风化壳淋积型稀土矿闭矿场土著菌株的筛选及其脱氮性能

Screening and Nitrogen Removal Properties of Native Strains Isolated from the Weathered Crust Elution Deposited Rare Earth Tailings

针对风化壳淋积型稀土矿闭矿场内浸矿剂缓释所造成的氨氮长期超标问题,从矿区周围筛选得到2株具有异养硝化-好氧反硝化能力的土著脱氮菌A12和TXF8,并探讨其脱氮特性。研究结果表明,A12和TXF8菌株经鉴定为克雷伯菌(Klebsiella oxytoca)和噬碱假单胞杆菌(Pseudomonas alcaliphila),呈均一杆状结构,平均长度分别为1.0μm和1.6μm;经优化,在选用柠檬酸钠为碳源,C/N=10.0,初始pH=7.0~8.0的条件下,氨氮去除率达到96.0%以上,TXF8较A12菌株具有更强的氨氮耐受性及较大的氨氮去除速率,最大氨氮耐受浓度可达600 mg/L;在硝化阶段,细菌将氨氮部分氧化为硝态氮,继而进行反硝化脱氮,脱氮全程无亚硝态氮的有效积累,经14.0 h降解,A12和TXF8菌株的总氮去除率分别为64.83%和75.09%,出水氨氮浓度分别为2.13 mg/L和3.45 mg/L,达到我国排放标准。研究结果为风化壳淋积型稀土矿氨氮污染的生物脱除提供一定理论依据与技术支撑。

To solve ammonia nitrogen pollution around the weathered crust elution deposited rare earth tailings caused by slow release of leaching agent, two native strains named A12 and TXF8 with heterotrophic nitrification and aerobic denitrification ability were isolated from the surrounding area of the tailings.The ammonia nitrogen removal properties were investigated.The results showed that A12 and TXF8 were identified as Klebsiella oxytoca and Pseudomonas alcaliphila with uniform rod structure, and the average length of A12 and TXF8 were 1.0 μm and 1.6 μm, respectively.After optimization, ammonia nitrogen removal efficiency reached more than 96.0% under the conditions of sodium citrate as carbon resource, C/N=10.0,initial pH=7.0-8.0.Furthermore, TXF8 showed better tolerance and higher ammonia nitrogen removal rate than A12 in high ammonia nitrogen concentration.The maximum tolerance concentration of ammonia nitrogen could be reached as 600 mg/L.In the nitrification process, ammonia nitrogen was partially oxidized to nitrate nitrogen followed by denitrification.No effective accumulation of nitrite nitrogen was found in the whole process.After 14.0 h degradation, the total nitrogen removal efficiencies of A12 and TXF8 were 64.83% and 75.09%,respectively.The effluent ammonia nitrogen concentration was 2.13 mg/L and 3.45 mg/L,which reached the national emission standard.The research results provide theoretical basis and technical support for the biological removal of ammonia nitrogen released from weathered elution deposited rare earth tailings.