The Screening And Degradation Characteristics Study On Predominant Bacterias To Hard-biodegradable Organics In Coking Wastewater

Coke-plant wastewater is complicated. It contains phenol, cyanide, high concentration of ammonia and a variety of refractory organics, such as aromatic, heterocyclic and polycyclic compounds. Pyridine, quinoline, naphthalene and phenol are typical refractory organics of coking wastewater. Because of theirs toxicity, teratogenic, carcinogenic and hard-biodegradable characteristics, it results in poor degradation and high COD concentration. And it is hard to meet emission standards after the traditional biological treatment, which still bring potential hazards to environment and human health. For coking wastewater hard-biodegradable organic matters, an effective and economic treating methods must be studied. Adding high-effective bacterium selected from the natural environment can strengthen the biological treatment, and increase the capacity of refractory organic removal. Environmental workers are recently interested in it,and it has become a research hotspot.For typical biodegradable organic compounds of coking wastewater (pyridine, quinoline, phenol, naphthalene), four strains were isolated of activated sludge from WISCO coking plant wastewater, they could grow using pyridine, quinoline, phenol, naphthalene as only carbon and nitrogen source,labeled Y-P, Y-Q, Y-PH and Y-N. The study researched predominant bacteria of the degradation characteristics, and investigated the effect of initial concentration, bacteria adding percentage, pH, temperature and different metal ions on degradation characteristics; the effect of different combinations among strains on degradation rate of pyridine, quinoline, phenol and naphthalene was studied, and the optimal combination was used in coking wastewater treatment under laboratory conditions.The results showed predominant bacteria were in better tolerance of target pollutants, such as Y-PH up to 1800mg/L. The dominant bacteria identified by morphologic observation and physiology biochemistry experiment were that Y-P was Micrococcaceae, Y-Q was Bacillaceae, Y-PH was Arthrobacter and Y-N was Pseudomonadaceae. The optimal temperature of all four strains is 30℃. The optimal pH value of predominant bacteria Y-Q was 8.5, and optimal pH value of other bacteria was 7.5. An amount of Fe2+ could increase the degradation rate of bacterium Y-P and Y-N, and an amount of Zn2+ could increase the degradation rate of bacterium Y-Q and Y- PH. The optimal bacteria adding percentage of Y-P, Y-Q, Y-PH, Y-N was 5%,8%,6% and 4%. The 2:1:4:4 ratio of combination of Y-P, Y-Q, Y-PH and Y-N was the best advantage of complex combination of bacteria. After using the predominant bacterium combination and the activated sludge together, concentrations of COD and NH3-N both achieved country first-level emission standard.The results of this study provide a technical basis for difficult degradable organic ,and provide a reference for further research and application.