耐受高浓度氨氮异养硝化菌的筛选及其脱氮条件优化

研究了异养硝化菌对高浓度氨氮的耐受能力和去除能力.采用多点取样、高浓度氨氮废水强行驯化、驯化液连续梯度稀释、颜色指示剂快速硝化效果检测、平板划线分离等步骤,筛选能耐受高浓度氨氮废水的异养硝化菌株,以各菌株16S rDNA序列的系统发育分析来鉴定其种属,考察了菌株的脱氮特性,并通过提高C/N比和优化菌株配伍的方式对其脱氮能力进行了优化.结果共筛出8株高效的异养硝化菌株,并将其命名为N1～N8.系统发育分析表明8株菌分属丛毛单胞菌属（Comamonassp.）、红球菌属（Rhodococcus sp.）、假单胞菌属（Pseudomonas sp.）、节杆菌属（Arthrobacter sp.）、副球菌属（Paracoccus sp.）,其对起始氨氮浓度为256.9 mg.L-1、C/N=5.5的人工废水,72 h后氨氮去除率约在65%～80%之间,其中最高为N4的80.2%.若将上述废水的C/N比提高至8.0,则各菌株的氨氮去除率相应提高至约80%～90%.部分菌株配伍后脱氨氮效果优于任一单菌株,其中N4＋N5＋N6对起始浓度为261.1 mg.L-1的氨氮、在C/N=5.5的条件下,48 h去除率为88.2%.将N4＋N5＋N6组合驯化菌液,则能将该氨氮去除率提高至99.8%;在将起始氨氮浓度提高至446.9 mg.L-1、C/N比降为3.2后,52h后氨氮去除率亦可达99.9%,且最终几乎无亚硝酸盐氮和硝酸盐氮的积累,总氮去除率为66.5%,菌株同化的氮仅占损失氨氮的33%.可见驯化菌液中一些未能分离的菌株对分离出的菌株的脱氨氮效果有显著的协同作用.

Isolation of Heterotrophic Nitrifiers Which Can Tolerate High Concentration of Ammonia-nitrogen and the Optimization of Their Nitrogen Removal Efficiency in Wastewater

The removal capabilities and tolerance of high concentration of ammonia-nitrogen of heterotrophic nitrifiers were studied.Methods included multi-point sampling,domestication,gradient dilution of domestication liquid,color indicator as rapid nitrification detection and isolation from streaking plate were conducted to screen heterotrophic nitrifiers.The strains were identified according to the sequence analysis of 16S rDNA.After inoculating the strains into ammonia-nitrogen wastewater,changes of nitrogen compounds were measured in order to understand their denitrification characteristics.The denitrification efficiency was optimized by improving the C/N ratio,changing the compatibility of the strains and mixing the compatible strains with the domesticated bacterial suspension.Finally 8 high-efficiency heterotrohic nitrifiers were obtained,and named as N1-N8 respectively.Phylogenetic analysis showed that 8 strains belonged to Comamonas genus,Rhodococcusgenus,Pseudomonas genus,Arthrobacter genus and Paracoccus genus,respectively.When the initial concentration of ammonia nitrogen was 256.9 mg·L^-1 and the C/N was 5.5 of the artificial wastewater,the removal rates of ammonia nitrogen by the strains were about 65%-80%,and the stain N4 was the best.When the C/N ratio of the wastewater increased to 8.0,the ammonia nitrogen removal rates of the strains correspondingly increased to about 80%-90%.As the strains compatibility,the denitrification rate of N4+N5+N6 was 88.2% in the artificial wastewater with initial ammonia nitrogen concentration was 261.1 mg·L^-1 and initial C/N ratio was 5.5, which was higher than that of any single strain.The ammonia nitrogen removal rate could reach to 99.8% when N4+N5+N6 were combined with the domesticated bacterial suspension.In the artificial wastewater,when the initial ammonia nitrogen increased to 446.9 mg·L^-1 and the C/N ratio decreased to 3.2,the ammonia nitrogen removal rate of the mixed strains which composed of N4+N5+N6 and domesticated bacterial suspension was 99.9%.There was almost no nitrite and nitrate nitrogen accumulated in eventually,and the total nitrogen removal rate was 66.5%.The nitrogen which was assimilated by the strains was only 33% of the lost ammonia nitrogen.It shows that the strains which could not be isolated in the domesticated bacterial suspension had significant synergies effects on ammonia nitrogen removal of the isolating strains.