The disinhibition effect of iron-based particles on anaerobic digestion of florfenicol-containing cow manure: Performance and mechanism

Abstract

The overuse of antibiotics has caused problems such as environmental pollution, increased antibiotic resistance of pathogenic bacteria, and inhibition of engineered microbial processes such as anaerobic digestion (AD). At present, mitigating the inhibition of antibiotics on the process of microbial recycling of organic matter by using additives has always been a research hotspot. In this study, the effects of the addition of three iron-based particles including zero-valent iron (ZVI), Fe2O3 and Fe3O4 on the biogas yield during the AD of cow manure containing florfenicol (FLO) were studied. It was found that by alleviating the acid accumulation, the addition of low-concentration ZVI, Fe2O3 and high-concentration Fe3O4 enhanced the maximum methane production rate of FLO-containing cow manure during AD to 3.5, 1.7 and 3.6 times, respectively, while high concentration of ZVI will lead to the crash of the AD system due to the rise of pH. Within the concentration range of iron-based particles dosed in this study, the Fe3O4 dosage showed a significant positive correlation with the cumulative methane production enhancement rate (p < 0.01). The sum of the relative abundances of Limnobacter and Pseudomonas was correlated with the absolute abundance of floR gene with the Pearson correlation coefficient of 0.9457 (p < 0.01), indicating the possibility of these two genera being the potential host bacteria for floR gene.