有机碳源对微生物代谢所致水体黑臭现象形成的影响机制

Influence and Mechanism of Organic Carbon Source on Formation of Black and Odorous Water Body Caused by Microbial Metabolism

黑臭水体已成为最亟需解决的城市水环境问题。有机污染是导致水体黑臭的关键因素,但有机碳源对黑臭现象形成的影响机制尚不明晰。文中以淀粉为有机碳源、实际黑臭水样为菌液,在封闭静态微生态系统中模拟水样黑臭现象形成过程。试验结果表明,水样黑臭现象形成受微生物驱动,适宜的菌液比为1∶250,在该菌液比下有机碳源[淀粉,以总有机碳(TOC)计]质量浓度≥100 mg/L时,水样出现黑臭现象。皮尔逊相关性分析表明水样黑臭程度(色度和臭阈值)与有机碳源浓度显著正相关,而溶解氧(DO)与有机碳源浓度极显著负相关(p<0.01,r^(2)=0.98),说明有机碳源是水体黑臭的重要因素。通过测定水样中DO、Fe^(2+)、S^(2-)和FeS浓度变化,表明试验条件下有机碳源对水样黑臭现象形成的影响机制是微生物分解有机碳源消耗水中大量DO,导致水样在缺氧还原状态下易产生FeS和H_(2)S等致黑、致臭物质。

Contamination caused by black and odorous water body of urban water environment is urgent to be controlled.Organic pollution is the key cause of black and odorous water body,however the influence and mechanism of organic carbon source on the formation of black and odorous water body are still not very clear.In this paper,a simulation in closed static micro-ecosystem,in which organic carbon and bacteria liquid was starch and sample of actual black and odorous water respectively,had been done to investigate the forming process of black and odorous water body.Results showed that the microorganism was a driven factor of the process and the suitable ratio of bacteria to liquid was 1∶250,with the sample of water became black and odor when organic carbon source[starch,calculated as total organic carbon(TOC)]concentration was greater than or equal to 100 mg/L.Pearson correlation analysis proved that black and odorous level(chroma and odor threshold)of the tested water samples had significant positive correlation with the concentration of organic carbon sources, while dissolved oxygen (DO) had very significant negative correlation with the concentration of organic carbon sources (p<0. 01, r^(2) =0. 98), it indicated that organic carbon source was a key factor of the forming process of black and odor. By measuring the change in the concentration of DO, Fe^(2+) , S^(2-) and FeS, the mechanism of organic carbon sources on the formation of black and odorous in water samples could be summarized. Under this test condition the microorganism decomposed the organic carbon sources and consumed a large amount of DO. Under such anoxic and reduction condition, the water produce much black and odorous substance such as FeS and H_(2)S that results in black and odorours phenomena.