Efficient partial nitritation performance of real printed circuit board tail wastewater by a zeolite biological fixed bed reactor

Abstract

At present, low-carbon treatment of printed circuit board (PCB) tail wastewater by anammox process had not been reported. Stably produced nitrite instead of nitrate was the key to anammox process. In this study, a zeolite biological fixed bed (ZBFB) reactor was started up to investigate the partial nitritation (PN) performance for the treatment of synthetic wastewater and PCB tail wastewater, with ammonium concentration of 100 and 105 mg/L, respectively. ZBFB presented stable nitrite accumulation rate (NAR) of 98.20 % and 97.61 % during the biological desorption stage, respectively. The PN mechanism was proven as the free ammonia (FA) inhibition, which was maintained by the continuous desorption of ammonium from zeolite. Although PCB tail wastewater showed strong inhibition on bioactivity, stable and efficient nitrite accumulation was obtained. The average nitrite producing rate (NPR) was 0.816 and 0.352 kg N/(m3·d), separately. The secretion of extracellular polymeric substances (EPS) decreased. High-throughput sequencing analysis results further presented the enrichment of ammonia oxidizing bacteria (Nitrosomonas) in ZBFB. The enrichment of denitrifying bacteria (Thauera) indicated the occurrence of simultaneous partial nitritation and denitrification (SPND). These results meant a novel and reliable PN method by ZBFB for real wastewater was feasible, which further promoted the development of energy-saving anammox process in industrial wastewater treatment.