Enhancing Biological Nitrogen Removal of Slaughtering and Meat Processing Wastewater in Tertiary Ao Process by Influent Allocation: From Lab-Scale to Full-Scale Investigation

Abstract

Tertiary anoxic/aerobic (AO) process is promising for efficient nitrogen removal from high-strength wastewater. Little is known about mechanisms for influent allocation mode enhanced nitrogen removal and its optimization strategy in tertiary AO processes. Herein, the effects of influent allocation modes (50/40/10 vs. 50/25/25) on nitrogen removal performance were investigated from lab-scale to full-scale tertiary AO processes. Compared to 50/25/25, the allocation mode of 50/40/10 achieved an enhanced nitrogen removal of 97.7% (by 3.6%) and adaptability to ammonia load. This was ascribed to enhanced denitrification in the second anoxic tank and improved buffer ability in the third anoxic tank due to the optimized C/N ratios via influent allocation. The influent allocation mode had no significant effect on the relative abundance of nitrifying bacteria, but obviously enriched denitrifying and organic-degrading bacteria such as Nitrincola, Comamonas, Proteiniclasticum, and Thauera. Also, the community diversity and nosZ abundance were significantly increased. The reliability of 50/40/10 was verified in a 35,000 m3/d full-scale engineering, with effluent compliance and stable operation achieved within 48 days. This study provides a valuable reference for effective regulation of tertiary AO process.

Keywords: slaughtering and meat processing wastewater, tertiary AO process, influent allocation, nitrogen removal, full-scale application