Fungal Electrochemical Remediation of Herbicide-contaminated Soil:Preliminary Study on Degradation Kinetics
[Objective]Microbial fuel cell(MFC),which produces electricity while removing pollutants,is a promising means of ecological restoration.We aim to construct a fungal-augmented MFC device,compare the effects,advantages and disadvantages of electrokinetic(EK),fungal and MFC remediation against herbicides in the polluted soil,and explored the application potential of MFC in the remediation of organic pollutants.[Method]A novel MFC with fungal bioaugmentation was designed.The contaminated soil by two herbicides was remediated by three methods of EK,fungi and MFC remediations,and the screened and domesticated Talaromyces dalianensis and Myrothecium verrucaria strains were implemented in the latter two approaches.The effect of fungal augmentation on the removal of herbicides was studied.Soil pH,electrical conductivity,herbicide removal,and MFC electrical performance were quantified,and degradation products of two herbicides were identified by gas chromatography-mass spectrometry.[Result]In EK remediation,when simulated electrolyte,carbon fiber and 10 V were applied for 7 d,the removal rate of florpyrauxifen-benzyl(F)and haloxyfop-P(H)was 71%and 38%,respectively.Compared with H,F was more easily degraded,and fungal and MFC treatments completely removed it.Compared with T.dalianensis,M.verrucaria strain had better degradation capacity to both herbicides.MFC based on two fungi had the removal rate of 62.5%and 24.1%respectively toward H.The degradation product of F and H was halauxifen and 4-methoxybenzyl acetate,respectively,and the degradation pathways and kinetics were speculated.The degradation of F by three methods and the degradation of H by EK followed the first-order kinetic reaction,while the degradation of H by fungi and MFC followed the second-order reaction.[Conclusion]Compared with EK and fungal remediations,MFC remediation had a better effect,which can remediate the soil without the need for additional power supply,making it a cost-effective self-sustaining remediation strategy.
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