Microbial carbon, nitrogen, and phosphorus metabolism and resistance mechanisms in constructed rapid infiltration systems for treating mineral processing wastewater under low temperature

In this study, constructed rapid infiltration systems (CRIS) packed with coke or modified red mud were used to treat mineral processing wastewater (MPW) containing aniline aerofloat (AAF) and ammonium dibutyl dithiophosphate (ADD) at 10 °C. Microbial community dynamics and metagenomics were analyzed to investigate elucidate system responses under low temperature stress. Under the tested conditions, the coke-packed systems (A and C) showed relatively higher chemical oxygen demand (COD) removal, while modified red mud-packed systems (B and D) exhibited greater efficiency in removing NH₃-N and total phosphorus. The differences in pollutant removal efficiencies appeared to be associated with distinct microbial communities. In columns A–D, Pseudomonadota abundance levels were 58.02%, 91.23%, 79.51%, and 82.21%, respectively, which suggested a potential correlation with the observed differences in NH 3 -N and TP removal. Functional gene analysis showed pfkA abundance (0.11%, 0.04%, 0.01%, 0.002% in A–D) partly explained the relatively superior COD removal observed in coke-packed systems in this study. Microorganisms expelled the flotation reagents by employing efflux mechanisms and responded to low temperature by deploying molecular chaperones (e.g. , HSPA ) that facilitated cold protection mechanisms, maintaining mRNA stability, protein folding, and metabolic regulation. These adaptive strategies appeared to contribute to stable CRIS operation under combined low-temperature and AAF/ADD stress. The findings may offer practical guidance for CRIS applications to treat flotation reagent-containing MPW in low-temperature environments.