| In our country, the "energy rich coal, less oil, gas shortage" determines that a new generation of coal gasification industries plays a special role in the new clean and renewable energy transition in the next few decades. However, coal gasification wastewater was typically high concentrations of phenols, refractory organics and toxic pollutants. The treatment technologies of coal gasification wastewater from abroad and domestic usually had several problems, such as unsatisfactory effluents, poor stability and high handling costs. At present, after many years of research, through the use of multistage biochemical treatment process of coal gasification wastewater has yielded good results, but with the improvement of ecological environment protection requirement, the raise of cleaner production concept and the development of circular economy, the process has been can not meet the requirements of water reuse. So we need to continue to explore and innovate in developing new technology to meet the recycle standards with the coal gasification wastewater depth treatment.Through analysis of raw water and effluent by GC-MS, the results show that penetration rate of long chain alkane compounds is higher and its degradation rate is low, which contribute a lot to the effluent COD. Therefore, long-chain alkane pollutants were identified as target pollutants to depth processing in this subject.8strains of long chain alkane degrading bacteria were isolated from the secondary settling tank sediment of coal gasification wastewater treatment processes, and the degradation characteristics of hydrocarbon degrading bacteria were studied.4strains of these added to the MBBR system, the efficiency of simulated wastewater containing long chain alkanes and actual coal gasification wastewater were inspected, and the effects of HRT, dissolved oxygen and co-substrate to degradation. Further study was taken on hydrocarbon adsorption, uptake and degradation mechanism of hydrocarbon degrading bacteria, and the effect of various factors was investigated on the degradability of hydrocarbon degrading bacteria.It was found that long-chain alkane concentration increased will not cause serious damage to hydrocarbon degrading bacteria growth, and strain growth can be alleviated by extending training time. The effect of phenol compounds on long chain alkane degradation effectiveness to lys2-3than to lysl-3.150mg/L of naphthalene and10mg/L of cyanide both caused serious influence to lysl-3and lys2-3on the growth ability, so as to reduce hydrocarbon degradation ability. A certain concentration of yeast extract has no competitive inhibition on the substrate, and can promote the metabolism of degradation bacteria. But considering the practical engineering application, glucose and methanol are relatively easy and cheap to get, high cost performance. In addition, the study also examines the influence of simple carbon source on surface tension and cell surface hydrophobicity, and the influence of Interactions between the four strains on the degradability.Simulation tests show that MBBR bioaugmentation system on removal rate of COD and hydrocarbon content was obviously higher than that of control system. It was determined the suspended filler filling rate was30%, and the additive amount of exogenous bacteria accounted for15%dry weight ratio) of the total active sludge is better. Using of MBBR bioaugmentation system to deal with the actual coal gasification wastewater secondary sedimentation tank effluent, compared with M1reactor(control MBBR without long-chain alkane degrading bacteria), the dosing long-chain alkane degrading bacteria M2reactor(bioaugmentation MBBR with long-chain alkane degrading bacteria) can not only shorten the startup reaction time, but also effectively improve the long-chain alkanes and COD removal. Through the analysis of water quality, biomass and biological activity to see, M2in the long running process, and always maintained a high biomass and dehydrogenase activity. Compared with the M1, M2hydrocarbon removal increased significantly, indicating that adding long-chain alkane degrading bacteria play a biological role in strengthening and can long maintain its degradation activity in the reactor. At the same time, the trial found that HRT was8h, DO is3～5mg/L and dosing50mg/L of methanol do the best to the MBBR bioaugument sysment for the long-chain alkanes and COD removal. Therefore, it was good for MBBR bioaugument system to deal with coal gasification wastewater secondary sedimentation tank effluent by dosing long-chain alkanes degrading bacteria, significantly improved its long-chain alkane degradation rate, thus reduced the water content of COD. The effluent of M2water quality as the inflow of coagulating sedimentation tank, COD and biodegradable organic matter content decreased significantly dosage to reduce operating costs.The article discusses the long-chain alkane degrading bacteria degradation mechanisms. Carbon source area had a greater influence on the adsorption hydrocarbon compounds of2strains, but surfactant was slightly different effects on2strains. Two strains respectively were cultivated on eicosane and glucose as carbon source, which cells were observed to make use of transmission electron microscopy (SEM). It was found that the former cells had transparent inclusions, which was some difference in the morphology, but the latter had not been found inclusions in the cell. During2strains intake hydrocarbon, it need to consume energy, it is speculated that it may be to "eat" way to absorb alkanes. It was investigated the degradation mechanism of lysl-3living on n-hexadecane as substrate, and found that hydrocarbon degradation enzyme exists in intracellular. Through analysis intracellular and extracellular fatty acids by GC-MS, the results showed that palmitic acid is formed in fermented liquid, it is speculated that n-hexadecane metabolism may be by the monooxygenase. And the alkB functional gene obtained confirmed the speculation from the molecular level. In this paper, it was separated and identificated to8strains of long chain alkane degrading bacteria, deeply analysised on the adsorption, uptake and degradation mechanism, and proposed that long chain alkane compounds were deeply processing by adding the native hydrocarbon degrading bacteria in MBBR, which filled the blank in the research of long chain alkanes removal techniques in coal gasification wastewater at domestic and foreign... |
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