Study On The Charicteristics Of Phenol Removal In The Coking Wastewater

In this study, extraction process had been used for removing phenol in highphenolic coking wastewater from Northern Shaanxi Hengyuan Coal Co. Ltd as apretreatment of wastewater. The influence factors of extraction are analyzed, and thefollow-up treatment was studied. On this basis, it provided the basic data for itsapplication in the treatment of coking wastewater that using immobilizedmicroorganism method to treat simulated phenolic wastewater. The results show that:（1） the volatile phenol concentration decreased from4165mg/L to127.62mg/L,and the volatile phenol removing rate reached more than96.94%,when thetemperature was lower than40℃, pH was less than8.0, the oil/water ratio R was1:2,the stirring time was8min, using30%TBP-kerosene solution as the extraction solvent.It created conditions to content with biological treatment. After the extraction solvent，TBP-kerosene，was washed by sodium hydroxide solution，the extraction solventrecycling rate is up to94.25%.（2） After the dephenolization pretreatment process, the chemical precipitationmethod was used to remove ammonia nitrogen from the waste water. The results showthat, when n （Na₂HPO₄·12H₂O）: n （NH₄⁺） is above0.8, the removal rate of ammonianitrogen can reach more than91.66%. The blowing ammonia method was used toremove ammonia nitrogen, and the removal rate can reach31.35%.（3）The waste water, after the dephenolization、ammonia removal、dilutionpretreatment process, is treated biochemical degradation、coagulation precipitation andactivated carbon adsorption process. The effluent COD, ammonia, phenol werereduced to0.49mg/L、16.25mg/L、84.92mg/L, the removal efficiencies were99.99%、 99.53%、99.73%. The effluent could meet the requirements of wastewater.（4） The immobilized microorganism method was used to treat simulated phenolicwastewater as the next step. The results show that: the efficient phenol degradingbacteria XA05was selected from the acclimated activated sludge. And when the initialphenol concentration was lower than957mg/L in the medium, the degradationefficiency of36h could be up to99.44%. The best immobilized method was PVAFreeze-thaw method, and the best immobilized conditions were: PVA concentration10%, the amount of bacteria4%. And in different temperature and pH, PVA biofilm onthe degradation of phenol rate was much higher than free of bacteria.