Study on nitrogen and phosphorus removal in SPNPR-A system based on short-cycle regulation
In this study,a simultaneous partial nitrification and phosphorus removal-anaerobic ammonia oxidation(SPNPR-A)system with short-cycle and low-concentration nitrite(NO2-N)was established.The SPNPR system operates in anaerobic/aerobic mode,and the NO2--N concentration in the system was limited for a brief duration to restrict nitrite oxidizing bacteria(NOB),simultaneously enriching ammonia oxidizing bacteria(AOB)and polyphosphate accumulating organisms(PAOs),and finally realizing synchronous nitrogen and phosphorus removal.The results showed that the NOB activity could be effectively inhibited by maintaining the NO2--N concentration in the SPNPR system at about 10mg/L for a short-cycle.After 70days,the nitrite accumulation rate(NAR)of the two short-cycles of SPNPR system reached 90.40％and 88.93％,respectively,and the average removal rates of total nitrogen(TN),total phosphorus(TP)and chemical oxygen demand(COD)in SPNPR-A system were 87.45％,84.30％and 94.26％,respectively.At the 60th day,specific ammonia oxidation rate(SAOR)and specific oxygen utilization rateAOB(SOURAOB)were 8.47mgN/(gMLVSS·h)and 12.71mgO2/(gMLVSS·h),respectively.Specific nitrate production rate(SNPR)and specific oxygen utilization rateNoB(SOURNOB)were 0.82mgN/(gMLVSS·h)and 0.41mgO2/(gMLVSS·h),respectively.The results of high-throughput sequencing showed that,the abundance of AOB genera Nitrosomonas(6.46％)and Nitrosospira(0.64％)in SPNPR system was much higher than that of NOB genera Nitrospira(0.14％)and Nitrobacter(0.01％)on the 70th day,and at the same time,the phosphate accumulating organisms of Candidatus_Accumulibacter(1.61％)and Tetrasphaera(0.89％)were gradually enriched,so that the SPNPR-A system underscored the robust performance of synchronous nitrogen and phosphorus removal.
short-cyclelow concentration nitritepartial nitrificationnitrogen and phosphorus removal
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