Simultaneous pollutant removal and organic matter sequestration by coral sand-pyrite-based electroactive constructed...

The development of integrated solutions for sewage treatment and soil restoration in remote regions remains a challenge. This study innovatively designed coral sand-pyrite-based electroactive constructed wetlands (E-CWs) to synchronize wastewater purification and organic matter (OM) enrichment. Metagenomic analyses revealed that the addition of pyrite increased the abundance of iron redox-related genes, whereas coral sand salinity promoted the enrichment of functional bacteria for OM decomposition. Furthermore, the combined substrate comprising coral sand and pyrite facilitated the adsorption and sequestration of OM, while providing a stable environment for microorganisms. This achieved dual objectives: efficient chemical oxygen demand removal (90.6 ± 2.4 %) from sewage and substantial OM sequestration in substrates (total organic carbon: 2.9-4.8 %). This study achieved sewage treatment through the combination of coral sand and pyrite as substrates of E-CWs and enhanced the OM content of the substrates, contributing to the improvement of local soil infertility.