Efficiency And Mechanism Of Phenolic Wastewater Treatment By An Anaerobic Ceramic Membrane Bioreactor

Phenols and nitrogenous heterocyclic compounds are typical toxic and refractory organics in the effluents from coal gasification,petroleum refining,coking,and pharmaceutical manufacturing.Present studies have shown that phenol and quinoline are toxic,mutagenic,carcinogenic,and can threat the living beings and environment even at low concentrations.For this reason,it’s necessary to explore an economical and efficient processing method.Activated sludge process could operate well when treating phenol-containing wastewater under a low concentration,but it would be seriously inhibited by high concentration of phenol.Anaerobic process was an energy-efficient and economical technology,but it needed a long start-up time.In this paper,the phenol-containing wastewater was treated by an anaerobic baffled ceramic membrane bioreactor(ABCMBR).The start-up,membrane fouling control and the effects of high concentration of phenol were studied.At first,the anaerobic baffled reactor was inoculated with activated sludge from a full scale municipal sewage treatment plant.The concentrations of phenol and quinoline were 500 mg/L and 50 mg/L,respectively.The removal of phenol and quinoline both reached 99% after operating stably for 30 days,which indicated the quick start-up of ABCMBR was realized.According to the analysis of bulk sludge and cake layer,the cake layer had higher SUR(substrate utilization rate)and SMA(specific methanogenic activity).In addition,the cake layer had higher abundance of microbial community than bulk sludge.Moreover,the role of scoured cake layer on the removal of phenol and quinoline was estimated by equations,and the contribution of cake layer on improving activities of bulk sludge was seriously underestimated.Secondly,the effects of granular active carbon(GAC)and polyaluminum chloride(PACl)addition on the menbrane fouling control were studied.The results showed the GAC could improve the membrane performance and delay the rate of membrane fouling in a short time,but PACl was better for long-term running of reactor.The addition of PACl could significantly influence the ratio of protein and polysaccharide,and improve the filtering ability of sludge.In addition,the cake layer was looser than the one with GAC.Finally,the ABCMBR was running under a high concentration of phenol.The results showed that the sludge could still keep a high activity when the influent of phenol was 1 to 3 g/L,and the removal of phenol and quinoline were more than 97.6% and 95.6%,respectively.Furthermore,when the concentration of phenol was 4 to 5 g/L,ABCMBR succeeded to work well.The removal of phenol and quinoline were around 97.6% and 95.6% at the phenol load of 0.19 g/(g VSS·d).The analysis of microbial community structure indicated that the dominant genera of anaerobic phenol-degrading communities transferred from Aminicenates(26.09%),Proteobacteria(21.5%),Chloroflexi(13.38%),Firmicutes(13.26%)to Proteobacteria(50.51%),Bacteroidetes(14.25%),Chloroflexi(8.67%),Thermotogae(8.02%),and the main methanogens transferred from Methanothrix(41.54%),Methanolinea(29.39%),Methanospirillum(11.86%)to Methanolinea(45.87%),Methanothrix(37.94%),Methanosphaerula(6.54%).