Research On The Enhanced Removal Of Organic Pollutants In Sedimnet By Microbe-Electrode Coupling System

Traditional organic pollutant represented by polycyclic aromatic hydrocarbons(PAHs)and the emergent organic pollutants represented by halogenated aromatic antibacterial agent such as triclocarban(TCC)generally coexist in river sediments.Antibacterial agents can inhibit the metabolic activity of indigenous microorganisms,thereby affecting the biodegradation efficiency of typical organic pollutants in the sediment.In order to strengthen the biodegradation of persistent organic matter such as PAHs,a TCC degrading bacteria that can preferentially detoxify TCC and an electrode were applied to construct a microbial-electrode coupling remediation system which can achieve synergistic enhanced removal of PAHs and TCC in the sediment.At the same time,the microbial mechanism of enhanced bioremediation of complexly-polluted sediment by microbe-electrode coupling system was then revealed by combining the electricity generation efficiency of different systems,the removal efficiency of characteristic pollutants and the differences of microbial community structure and diversity.The experimental results indicated that TCC in the coupled system was effectively removed by inoculating TCC-degrading strain Ochrobactrum sp.TCC-2.The removal efficiency of TCC in 128 days was 77.2±1.62%,which was about 4.4 times higher than that of SMFC system without adding degradation bacteria.Meanwhile,the effective detoxification of TCC promoted the removal of PAHs in sediment as well as TOC and TN from overlying water.After 128 days of operation,the removal ratio of six kinds of PAHs such as Phenanthrene in the coupled system increased by 7-30%.The current generation of SMFC was inhibited with the existence of TCC in sediment,while the addition of degrading bacteria TCC-2 recovered it to some extent.At the end of the experiment,difference of the anode potential for three groups also indicated the great bioremediation efficiency of the complexlycontaminated sediment in the coupling system.Microbial analysis based on 16 S rRNA High-throughput sequencing showed that both electrodes and degrading bacteria influenced the composition and structure of indigenous microbial community in sediment.Changes of some indigenous functional bacteria such as Paenarthrobacter and Desulfobulbus should be responsible for the difference in terms of the pollutant removal efficiency and current under different conditions.Fermentation bacteria represented by Chlorobium and electrogenic bacteria represented by Terrisporobacter coexisted in the anode region of SMFC,achieving the metabolic process of macromolecule organic matter,and transferring the electrons obtained to the final electron acceptors for the electricity output.Although TCC-2 was gradually lost in the process of remediation,the continuously efficient removal of organic pollutants in SMFC was achieved by a more functional indigenous microbial community.The enhanced removal of organic and conventional pollutants in river sediment indicates that the microbe-electrode coupled system is promising in the deep purification of contaminated sediment.