Directional enrichment of functional microbial communities and mutual regulation of nitrogen and phosphorus metabolism pathways during rural wastewater treatment using food waste fermentation residue.

Using fermentation residue of food waste (FRFW) as an external carbon source could efficiently promote the rural sewage treatment. In this study, the improvement mechanisms and characteristics of non-sterilized (NS)-FRFW and sterilized (S)-FRFW as supplementary carbon sources in the long-term operation of anaerobic-anoxic-aerobic membrane bioreactor were investigated. The results showed that NS-FRFW and S-FRFW increased TN removal to 7.1 and 6.1 times that of the control, and TP removal to 2.1 and 1.4 times, respectively. FRFW induced microbial community restructuring, resulting in significant enrichment of key functional taxa such as Gammaproteobacteria and Chitinophagaceae. Through quorum sensing, it specifically activated electron transfer (coxA/coxB) and carbon metabolism, thereby increasing the supply of nicotinamide adenine dinucleotide (NADH). This significantly upregulated the expression of amoA and nosZ (4.6 times and 1.4 times for NS-FRFW), promoting ammonia oxidation and denitrification. This study provided a theoretical basis for waste resources recycling and low-carbon wastewater treatment.