Bioelectrochemical removal of tetracycline from four typical soils in China: A performance assessment

Exposure to tetracycline in soil causes microbial mutations. Soil microbial fuel cells (MFCs) can promote the degradation efficiency of contaminants while generating bioelectricity under anaerobic conditions. MFC performance varies amongst different types of soils due to distinctive soil properties. This study assesses the performance of soil MFCs filled with four typical Chinese soils and explores key factors regulating bioelectricity generation and tetracycline degradation. Except for the MFCs filled with black soil, tetracycline degradation rates improved in soil MFCs, particularly in those filled with Chao soil, which enhanced the degradation rate by 39% relative to the corresponding control. Additionally, soil MFCs filled with Chao soil exhibited the highest charge output of 1347 ± 357C, which was 100-499% higher than that of MFCs with other soils. According to redundancy analysis, soil particle size, pH, conductivity and dissolved organic carbon content showed positive association with tetracycline degradation and charge output, while the adsorption of tetracycline had a negative association with degradation rate. Thus, the adsorption of tetracycline restricted its removal efficiency in soil MFCs, and high soil conductivity and large particle size promoted electron transfer, enhancing biocurrent intensity, which increased tetracycline degradation efficiency.