Study On The Effect Of Carbon Sorbents On Polychlorinated Biphenyls Contaminated Sediment And Its Biological Effect

Sediment is the source and sink of environmental pollutants.Polychlorinated biphenyls(PCBs)is a kind of persistent organic pollutant that is mainly concerned whether domestic or abroad.According to the literatures,the concentration of PCB is excessive in many place of China.In situ repair agent treatment of sediment is a kind of technology,which is advanced,high efficiency and clean.However,this technology is not widely used,the reason is that the long-term governance effect and biological effect after treatment is not clear.In this research,we use power plant ash,raw carbon,charcoal and shell activated carbon as the carbon sorbents,at the same time,passive sampling with low density polyethylene film(LDPE)was used as the monitoring method,which can compare the PCB pollution treatment effect of these four kinds of carbon sorbents.At the same time,the larvae of anopheles mosquitoes were used to indicate the biological effect of these four kinds of carbon sorbents.The purpose of the study is to select an carbon sorbents with better treatment effect and less adverse effects on biology,the conclusions are as follows:(1)The physical and chemical properties of these four kinds of carbon sorbents are different.The pore structure of charcoal and fruit shell is more than raw carbon and power plant ash.The contribution rate of micropore volume of charcoal,fruit shel,raw carbon and power plant ash is 14.44%,13.71%,10.88%,1.90%respectively,the BET surface area of fruit shel,charcoal,raw carbon and power plant ash is 399.78 m2/g,369.36 m2/g,95.27 m2/g and 8.55 m2/g,respectively.(2)The total PCB removal rate in pore water of charcoal,fruit shel,raw carbon and power plant ash is 97.34%,94.20%,89.18%,81.25%respectively,and the sequence of treatment effect is similar to the sequence of BET surface area of carbon sorbents,which indicate that the treatment effect of carbon sorbents is influenced by the BET surface area of carbon sorbents.The treatment effect of these four kinds of carbon sorbents is different,the removal rate of pore water PCB of power plant ash and raw char was significantly negatively correlated with PCB molecular diameter and octanol-water partition coefficient(P<0.05);however,the removal rate of pore water PCB of charcoal and shell activated carbon was not significantly negatively correlated with PCB molecular diameter and octanol-water partition coefficient(P>0.05).The increase of dosage of remediation can significantly improve the treatment effect of power plant ash,but it has little effect on charcoal and fruit shell activated carbon.The dynamics research of PCB pollution sediment indicates that the second-order kinetic equation can well match the treatment process of carbon sorbents(R2>0.99),and the sequence of qe is similar to the sequence of BET surface area of carbon sorbents,indicating that thetreatment effect of carbon sorbents is influenced by the BET surface area of carbon sorbents.(3)The four kinds of carbon sorbents have inhibitory effect on the survival and growth of organisms,leading to a decrease in SOD enzyme activity and an increase in CarE enzyme activity.The inhibitory effect of power plant ash is the strongest,followed by is the raw carbon and shell activated carbon,and the inhibitory effect of charcoal minimum.The process of sediment treatment of raw charcoal,charcoal,and shelled activated carbon can alleviate the adverse effects of PCB contaminated sediment on the organisms,and the charcoal has the strongest relief effect.With the extension of the treatment time,the inhibitory effect on the organisms is reduce,while the treatment time is extend.However,When the dosage of carbon sorbents increases,the inhibitory effect is strengthened.Integrating the treatment effect and biological impact,charcoal under the dosage of 5%is the best carbon sorbents,which have a better treatment effect of PCB,while the biological impact is lest.The treatment effect of power plant ash is worst,meanwhile it have a serious inhibitory effect on organism,which is not recommended for the actual treatment process.