| The coal gasification wastewater with complicated composition includes toxic materials such as volatile phenol and cyanide. The toxicological effects are the main damage. The concentrations of COD, volatile phenol, ammonia nitrogen and cyanide in coal gasification wastewater are 12000～20000mg/L,2300～5000mg/L,500～800mg/Land 100～200mg/L respectively. At present the main treatment technology of coal gasification wastewater are primary and secondary treatment processes in China, while the quality of effluent cannot meet the discharge standard. Based on the components analysis in the coal gasification wastewater, solvent extraction technology, Fenton oxidization technology, screening and culture of high efficient bacteria and anaerobic ammonia oxidation technology have been all studied. The operation parameters and efficiency of the technologies were detected respectively by experiments, providing theoretical basis for the industrial application of coal gasification wastewater treatment. Besides, the results of experiments were applied to site operation in ceramics factory in Hengyang. The results showed that:1. The extraction conditions are:pH 3.0, temperature 30℃, extraction time 10min, extractant concentration 70%, extraction system phase ratio 3:1. The influent concentrations of COD, volatile phenol and ammonia nitrogen are 14000mg/L,3100mg/L and 650mg/L During extraction, the effluent concentrations of COD, volatile phenol and ammonia nitrogen decreased to 700mg/L,31mg/L and 540mg/L respectively, while the removal of cyanide was low. The extractant can be recycling used for 100 times at least.2. Secondary Fenton process can remove toxic materials in the extraction effluent, which is good for follow-up biochemical process. The optimal conditions have been obtained by orthogonal test and single factor test:pH 3.0, 1000mg/L of H2O2, 100mg/L of FeSO4, duration of experiment 10min. The pH of effluent is 3. The concentrations of COD, ammonia nitrogen are 210mg/L and 513mg/L. volatile phenol and cyanide cannot be detected in the effluent.3. The follow-up process of Fenton oxidation is anaerobic ammonia oxidation. The inoculants of is the. The experiment cultivated anaerobic ammonia bacteria in the UASB reactor for 145 hours, which is inoculated activate sludge from urban sewage treatment plant. After 40 days’operation, the concentration of COD and NH4+-N in effluent decreased to 40mg/L and 300mg/L respectively. The reaction conditions are:temperature 30℃, pH 7.8, HRT 24h.4.20 phenol degrading germs has been bred from sewage of aerobic facility of ceramics factory using the method of enrichment, separation, purification and screening. Maximum tolerable concentration of 5 germs can reach 2500 mg/L. one of the germ (SP1) whose maximum tolerable concentration reached 3000 mg/L was studied. The result showed that the degradation rate can reach 95.9% after 60h as the concentration of phenol was 2500mg/L and the most suitable conditions were 25℃, pH6.5, and 500 mg/L of glucose. DNA identification result turned out that SP1, whose similarity to known phenol degrading germs Klebsiella oxytoca strain is only 87%, belongs to Klebsiella sp and is a newly discovered kind. Double-chamber microbial fuel cell was constructed with the SP1 as catalyst. The effect of phenol degrading and productivity was studied with the high-phenol containing wastewater as fuel. The results showed that:After the microbial fuel cell running 100h, the removal rate of phenol and COD reached up to 85.5% and 90.4%, and the maximum output voltage is 121mV.5.The experiment results of extraction, Fenton oxidization, utilization of phenol degrading germs and biochemical treatment were applied to the site operation in a ceramics factory, choosing suitable process and parameters, have obtained good results and realized recycling and discharging up to standard. |
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