| Coking wastewater,as a characteristic organic wastewater,was mainly produced in the process of coke from coal,recovery and refining of coking products and gas purification.The concentration of COD was generally 4000-8000 mg/L.The research on effective treatment technology of coking wastewater has been the focus and hotspot at home and abroad.Anaerobic biological treatment technology has the characteristics of low energy consumption and biogas production,which was considered as one of the mainstream technologies for green and economical treatment of high concentration organic wastewater.However,the efficiency of anaerobic treatment of coking wastewater was not good,leading to the coking wastewater mainly depends on aerobic technology to degrade COD,while the aerobic treatment technology had the problem of high energy consumption,and the huge organic chemical energy contained in coking wastewater had not been effectively utilized.In order to realize the efficient and low-cost energy treatment of coking wastewater,this paper took coking wastewater as the treatment object,investigated the performance of anaerobic methanogenic system in the treatment of coking wastewater,analyzed the characteristics of anaerobic sludge and microbial population structure at different phases,and explores the inhibition mechanism.The inhibition factors of anaerobic methane production system in coking wastewater were studied by batch experiment.The main research conclusions are as follows: and mechanism(1)The performance of anaerobic methanogenic system was studied by means of gradient dilution of actual coking wastewater.The study found that only in the stage should be detectable VFA value,about 22 mg/L.VFA value below the detection limit when the COD value ? 1000 mg/L,but there was still a methane gas produced in the system,which may be because the generated VFA was used by methanogens of acetic acid type without surplus,and acidification phase has been inhibited.(2)Through the analysis of the characteristic components of the coking wastewater effluent,it was found that the removal efficiency of volatile phenols decreased from 95% to 20%,but the concentration of the removed volatile phenols remained at 90-100 mg/L,which may be related to the low hydrolysis acidification rate of volatile phenols.The concentration of ammonia nitrogen and sulfur compounds in effluent was higher than the influent value,which may be caused by the anaerobic decomposition of nitrogen compounds and sulfur compounds.The removal efficiency of thiocyanide was about 15% when the influent COD was 500 mg/L,but when the influent COD?1000 mg/L,the removal efficiency drops to 0.It may be that the residue of phenols inhibits the anaerobic degradation of thiocyanide.(3)The analysis of the microbial community structure at different phases shown that the abundance of Euryarchaeota in archaea remains above 99%,most of which were methanogens.Methanosaeta was the dominant genus of acetic acid nutritive methanobacteria,whose abundance was always greater than 46.81%.Methanobacterium and Methanolinea are dominant strains of hydrogen-trophic methanogens,with the abundance of 5.85%-9.63% and 3.24%-15.27%,respectively.The abundance of acetic acid nutritive methanogens was always greater than that of hydrogen nutritive methanogens,but the abundance of hydrogen producing bacteria(Firmicutes(8.11%-56.81%)was gradually greater than that of acid producing bacteria(Proteobacteria(7.41%-40.31%)),which may be caused by the failure of anaerobic methanogenesis in coking wastewater due to the mismatch of the abundance between functional microorganisms.(4)The main and secondary influencing factors of inhibiting anaerobic system were screened by orthogonal test,and the phenol > thiocyanide > ammonia nitrogen > sulfide was found,so phenol may be one of the key factors to inhibit the reaction of anaerobic methane production,and the influence of pollutants in coking wastewater on the anaerobic system had a synergistic effect. |
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