Investigation on the effects of siderite and biochar as mixed nutrient sources for bioremediation of synthetic groundwater Cr (VI) pollution

Cr (VI) groundwater pollution poses a significant threat to both agricultural production and human health quality worldwide. Microbial-mediated Cr (VI) reduction offers an eco-friendly and cost-effective strategy. Although siderite and biochar have individually shown promise as electron donors for microbial remediation, their combined use remains underexplored. This study utilized siderite and biochar as mixed nutrient sources to construct bioremediation columns, investigating the microbial community's removal of Cr (VI) within the system. Results revealed that, at an influent Cr (VI) concentration of 0.6 mmol/L, the mixed nutrient source of siderite and biochar achieved a Cr (VI) removal rate ranging from 79.5% to 100%, significantly outperforming the siderite-only and biochar-only groups. XRD spectra confirmed the reduction of Cr (VI) to insoluble Cr (III) through both microbial and chemical pathways. The high microbiota diversity in the siderite and biochar columns, including Aquabacterium, Acidovorax, Reyranella, and Pseudoxanthomonas, was identified as a plausible explanation for the observed high removal rate of Cr (VI). These findings provide a theoretical basis for applying mixed nutrient sources, including siderite, in the removal of Cr (VI) from groundwater, highlighting the potential of this approach for eco-friendly and efficient remediation.