by a high concentration of ammonia nitrogen and low-level ratio of carbon to nitrogen (C/N), which results in a poor nitrogen removal performance through traditionally biological denitrification. Thus, it is necessary to investigate the feasibility of treatment of nitrified swine wastewater by solid-phase denitrification. In this study, the denitrification performance using three kinds of biodegradable polymers materials i.e., poly butylenes succinate (PBS), polyhydroxybutyrate valerate copolyesters (PHBV), polycaprolactone (PCL) were compared with each other and evaluated in terms of nitrate removal rate in batch operation model. Result shown that lag-time of denitification was shortest using PCL as carbon source, and nitrate removal rate reached greater than 95% with cultivation time of 20 days without accumulation of TOC and NH4+-N in effluent. Therefore, PCL has the potential to function as carbon source denitrification system treating nitrified swine wastewater under conditions in this study.