耐高浓度氨氮的异养硝化好氧反硝化菌株U1的鉴定及其脱氮特性

Identification and denitrification characteristics of heterotrophic nitrification and aerobic denitrification strain U1 resistant to high concentrations of ammonia nitrogen

摘要:

【背景】城市垃圾渗滤液是一种成分复杂的有机废水，含氮量高，如果未经处理直接排放到环境中会造成严重的环境污染。【目的】筛选可以耐受垃圾渗滤液中高浓度氨氮并高效去除污水中氮素的异养硝化好氧反硝化菌株，为解决垃圾渗滤液的氮素污染提供功能菌株。【方法】从垃圾渗滤液中筛选分离能耐受高氨氮浓度的菌株，通过测定各菌株的脱氮能力，筛选到一株脱氮能力最强的菌株，命名为U1，通过测定16S rRNA基因序列和生理生化特性确定该菌株为铜绿假单胞菌。进一步研究了菌株U1在不同初始氨氮浓度、碳源、转速、初始pH、碳氮比等单因素变量下的脱氮能力，并结合L₉(3⁴)正交试验研究了菌株U1的最佳脱氮条件。【结果】分离出一株铜绿假单胞菌并命名为U1。该菌株的最优脱氮条件为：初始氨氮浓度为1 000 mg/L，红糖和柠檬酸三钠的混合碳源，pH 6.0，C/N为10，转速为130 r/min，菌株U1的最大总氮去除率为64.37%，最大氨氮去除率为76.73%。对于总氮和氨氮含量分别是2 345 mg/L和1 473.8 mg/L的垃圾渗滤液，菌株U1最大总氮去除率为27.86%，最大氨氮去除率为21.32%。【结论】菌株U1可以用于处理垃圾渗滤液等高浓度氨氮废水。

Abstract:

[Background] Municipal waste leachate is a kind of complex organic wastewater with high nitrogen content, which can causes serious environmental pollution if discharged directly into the environment. [Objective] To select heterotrophic nitrifying and aerobic denitrifying (HN-AD) strains that can tolerate high concentration of ammonia nitrogen in waste leachate and efficiently remove nitrogen from wastewater, and thereby provide functional strains to address nitrogen pollution in urban wastewater. [Methods] The strains that could tolerate high concentration of ammonia nitrogen were isolated from the waste leachate, and a strain with the strongest denitrification capacity was screened out and named U1. Based on 16S rRNA gene sequencing and physiological and biochemical characteristics, U1 was identified as Pseudomonas aeruginosa. Then we further investigated nitrogen removal ability of U1 in the presence of ammonia nitrogen of different initial concentration and different carbon sources, and at different rotation speeds, initial pH, and carbon-to-nitrogen ratios, and explored the optimal nitrogen removal conditions of U1 in combination with L₉(3⁴) orthogonal test. [Results] U1 with strong denitrification ability was isolated and the optimum denitrification conditions for this strain are as follows: ammonia nitrogen at initial concentration of 1 000 mg/L, mixed carbon source of brown sugar+ trisodium citrate, pH of 6.0, carbon-to-nitrogen ratio of 10, and rotation speed of 130 r/min. Under the optimum conditions, the maximum total nitrogen removal rate of U1 was 64.37% and the maximum ammonia nitrogen removal rate was 76.73%. For the waste leachate with total nitrogen and ammonia nitrogen amount of 2 345 mg/L and 1 473.8 mg/L, respectively, the maximum removal rate of total nitrogen by U1 was 27.86% and the maximum removal rate of ammonia nitrogen was 21.32%. [Conclusion] U1 can be used to treat wastewater with high-concentration ammonia nitrogen.