水体中反硝化细菌的分离、筛选与初步鉴定

水体中反硝化细菌的分离、筛选与初步鉴定 邵基伦 环境工程专业

摘要：当今世界环境污染日益加重，尤其是水体污染已严重影响人们的日常生活与身体健

康。水污染是多方面的因素综合作用，而以氨氮的污染最为广泛且严重。所以控制污水中的氨氮含量是污水处理中的重要内容。污水脱氮的基本原理是污水中的含氮有机物首先经过微生物的氨化作用转化为氨，硝化细菌的硝化作用，将氨氧化为亚硝酸盐，并继续氧化为硝酸盐。硝酸盐经过反硝化细菌的反硝化作用转化为氮气等环节成分而释放到大气中，从而实现污水脱氮。硝化作用是这一过程中的一个中间环节，也是一个重要环节。硝化作用是指氨经过微生物的作用氧化为亚硝酸和硝酸的过程，由硝化细菌完成。硝化细菌是一类好样化能自养细菌，包括亚硝化细菌和硝化细菌两个亚群。硝化细菌能够利用还原态无机氮化合物进行自养生长，硝化细菌的生命活动在污水脱氮中起重要作用。由于硝化细菌是化能自养菌，其生长速率很慢，因此硝化、亚硝化细菌的生命活动成为污水脱氮的关键步骤之一。它们能有效降低水体中氨氮及亚硝酸氮的含量，对水产养殖业及环境保护具有重要意义。硝化细菌是生物硝化脱氨中起主要作用的微生物，直接影响硝化效果和生物脱氨的效率。因为硝化细菌、亚硝化细菌在污水脱氮中的特殊意义，对这类微生物的研究受到广泛关注。 氨和亚硝酸分别是亚硝化菌和硝化菌的唯一能源。对于硝化细菌来说生长环境中的温度对其影响较大，pH值和盐度的影响相对较小。大多数硝化细菌的合适生长温度为10～38 ℃，高于20℃时硝化细菌的活性较高，但超过38℃消化作用将会消失。当环境气温低于 20℃时，氨的转化会受到影响。一般认为，适宜硝化菌和亚硝化菌生长介质的pH值分别为6.0～8.5和6.0～8.0。水体DO的高低影响到好氧、厌氧微生物的比例，大多数研究人员认为DO的浓度应当控制在1.0～2.0 mg/L,低于0.5 mg/L时硝化作用明显减弱。另外,碳氮比、碱度等对硝化及脱氨均有影响。 本实验采用人工培养基方法富集培养硝化细菌．研究了富集培养过程中硝化与亚硝化细菌的结构和性质变化。结果表明，在25-28℃，pH7．5～8.5，D0 2-5mg／L，氨氮浓度100—150mg／L条件下，经过19d和15d的富集培养，可以得到硝化速率为4.18mg(NH3-N)-[g(MLSS)/h]和10.1mg(NH4-N)-[g(MLSS)/h]的硝化细菌培养物．在这种富集培养过程中，硝化细菌培养物的污泥色泽和结构、MLSS、SV30、SVI、硝化强度和硝化速率等均出现规律性变化且随培养方法不同表现出明显差异。 关键词：硝化细菌；反硝化细菌；脱氮；富集培养；硝化速率；活性污泥；载体

Abstract: In today's world environment pollution is aggravating, especially the water pollution

has seriously affect People's Daily life and health. Water pollution is various factors, and ammonia nitrogen pollution in the most extensive and severe. So control of ammonia nitrogen content is sewage wastewater treatment in the important content. The basic principle of sewage denitrification is the nitrogen organic wastewater by microbes function first ammoniation into ammonia, nitrifying bacteria of nitrification, will ammonia oxidation as nitrite, and continue to oxidation as nitrate. Nitrate after denitrifying bacteria against nitrification into nitrogen links such as composition and released to the atmosphere, so as to realize the sewage denitrification. Is this a nitrification process of a intermediate link, and also an important link. Nitrification refers to the role of ammonia after microbial oxidation and the process of nitric acid based, by nitrifying bacteria complete. Nitrifying bacteria is a kind of photosynthetic bacteria can fleas, including the nitrifying bacteria and nitrifying bacteria two subsets. Nitrifying bacteria can use YuanTai inorganic nitrogen compounds are also growing autotrophic, nitrifying bacteria in the life activities of sewage denitrification plays an important role. Because of nitrifying bacteria is which can sustain bacterium, the growth rate is slow, therefore nitrification, nitrosation bacteria life activities of sewage denitrification become one of the key steps. They can effectively reduce the water in ammonia nitrogen based and nitrogen content, aquaculture and environmental protection to have the important meaning. dressfying bacteria is biological nitration take off to play a major role ammonia of microbes, directly influence the effect and biological nitrification off the efficiency of ammonia. Because nitrifying bacteria, denitrifying bacteria in the sewage and denitrification of special significance, for this kind of microbe study is widely concerned about.

Ammonia and respectively based nitrosation bacteria and is the only energy denitrifying bacteria. The essential bacteria growth environment for it to its large effect on the temperature, pH value and salinity influence is relatively minor. The most essential bacteria growth temperature right for 10 to 38 ℃, 20 ℃ higher than when the activity of nitrifying bacteria are higher, but more than 38 ℃ digestive function will disappear. When the environment temperature less than 20 ℃, ammonia transformation can be affected. Generally, appropriate denitrifying bacteria and the denitrifying bacteria growth medium pH value were 6.0 ~ 8.5 and 6.0 ~ 8.0. The water DO will affect the good oxygen, anaerobic microbe proportion, most researchers think the concentration shall control in DO 1.0 ~ 2.0 mg/L, less than 0.5 mg/L nitrification when significantly weakened. In addition, carbon and nitrogen, basicity on than nitrification and take off all affect the ammonia.

This experiment used artificial medium enrichment of nitrifying bacteria cultivation method. The process of cultivation of nitration and enrichment of nitrifying bacteria and the structure and properties of change. The results show that, in 25 to 28 ℃, pH7.5 ~ 8.5, D0 2-5 mg/L, ammonia nitrogen's 100-150 mg/L conditions, after 19 d and 15 d enrichment training, can get nitration rate for 4.18 mg (NH3-N)-[g (MLSS) / h] and 10.1 mg (NH4-N)-[g (MLSS) / h] of nitrifying bacteria culture substance. In this enrichment process of cultivation, nitrifying bacteria culture substance of sludge colour and lustre and structure, MLSS, SV30, SVI, nitrification strength and nitration rate all appear to regular change with different methods and training showed obvious difference.