基于响应面法对一株好氧反硝化菌脱氮效能优化

Identification of a highly efficient aerobic denitrier and denitrification optimization using response surface method

摘要:

【目的】水体富营养化是当今我国水环境面临的重大水域环境问题，氮素超标排放是主要的引发因素之一。好氧反硝化菌构建同步硝化反硝化工艺比传统脱氮工艺优势更大。获得高效的好氧反硝化菌株并通过生长因子优化使脱氮效率达到最高。【方法】经过序批式生物反应器(Sequencing batch reactor，SBR)的定向驯化，筛选获得高效好氧反硝化菌株，采用响应面法优化好氧反硝化过程影响总氮去除效率的关键因子(碳氮、溶解氧、pH、温度)。【结果】从运行稳定的SBR反应器中定向筛选高效好氧反硝化菌株Pseudomonas T13，采用响应面法对碳氮比、pH和溶解氧关键因子综合优化获得在18 h内最高硝酸盐去除率95%，总氮去除率90%。该菌株的高效反硝化效果的适宜温度范围为25?30 °C；最适pH为中性偏碱；适宜的COD/NO3?-N为4:1以上；最佳溶解氧浓度在2.5 mg/L。【结论】从长期稳定运行的SBR反应器中筛选获得一株高效好氧反硝化菌Pseudomonas T13，硝酸盐还原酶比例占脱氮酶基因的30%以上，通过运行条件优化获得硝氮去除率达到90%以上，对强化废水脱氮工艺具有良好应用价值。

Abstract:

[Objective] The eutrophication of water body is one of pressing water environmental problems in China today. It is mainly caused by over-discharge of wastewater with high nitrogen. Aerobic denitrification bacteria are promising on simultaneous nitrification and denitrification process, presenting high advantages than conventional denitrification process. A high efficient aerobic denitrification strain was isolated and its nitrogen removal efficiency was optimized. [Methods] The aerobic denitrification strain was obtained in a SBR reactor, and response surface method was used to improve key factors influencing denitrification and total nitrogen removal efficiency. [Results] High efficiency aerobic denitrification strain of Pseudomonas T13 was selected from a SBR reactor. Based on response surface method, the highest nitrate removal rate was 95%, total nitrogen removal rate of 90% within 18 h, which were obtained by optimizing key factors of ratio of carbon and nitrogen, dissolved oxygen, pH, and temperature. The suitable temperature ranged from 25 °C to 30 °C. The optimal pH is neutral and the suitable COD/NO3?-N was over 4:1. The DO was around 2.5 mg/L. Pseudomonas T13 can use nitrate and nitrite as electron acceptor for nitrate respiration with 90% removal rate. [Conclusion] An aerobic strain with high efficient denitrification was identified as Pseudomonas T13 from a long-term running SBR reactor. Over 30% nitrate reductase were detected out of all denitrification enzyme genes from the strain. It is presenting a great potential on nitrate removal (>90%) to strengthen nitrogen removal process in wastewater treatment.