Achieving robust nitritation in a modified continuous-flow reactor: From micro-granule cultivation to nitrite-oxidizing bacteria elimination  

作　　者：Wenru Liu Jiajun Song Jianfang Wang Xiaoming Ji Yaoliang Shen Dianhai Yang 

机构地区：[1]National&Local Joint Engineering Laboratory for Municipal Sewage Resource Utilization Technology,Suzhou University of Science and Technology,Suzhou 215009,China [2]School of Environmental Science and Engineering,Suzhou University of Science and Technology,Suzhou 215009,China [3]College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China [4]State Key Laboratory of Pollution Control and Resources Reuse,Tongji University,Shanghai 200092,China

出　　处：《Journal of Environmental Sciences》2023年第2期117-129,共13页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos. 51808367 and 51878430)

摘　　要：In this study,a modified continuous-flow nitrifying reactor was successfully operated for rapid cultivation of micro-granules and achieving robust nitritation.Results showed that sludge granulation with mean size of ca.100μm was achieved within three weeks by gradually increasing settling velocity-based selection pressure from 0.48 to 0.9 m/hr.Though Nitrospira like nitrite-oxidizing bacteria(NOB)were enriched in the micro-granules with a ratio between ammonia-oxidizing bacteria(AOB)and NOB of 5.7%/6.5% on day 21,fast nitritation was achieved within one-week by gradually increasing of influent ammonium concentration(from 50 to 200 mg/L).Maintaining ammonium in-excess was the key for repressing NOB in the micro-granules.Interestingly,when the influent ammonium concentration switched back to 50 mg/L still with the residual ammonium of 15–25 mg/L,the nitrite accumulation efficiency increased from 90%to 98%.Experimental results suggested that the NOB repression was intensified by both oxygen and nitrite unavailability in the inner layers of micro-granules.Unexpectedly,continuous operation with ammonium in excess resulted in overproduction of extracellular polysaccharides and overgrowth of some bacteria(e.g.,Nitrosomonas,Arenimonas,and Flavobacterium),which deteriorated the micro-granule stability and drove the micro-granules aggregation into larger ones with irregular morphology.However,efficient nitritation was stably maintained with extremely high ammonium oxidation potential(>50 mg/g VSS/hr)and nearly complete washout of NOB was obtained.This suggested that smooth and spherical granule was not a prerequisite for achieving NOB wash-out and maintaining effective nitritation in the granular reactor.Overall,the microgranules exhibited a great practical potential for high-rate nitritation.

关 键 词：Continuous flow GRANULATION NITRITATION Nitrate-oxidizing bacteria REPRESSION 

分 类 号：X703[环境科学与工程—环境工程]