Studying On Bioaugmentation For The Degradation Of Coking Wastewater

Coking wastewater contain dozens of inorganic compounds and organic compounds: inorganic compounds are a large number of ammonium-salts, sulfur-cyanide, sulfide, cyanide, etc; in addition to phenols, organic compounds include single ring and multi-ring aromatic compounds, heterocyclic compounds which contains nitrogen, sulfur, oxygen. It is precisely because of coking wastewater containing these toxic substances, which harm and inhibit the activity of microorganisms, so conventional activated sludge treatment coking wastewater is difficult to meet national standards. The use of bioaugmentation, that is, culture some microorganisms which have strong ability to survive in polluted environment and degradate those pollutants, combination with different processing systems, then pollutants can be degraded effectively. Application of bioaugmentation to treatment coking wastewater is one of the most effective, safest, most thorough and most economical method.In this paper, through the cultivation of high effective microorganisms which can degrade coking wastewater, the individual characteristics, group identity and effect of O-A/O reactor of microorganisms were investigated. The complex microbial inoculants combination of cultured bacteria and mixed flora, which used degradation of coke plant wastewater, can be got from the following access.①screened more than 100 kinds of different bacteria from the coking plant activated sludge, according to their effect on the degradation of coking wastewater, of which 22 strains were selected as dominant bacteria;②collected rotten wood in nature, through the domestication and three white-rot fungi were selected ;③screened 16 strains from SBR reactor in the laboratory, which used degraded domestic sewage contained high concentrations of ammonia and phenol;④mixed culture coke plant activated sludge, and used different toxic substances to domesticated sludge, to improve their degradation efficiency;⑤a effective microorganisms inoculants preserved in laboratory. The microorganisms obtained from above ways, which was used for designing bioaugmentation regimen, had certain diversity.22 strains dominant bacteria were identified and their physiological characteristics were studied respectively, take strain 57 as an example: the results of 16S rDNA sequencing analysis is Pseudomonas sp; in the first 4h after inoculation, it is in the lag phase, the 4h to 88h in the logarithmic phase; the 88h to 132h in the stable phase, after 132h, went in the senescence phase; when the pH value is 7.5, it growth best; it is a facultative bacteria.Through assembling bacteria and studying complex microbial inoculants, It can be found the effect of the complex microbial inoculants was better than any single strain or their simple combination of these bacteria on the degradation of coking wastewater, and the inoculants contain more strains, the system more stably. The groupⅩis 20% higher than groupⅠof combination of aerobic bacteria, the groupⅤis nearly 20% higher than groupⅠof combination of facultative bacteria, the total complex microbial inoculants is more than 35% on COD degradation rate of coking wastewater.The degradation characteristics of complex microbial inoculants show that the effect of degradation of coking wastewater are closely related with the growth of microorganisms, it was observed that there was a positive correlation between COD removal rate and the mass of the microorganism in coking wastewater; the adapted pH range of flora was widely, when the pH value was 6, the rate of COD degradation was best; adding a certain amount of simple sugar into coking wastewater can promote the degradation effect of coke plant wastewater; adding acetic ammonia can effectively improve the degradation effect of COD; when the ration of the added nutrients and carbon and nitrogen is 3:1 to 5:1, had a good effect; coking wastewater lack of phosphorus element, added a certain amount of phosphorus element was very important to the degradation of coking wastewater; when added the concentration of Ca2+ was about 100mg /L, the microbial activity was better; when Fe2+ was more than 50mg /L, it would inhibit the growth of microorganisms; when Mg2+ was about 50mg /L, the biological activity was best; when the concentration of Mn2+ was about 50mg /L, the biological activity was best.The Application effect of complex microbial inoculants joint with O-A/O reactor was also studied. In the small-scale test, before adding complex microbial, the COD degradation rate of coking wastewater was about 40% the COD degradation rate was 56% after adding dominant bacteria, the COD degradation rate was 76% after adding complex microbial inoculants.The above results show that the complex microbial inoculants was used for treating coking wastewater is feasible. Combination complex microbial inoculants with specific reactor for treating coking wastewater, simplified the process, improved the treatment efficiency, reduced cost, and provided a theoretical basis and practical reference for bioaugmentation treatment the high concentration of refractory organic wastewater.