| Some organic pollutants such us alkyl phenols,polycyclic aromatic hydrocarbons,amines and halogen compounds are still in the effluent of coking wastewater by biological treatment.Most of these pollutants have"carcinogenic,teratogenic,mutagenic"effect and toxicity,there may ecological security and human health risks.In addition,the higher color and COD of the coking wastewater effluent can not meet the Emission Standard of Pollutants for Coking Chemical Industry?GB16171-2012?.So looking for a new method is necessary for advanced treatment of coking wastewaterAdvanced treatment of coking wastewater were investigated by Fe2+,UV activated persulfate oxidation,the results are as follows:?1?The effect of S2O82-concentration,Fe2+concentration,initial pH value,temperature,concentration of EDTA and time on Fe2+activated persulfate oxidation were studied with the effluent of coking wastewater by A2/O process,which was from coking plant in changzhi city,Shanxi Province.Optimum operating condition are:no pH control,K2S2O8concentration of 3.5 mmol/L,FeSO4·7H2O concentration of 7 mmol/L,controlled temperature of 30?,EDTA concentration of 0.02 mmol/L,time of 120 min.Under these conditions,the the chroma removal rate was 95.19%,UV254 removal rate is 61.18%;TOC decreased from 52.88mg/L to 52.88 mg/L,TOC removal rate reached 53.45%,The effluent quality could meet the Emission Standard of Pollutants for Coking Chemical Industry?GB16171-2012?.?2?Some factors of effecting UV activiated persulfate oxidation were studied with the effluent of coking wastewater from coking plant in yuci city,Shanxi Province by A2/O and coagulation process,which included S2O82-concentration,initial pH value,temperature,light intensity and time.Optimum operating conditions are:the pH of 3,K2S2O8concentration of 3.5mmol/L,light intensity of 9.94 mw/cm2,temperature of 30?,time of 120 min.The effluent concentration of TOC is 18 mg/L,and the TOC removal rate reached 71.5%.the chroma removal rate was more than 99%;UV254 removal rate reached 92.6%.Effluent quality could meet the Emission Standard of Pollutants for Coking Chemical Industry?GB16171-2012?.?3?The effects of Cl-concentration on UV activated persulfate oxidation of coking wastewater was studied.the results showed that the removal rate of chroma declines with Cl-concentration increasing under the pH of 3,S2O82-concentration of 3.5 mmol/L,temperature of 30?,light intensity of 9.94 mw/cm2,time of 120 min.The removal of UV254and TOC can be promoted while Cl-concentration is in the range of28.2-29.1 mmol/L,and be inhibited in Cl-concentration of 38.1mmol/L.?4?By comparision of two advanced treatmengt methods of Fe2+and UV activated persulfate oxidation of coking wastewater,the results showed that the removal rate of chroma,UV254,TOC and COD was85.81%,96.4%,53.64%and 41.53%respectively in Fe2+activated persulfate oxidation of coking wastewater of 120 min treatment.The removal rate of Chroma,UV254,TOC and COD removal rate were97.94%,81.99%,47.13%and 37.44%respectively in UV activated persulfate oxidation of coking wastewater of 120 min treatment.The removal rate of TOC and COD in Fe2+activated persulfate oxidation are superior to that of TOC and COD in UV activated persulfate oxidation,and the removal rate of the chroma and UV25454 in UV activated persulfate oxidation are better than that of the chroma and UV254 in Fe2+activated persulfate oxidation?5?By economic comparision of the advanced treatment of Fe2+and UV activated persulfate oxidation of coking wastewater,the results showed that the cost of Fe2+activated persulfate oxidation of coking wastewater is 6.1891 yuan per ton,and the cost of UV activated–persulfate oxidation is 6.426 yuan per ton.Advanced treatment of Fe2+activated persulfate oxidation of coking wastewater will be recommended. |
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