Field Tests On Removal Effect Of Volatile Phenolic Compounds From Semi-coking Wastewater

The removing of phenolic compounds from the semi-coking wastewater by usingthe integrated process of “extraction–biodegradation–coagulation and sedimentation–activated carbon adsorption” were investigated and field tests were taken in this study.Optimal conditions of each processing stage were explored through field tests, whichprovided references for semi-coking wastewater treatment applications. The resultsshowed that:(1) The removal rate of volatile phenol was80%by using30%concentration ofTributyl phosphate(TBP)-kerosene as extractant under normal temperature when the pHwas within the range of3to9, the extraction time was20mins, the volume ratio ofextraction was1:7, and the recovery rate of volatile phenol from extractant could bereached to80%by taking alkali solution recovery method. And the removal rate ofvolatile phenol was90%by using methyl isobutyl ketone(MIK) as extractant undernormal temperature when the pH was within the range of3to9, the extraction time was10mins, the volume ratio of extraction was1:7, and the recovery rate of volatile phenolfrom extractant could be reached to95%by taking distillation recovery method. Thecomparison indicated that the extraction effect on volatile phenolic compounds of MIKwas better than that of TBP.(2) The degradation removal ratio of volatile phenol could be reached about80%and the volatile phenol could be reduced from above600mg/L to about100mg/L whenthe pH of water ingress was7to8, and the aeration time was12hours by takingactivated sludge which was acclimated to biodegrade pretreated wastewater. Theadsorption removal ratio of volatile phenol could be reached about75%and the volatile phenol could be reduced from above600mg/L to about150mg/L when the MLSS ofwastewater was5g/L, and the aeration adsorption time was8hours by takingbio-flocculate to adsorb pretreated wastewater in winter cold condition.(3) The coagulation effect of Polymeric Ferric Sulfate(PFS) was better than PolyAluminum chloride(PAC) by taking treatment of coagulation and sedimentation forbiochemistry effluent and by adding optimum dosage of both PFS and PAC underlaboratory condition. For the best effect of coagulation and sedimentation, the removalrate of volatile phenol could be reached above60%and the concentration of volatilephenols precipitation effluent could be reduced to50mg/L or so when the pH of wateringress maintained between7and8, the dose of PFS was1.0-1.5g/L, the dose ofsemi-coking carbon as coagulant aid was1g/L, and the settling time was30mins.(4) the adsorption removal ratio of volatile phenol could be reached about95%andthe concentration of volatile phenol could be reduced from about50mg/L to below3mg/L when the pH of water ingress was7, and the adsorption time was15mins bytaking advanced treatment of granular active carbon for precipitation effluent. Acomparison on adsorption effect between modified semi-coking carbon and granularactive carbon was taken to reduce treatment cost. The results indicated that theadsorption capacity of modified semi-coking carbon was greatly improved, theadsorption effect difference of modified semi-coking carbon and granular active carbonwas little, and granular active carbon could be replaced by modified semi-coking carbonto save the treatment cost.