Characteristics of a heat-resistant Nitrosomonas enrichment culture and its ammonia-removing ability in various waste waters
XU Hui， GAO Huijuan， CAI Yuheng， SU Kexing， LIU Haojie， CHENG Kai
Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization/College of Resources and Environmental Engineering， Hubei University of Technology， Wuhan 430068， China
Abstract：An enrichment culture of autotrophic ammonia oxidizing bacteria was isolated from domestic wastewater. The only one strain of autotrophic ammonia oxidizing bacteria in the enrichment culture was named as Nitrosomonas nitrosa SN-6 because its 16s rDNA sequence and amoA gene sequence was highly similar to N. nitrosa Nm90 at an identity of 100%. The influences of high temperature on the activity and growth of N. nitrosa SN-6 were studied both in medium and in landfill leachate. The influences of free nitrous acid and salinity on its ammonia removing ability were studied. Also， the ammonia-removing ability was measured in polluted ground water. The results showed that the highest tolerance temperature of the enrichment culture was no less than 43 ℃，and the maximum NO-N accumulation rate reached 129 mg·L－1·d－1. Moreover，the optimum growth temperature was 37-40 ℃ in medium (with the doubling time of 6.1 h)， and was 40 ℃ in landfill leachate (with the doubling time of 5.9 h). The IC50 of deammoniation by salinity was a little more than 1%，and the IC50 of deammoniation by free nitrous acid was about 0.095 mg·L－1. Moreover， in polluted ground water， the initial NH3-N decreased from 5-23 mg·L－1 to less than 1.5 mg·L－1 in 3 days. The above results demonstrated that SN-6 was not only suitable for high NH3-N concentration at high temperature， but also suitable for low NH3-N concentration at normal temperature， which suggests a great advantage in application.
2021, Vol. 55 
