Efficient Removal of Butachlor and Change in Microbial Community Structure in Single-Chamber Microbial Fuel Cells.

Xiaojing Li,Yang Sun,Xiaodong Chen,Xiaolin Zhang,Yongtao Li,Liping Weng,Yue Li,Lixia Zhao

doi:10.3390/ijerph16203897

Abstract

Microbial electrochemical technology provides an inexhaustible supply of electron acceptors, allowing electroactive microorganisms to generate biocurrent and accelerate the removal of organics. The treatment of wastewater contaminated by butachlor, which is a commonly used chloroacetamide herbicide in paddy fields, is a problem in agricultural production. In this study, butachlor was found to be removed efficiently (90 ± 1%) and rapidly (one day) in constructed single-chamber microbial fuel cells (MFCs). After the addition of sodium acetate to MFCs with butachlor as the sole carbon source, electricity generation was recovered instead of increasing the degradation efficiency of butachlor. Meanwhile, the microbial community structure was changed in anodic and cathodic biofilms after the addition of butachlor, following the bioelectrochemical degradation of butachlor. High-throughput sequencing showed the proliferation of Paracoccus and Geobacter in MFCs with butachlor as the sole carbon source and of Thauera butanivorans in MFCs with butachlor and sodium acetate as concomitant carbon sources. These species possess the ability to oxidize different substituents of butachlor and have important potential use for the bioremediation of wastewater, sediments, and soils.

Highlights

Chloroacetamide herbicides, e.g., alachlor, acetochlor, butachlor, and metolachlor, are commonly used herbicides in rice, corn, soybean, and many other crops for controlling annual grass and broadleaf weeds [1,2]
microbial fuel cells (MFCs) with NaAC as the sole carbon source were used as the control for electricity generation and microbial community analysis, while the removal rate of butachlor in a sample bottle under the same conditions was used as the control for the non-MFC treatment
52–53% removal rates were obtained in the corresponding controls which were placed in the same conditions without MFC treatment

Summary

Introduction

Chloroacetamide herbicides, e.g., alachlor, acetochlor, butachlor, and metolachlor, are commonly used herbicides in rice, corn, soybean, and many other crops for controlling annual grass and broadleaf weeds [1,2]. Exterior drainage and outdoor rainwater are inevitably polluted by residues of butachlor and its degradation metabolites, which pose a threat to the surrounding environment, especially ground and surface waters, since they are highly toxic to some aquatic organisms [3] and are potentially carcinogenic (e.g., butachlor caused stomach tumors in rats [4]). This risky wastewater needs to be treated before discharge.

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Methods

Results

Discussion

Conclusion