Synergistic effects of controlled-release oxygen and immobilized composite microorganisms on black-odor water remediation.

Black-odor water remediation is often limited by insufficient oxygen supply, sediment-derived pollutant release, and unstable microbial activity. To overcome these limitations, this study developed a synergistic remediation system combining stearic acid (SA)-coated calcium peroxide (CaO2) oxygen releasers with composite microorganisms immobilized on FeCl3-modified zeolite. The SA coating regulated CaO2 dissolution and provided a gradual oxygen supply, while the modified zeolite enhanced microbial retention and pollutant enrichment. The optimized system achieved effective remediation of simulated black-odor water, with removal efficiencies of 97.94% for NH4+-N and 94.62% for total nitrogen (TN) in overlying water, and 67.41% for acid volatile sulfide (AVS) and 57.68% for TN in sediment. Compared with individual treatments, the coupled system showed improved overall pollutant removal performance, particularly for nitrogen, and remained effective under low-temperature conditions. Microbial community analysis suggested that the enhanced remediation performance was associated with the formation of favorable redox microenvironments and the potential involvement of nitrogen and sulfur transformation pathways, including nitrification, denitrification, sulfur-driven denitrification, and anaerobic ammonium oxidation. This study provides a feasible strategy for improving the stability of in situ black-odor water remediation by integrating controlled oxygen release with microbial immobilization.