低温异养硝化-好氧反硝化菌株筛选及在循环养殖系统的应用OA

To investigate the nitrogen removal efficiency of a cold-water fish recirculating aquaculture system(RAS)inoculated with a low-temperature nitrogen-removing bacterium under low-temperature conditions,a laboratory RAS was constructed based on a moving bed biofilm reactor in this study.A novel low-temperature heterotrophic nitrification-aerobic denitrification bacterium,Glutamicibacter sp.YTLJ-N-S7 was isolated and subsequently inoculated into the biological reactor of the Oncorhynchus mykiss RAS.The nitrogen removal performance in the practical system was evaluated by monitoring the concentrations of NH4+-N,NO3--N,NO2--N and TN.The results showed that during operation of the treatment system,the effluent concentrations of NH4+-N,NO3--N and NO2--N were maintained within the ranges of 0.50-0.90 mg/L,2.11-4.26 mg/L,and 0.03-0.07 mg/L,respectively,while the effluent TN concentration remained below 5.01 mg/L.Compared to the control group,the average removal efficiencies of NH4+-N,NO3--N,NO2--N and TN in the treatment group increased by 26.89％,49.50％,41.88％and 46.90％,respectively.This confirms the strong nitrogen removal potential of this low-temperature heterotrophic nitrification-aerobic denitrification bacterium in cold-water fish RAS.Furthermore,single-factor experiments were conducted to examine the effects of different environmental factors on the heterotrophic nitrification-aerobic denitrification performance of this strain.The suitable salinity and pH ranges for strain YTLJ-N-S7 were determined to be 0‰～30‰ and 6～9,respectively.Under low-temperature conditions at 15 ℃,with either 100 mg/L NH4+-N or 120 mg/L NO3--N as the sole nitrogen source,the maximum nitrification and denitrification rates reached 3.52 mg N/(L·h)and 3.40 mg N/(L·h),respectively.The highest removal efficiencies achieved were 96.29％±0.04％for nitrification and 100％±0.00％for denitrification.These findings provide valuable references for the practical application of this strain.Good denitrification results were obtained in cold-water fish RAS during a 28 day operation.