Hydrolysis Acidification Pretreatment And Attapulgite Adsorption Advanced Treatment Of Phenol In Wastewater

Phenol is toxic,refractory and carcinogenic,which controlled by China,USA,and other countries as stress control pollutants in water environment.It caused serious threat to human health,biological breeding,water,soil,and atmosphere and so on.Treatment of phenolic wastewater is one of the hard problems to be solved,and the treatment methods mainly include physical and chemical method,chemical method and biological method.It is an inevitable development trend of treatment refractory wastewater by combining biological and physicochemical process.This paper adopted hydrolysis acidification combined with adsorption process to treat phenol wastewater,including hydrolysis acidification as pretreatment process and adsorption as advanced treatment process.Hydrolysis acidification is commonly used in wastewater treatment,however,the removal efficiency of organic matter is not high.In this paper,the traditional hydrolysis acidification technology was modified via adding different coagulants during the cultivation process of acidate bacteria(namely floccular sludge),such as polyacrylamide(PAM),polyaluminium chloride(PAC)and fly ash(FA).The impacts of coagulants on cultivation process of floccular sludge and subsequent effect on wastewater treatment were studied.The main results showed as follows:(1)During the cultivation process of floccular sludge,the highest COD removal efficiency was 90% by adding PAC and FA into floccular sludge,which was 50% higher than adding without coagulants,indicating that COD removal efficiency could be improved by adding PAC and FA;the sum COD removal efficiency of only floccular sludge and only PAC,FA was 60%,indicating it was synergistic effect of PAC,FA and hydrolysis acidification by once every two days dosing 60mg/L,and the activity of acidate bacteria were remarkably enhanced.(2)During the domestication process of floccular sludge,the highest phenol removal efficiency was 55% by adding PAC and FA in floccular sludge,which was 22% higher than adding without coagulants.It is the same treatment effect of phenol and COD by floccular sludge with adding different coagulants.The activity of acidate bacteria and removal efficiency of phenol and COD can be enhanced by adding PAC and FA in floccular sludge.Selecting natural and cheap attapulgite as adsorbent,and it was modified by dodecyl trimethyl ammonium chloride(DTAC).The results showed that attapulgite modified by ultrasonic stirring were better than mechanical agitation method.Optimized absorbent DTAC-attapulgite was made by orthogonal experiment,and the process conditions for dosage ratio of DTAC/attapulgite and ultrasonication time were 40mmol/100 g and 9min respectively.The results on adsorption of phenol in water by DTAC-attapulgite showed as follows:(1)The adsorption capacity of DTAC-attapulgite could be improved twelve times compared with natural attapulgite.Alkaline condition is preferred to absorption phenol.The adsorption process proved to be a fast process,and the adsorption capacity could reach 80% of the maximum adsorption capacity within 5 minutes.Besides,the adsorption process could be well described by the pseudo-second order kinetic model(R2=0.9999).And Langmuir model was found to be applicable to the prediction of the isothermal adsorption(R2>0.98),revealing the adsorption was monolayer.The thermodynamic experimental results showed that the adsorption was a spontaneous,exothermic and entropyreduction process.(2)Natural attapulgite and DTAC-attapulgite were characterized by FTIR and XRD.The results showed that C-H organic functional groups successfully attached to DTAC-attapulgite,suggested that attapulgite was successfully modified by DTAC and didn't change its crystal structure with greater hydrophobicity.(3)DTAC-attapulgite as adsorbent was applied to adsorb effluent containing phenol which was treated by floccular sludge cultivating with PAC and FA.Considering both the effects and economic benefits,the removal efficiency of phenol can reach 80%.The removal efficiency of phenol was 91% after treated by hydrolysis acidification combined with adsorption process at phenol initial concentration of 100mg/L.The combination of the two kinds of technology had greatly increased the removal efficiency of phenol.