Removal Effect Of Tetrachlorobisphenol-A In A Combined Process Of SBBR And CW

With the upgrading of electronic products,the amount of electronic wastes increased rapidly,and a large number of toxic and harmful organic pollutants were released into the environment due to the e-waste dismantling.As one of organic pollutants,tetrachlorobisphenol-A(TCBPA)has been widely concerned around the world.Regarded as the widely used halogenated flame retardant,TCBPA can be released into the environment such as soil,river,urban sewage treatment systems and even the drinking water systems,and do harm to humans during its processes of transportation,using,disposal and degradation.In this study,firstly,a combined process of Sequencing Biofilm Batch Reactor(SBBR)and Constructed Wetland(CW)was studied,which can be applied to the sewage interception and reclaimed water system.Secondly,based on the fact of TCBPA pollution in water environment,the removal efficiency of TCBPA by combined process and the possible influence of TCBPA on urban sewage treatment system were discussed.The study results of removal of conventional pollutants in domestic wastewater by combined process showed that when aeration time was 75 min,aerobic time was 240 min and dissolved oxygen was 3.07-4.09 mg L-1,with the operation mode of CW included a seepage stage of 12 h and a dormant stage of 12 h,the combined process has reached the standard and achieved the lowest energy consumption.Under this operating condition,the removal rates of COD,NH4+-N,TN and TP in SBBR system were 94.6%,94.8%,85.4%and 61.1%,respectively.In CW system,the removal of COD,NH4+-N,TN and TP over the operation period was achieved at average rates of 39.3%,47.3%,61.5%,70.7%,respectively.In the combined process,the average effluents COD,NH4+-N,TN and TP concentration were 13.89,0.535,2.047 and 0.286 mg·L-1,corresponding to the removal rates of 96.7%,97.3%,94.4%,88.6%,respectively.For study of the removal of TCBPA in simulated domestic sewage,the results showed that when the TCBPA concentration was 200 μg· L-1,the removal efficiency of TCBPA in SBBR,CW and combined progress was 42.34%,50.08%and 70.53%,respectively.Three kinds of substances on the adsorption of TCBPA were studied as well,the results showed that when the TCBPA concentration was 200 μg·L-1,the adsorption rate of TCBPA of this three kinds of substances was ordered as carbonfiber>soil>ceramsite,and the adsorption capacity of this three kinds of substances was ordered as carbonfiber>soil≈ ceramsite.The research of the impacts of TCBPA on the microbial community structure in the SBBR and CW was carried by MiSeq sequencing technology.The results showed that indices such as OTU number,Chao,Shannon-Wiener of the microfloras in SBBR and soil biofilm were decreased,which indicates that TCBPA may have an inhibitory impaction on microbiologic community.Furthermore,the study of the structure of microbial community showed that TCBPA can influence the phylum,class,genus of microbial community in carbon fiber biofilm,soil and ceramsite in a certain degree.