Enhanced denitrification and p-nitrophenol removal performance via hydrophilic sponge carriers fixed with dual-bacterial: Optimization, performance, and enhancement mechanism.

Effective treatment of industrial wastewater containing complex pollutants, such as nitrate (NO 3 --N) and organic pollutants, remains a significant challenge to date. Here, a strain Nocardioides sp. ZS2 with denitrification and degradation of p -nitrophenol (PNP) was isolated and its culture conditions were optimized by kinetic analysis. Hydrophilic sponge carriers were prepared using polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), and chitosan (CS) to construct bioreactors. Furthermore, to further enhance the PNP degradation and denitrification performance of bioreactors, Pseudomonas stutzeri GF2 with denitrification capability was introduced. The results revealed that the removal efficiencies of PNP and NO 3 --N reached 97.9 % and 91.9 %, respectively, when hydraulic retention time (HRT) of 6 h, C/N of 2.0, and pH of 6.5. The bioreactor exhibited stable denitrification performance even with fluctuations in the influent PNP concentration. The potential functional prediction results revealed that the abundance of amino acids, fatty acids, and carbohydrates increased as the influent C/N decreased, reflecting a tendency of the microbial community to adjust carbon source utilization to maintain cell growth, metabolic balance, and resist adverse C/N environments. This research provides new insights into the effective removal of organic pollutants and NO 3 --N in wastewater treatment. [Display omitted] • A novel Nocardioides sp. ZS2 with the ability to remove PNP and NO 3 --N was isolated. • PNP degradation by-products alleviate NO 2 --N accumulation in denitrification process. • A novel hydrophilic sponge biocarrier was prepared by hydroxyaldol reaction. • Dual bacterial collaboration enhanced the removal efficiencies of NO 3 --N and PNP. • The increase in PNP concentration promoted substance transport and metabolism. [ABSTRACT FROM AUTHOR]