基于SNAD工艺的市政有机固废厌氧消化沼液脱氮研究OA

Mixed municipal organic solid wastes composed of food waste,sludge and feces generate large amounts of digestate after anaerobic digestion,characterized by high ammonium nitrogen and chemical oxygen demand(COD)concentrations and complex pollutant compositions,making it difficult for conventional biological treatment processes to achieve discharge standards.Therefore,a combined process of a two-stage simultaneous partial nitritation-anammox-denitrification integrated fixed-film activated sludge process coupled with an aerobic-anoxic-oxic membrane bioreactor(SNAD-IFAS+O/A/O-MBR)is proposed for the treatment of anaerobic digestion liquor from municipal organic solid wastes.The startup period of the process lasts 129 d,during which the dissolved oxygen concentrations in the two SNAD-IFAS stages are controlled at 0.02-0.30 mg/L and 0.01-0.50 mg/L,respectively.During 113-122 d,with an influent hydraulic retention time of 4 d,the average total nitrogen removal efficiency of the two-stage SNAD-IFAS process reaches approximately 80％.After further treatment by the O/A/O-MBR,the effluent total nitrogen concentration is below 10 mg/L and the COD concentration is lower than 270 mg/L.High-throughput sequencing results show that the relative abundance of ammonia-oxidizing bacteria(3.56％)in SNAD1 is much higher than that of nitrite-oxidizing bacteria(0.35％),indicating that the activity of nitrite-oxidizing bacteria is significantly suppressed.Anammox bacteria are mainly enriched on the biofilm of the carriers in SNAD2.Overall,the two-stage SNAD-IFAS+O/A/O-MBR combined process is successfully started up.