Microorganisms play a crucial role in biogeochemical cycling within wetland ecosystems. Soil-environment-mediated seasonal changes in microbial structure require further investigation. However, the factors driving seasonal variations in the microbial abundance and diversity in the Daihai wetlands remain unclear. This study employed high-throughput sequencing technology to examine the bacterial community structure and diversity in the lakeshore zone of Daihai across different seasons and to explore the seasonal variations in the bacterial community structure and the influence of driving factors. The results indicated that Pseudomonadota and Bacteroidota dominate in spring and Pseudomonadota abundance further increases in summer, while organic-matter-decomposing microorganisms (e.g., Actinobacteriota and Bacteroidota) dominate in autumn. Microbial diversity indices indicated a significantly greater diversity in spring than in summer and autumn (p < 0.05). Changes in environmental variables were strongly associated with bacterial community changes, with variations in total nitrogen, ammonium nitrogen, and soil moisture content being identified as potential key factors influencing seasonal bacterial diversity trends. Furthermore, bacterial community assembly in spring is driven by both stochastic processes and environmental selection, suggesting that abundant nutrients and organic matter promote bacterial diversity. The findings of this study provide a theoretical basis for wetland ecosystem restoration and conservation.

When treating municipal wastewater, nitrogen removal is often limited due to low C/N, which needs to be compensated for by additional carbon source injections. This study investigated the feasibility of using industrial-waste polyglycolic acid (PGA) as a carbon source for denitrification in an SBR to obtain an economical carbon source. The results revealed that an optimal denitrification performance in a methanol-fed activated sludge system was achieved with a PGA dosage of 1.2 mL/L, a pH of 7–8, and a dissolved-oxygen (DO) concentration of 3 ± 0.5 mg/L. Under these conditions, all quality parameters for effluent water met the required criteria [COD < 50 mg/L; TN < 15 mg/L; NH₄⁺-N < 5(8) mg/L]. PGA enhanced the variety and richness of microbial communities, thereby markedly increasing the relative abundance of major phyla such as Proteobacteria and Bacteroidota and major genera such as Paracoccus and Dechloromonas. Furthermore, PGA upregulated the expression of nitrogen-metabolism-related genera, including amo, hao, nar, and nor, which improved the denitrification performance of the system. This study provides a reference for applying PGA as a carbon source for low-C/N-wastewater treatment and solid-waste utilization.

Aquaculture wastewater is rich in nutrients such as nitrogen and phosphorus. If discharged directly without treatment, it can cause eutrophication of water bodies and the proliferation of algae. This study explores the treatment of aquaculture wastewater using cerium nitrate and hydrogen peroxide. To improve the treatment efficiency of ammonia and nitrite in aquaculture wastewater, a Box–Behnken design with three factors at three levels was used to optimize the process of treating aquaculture wastewater with cerium nitrate and hydrogen peroxide. The optimal process conditions for removing ammonia and nitrite were determined to be a Ce(NO₃)₃ dosage of 0.18 g/L, an H₂O₂ reaction concentration of 1.0%, and a reaction time of 30 min. Under the optimal reaction conditions, the degradation rate of ammonia and nitrite can reach 80% or more. Finally, high-throughput sequencing technology was used to explore the impact of cerium nitrate and hydrogen peroxide treatment on microbial community structure and metabolic pathways. The results showed that, at the phylum level, the dominant positions of Actinobacteriota, Proteobacteria, and Bacteroidota were maintained throughout the entire culture period. At the genus level, the relative abundance of the hgcI_clade genus under Actinobacteriota significantly increased, becoming the main dominant genus throughout the culture period. Under the condition of adding cerium nitrate and hydrogen peroxide, the metabolic functions of the microbial community were enhanced. The addition of cerium nitrate and hydrogen peroxide increased the abundance of key nitrogen metabolism genes such as amo, hao, and nap, thereby enhancing the potential nitrification/denitrification capabilities of microorganisms. The combination of cerium nitrate and hydrogen peroxide showed positive effects in the treatment of aquaculture wastewater, providing a new strategy for the green treatment of wastewater.