In this study, a laboratory-scale zero-valent iron (ZVI)-enhanced hydrolytic acidification system was established to treat the comprehensive wastewater from Nanjing Jiangbei New Material Science Technology Park. Results indicated that the ZVI-enhanced hydrolytic acidification system achieved a maximum COD removal efficiency of 95.0%, surpassing the performance of the system without ZVI by 12.2%. Microbial community analysis revealed the enrichment of electrogenic bacterium Bacteroidetes_vadinHA17 and typical hydrogenotrophic methanogen Methanobacterium due to ZVI addition. High-throughput sequencing combined with PICRUSt2 analysis demonstrated acetate production was promoted, and butyrate and propionate production was inhibited. Additionally, Oxygen Uptake Rate-based toxicity assays revealed the hydrolytic acidification system transitioned the wastewater of three enterprises from low toxicity to non-toxic status and two from high to low toxicity. While the ZVI-enhanced hydrolytic acidification system successfully reduced the toxicity of all highly and low toxic wastewaters to non-toxic levels.
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