Mechanism and application of a nitrifying bacteria enrichment carrier in remediation of polluted rural micro-water bodies

To address the issues of NH3-N and COD pollution， slow natural growth of nitrifying bacteria， and unstable treatment efficiency in rural micro-water bodies， this study examined a polycaprolactone （PCL）-based nitrifying bacteria enrichment carrier， focusing on environmental adaptability， pollutant removal efficiency， and microbial enrichment mechanisms. Key findings include： 1） The carrier showed excellent environmental adaptability at a 0.1% dosage. It performed well within a temperature range of 10 ℃ to 30 ℃ and a pH range of 6 to 9. It could achieve a significant NH3-N removal under low-temperature and acidic/alkaline conditions. 2） The carrier enabled simultaneous NH3-N and COD removal， with a removal rate reaching 78.39% for NH3-N and 71.41% for COD，respectively. 3） The carrier surface enriched nitrifying functional bacteria， including Dechloromonas， norank_f__Anaerolineaceae， and Phreatobacter. Nitrification-related functional genes （amoA and nxrA） showed increased copy numbers. Microbial activity is significantly enhanced.