| In the past two decades,researches about the occurrence,fate,toxic effects,transport,and removal of emerging contaminants in the environment has become a hot spot in the environmental field.This thesis first gave a brief introduction of the construction of biofilter and emerging contaminants pollution in the environment,then reviewed biochar-amended biofilter and the-state-of-art of its application in treating various emerging contaminants in wastewater.To understand the interactions between biochar,organic emerging contaminants,and nanoparticles,and how biochar influence the co-transport of them in the medium,the adsorption,retention,and removal mechanism of simulated biochar-amended biofilters for emerging contaminants were studied.The adsorption and desorption behavior of phthalic acid esters(PAEs)on biochar and graphene oxides(GOs)were first evaluated,then the co-transport of GO and dimethyl phthalate(DMP)in saturated medium and how this co-transport behavior could be influenced by biochar as amendment in the medium was also conducted.In order to enhance the removal performance of emerging contaminants by biofilter,we conducted batch adsorption experiment,fixed bed column experiment and microcosm biofilter to comprehensively evaluate the effect of biochar amendment for enhancing the removal of endocrine disruptor bisphenol A(BPA)in biofilter.A fterwards,the long-term removal of various pharmaceutical and personal care products(PPCPs)and their fate in substrate and plant,as well as microbial changes in biochar a,mended biofilters were studied.The results could provide data and theoretical support for the design of biochar-amended biofilter(substrate choosing)and its application in controlling the transport and enhanced removal of emrging pollutants.The main innovations and conclusions are as follows:(1)The adsorption-desorption behavior of PAEs on biochar and graphene oxides,and its mechanism were elucidated,and the effects of biochar amendment on the co?transport and retention mechanism of DMP and GO were investigated.The adsorption and desorption behaviors of biochar and GOs are determined by structure of absorbents and PAEs molecular properties.Hydrophobic effect,?-? EDA interactions and H-bonding contribute to the adsorption of PAEs on biochar and GOs.The reversible adsorption-desorption behavior between GO/RGO is related to their unique two demisional structure,as there was no obvious change in morphologies of GO and RGO before and desorption as revealed by TEM images;while desorption hysteris of PAEs on biochar was found,and the reason may be irreversible pore deformation.In the co-transport of DMP and GO,GO exhibited carrier effect of DMP transport and competed for DMP adsorption sites,thereby increased DMP transport in the column.Biochar could provide abundant adsorption sites to reduce the competitive adsorption of GO to DMP.Meanwhile,due to the strong adsorption capacity of biochar(both saturated adsorption capacity and adsorption affinity are stronger than GO)and the irreversibility of adsorption-desorption,biochar columules can significantly weaken the loading effect of GO on DMP.(2)The adsorption,transport behavior and enhanced removal mechanism of BPA in biochar-amended biofilters were revealed.The excellent removal performance for bisphenol A by biochar-amended biofilter was confirmed by batch adsorption and fixed-bed column study.A good correlation(R2=0.899)between breakthrough time and adsorption constant(k2)and adsorption capacity(Qmax)was found.Rainwater containing 200(pg/L BPA was treated with biofilters amended with different biochars,and the average removal efficiency of BPA was about 5 to 140 times higher than biofilter without biochar amendment.In particular,the biofilters amended with BC700 can effectively remove BPA after 3 months of continuous operation,the removal efficiency was still above 98.4%even under high hydraulic load conditions,and the BPA in treated water can meet the recommended values for drinking water in China.Beside the strong adsorption of biochar,the addition of biochar also promote microbial degradation of BPA in biofilters.(3)The mechanism of efficient removal of trace emerging pollutants by biochar-amended biofilters was pro'ved.The long term operation up to 150 days showed that the amendment of biochar in biofilters can greatly improve the removal of PPCPs(removal efficiency always above 96.7%).Biochar amendment could significantly increase the growth(both height and biomass)of Typha anguslifolia,indicating that biochar amendment could control and inhabit the uptake of PPCPs by plants.Mass balance analysis showed that biochar amendment not only improved the adsorption capacity,but also promoted the microbial degradation to remove PPCPs in biofilters.Alpha and Beta diversity analysis showed that biochar amendment improved the microbial diversity in the biofilters.LEfSe analysis and PICRUSt f'unction prediction analysis revealed that biochar may improve the microbial degradation of PPCPs by promoting microbial signal exchange and metabolism.Additionally,biochar amended biofilters improved the removal of antibiotic resistant genes... |
PDF Full Text Request