Changes in Microbial and Metabolic Pathways of Solidifying Manganese and Removing Nitrogen from Electrolytic Manganese Residue by the Sulfate-Reducing Bacteria

Electrolytic manganese residue (EMR) contains a large number of soluble manganese ions and ammonia nitrogen, which seriously endangers the surrounding environment. Solidifying manganese and removing nitrogen has become the primary method for controlling EMR. In this study, an EMR stacking yard in Guangxi was used as a study site to study the solidification of soluble manganese ions and the removal of ammonia nitrogen by mixed bacteria under natural conditions. Further, Illumina MiSeq high-throughput sequencing technology was used to analyze the difference in microbial community structure and function. The results showed that the solidification rate of soluble manganese ions in the remediation area reached more than 99%, and the removal effect of ammonia nitrogen in EMR was obvious. The mechanism showed that manganese in EMR was solidified into MnS. High-throughput sequencing results showed that the abundance of sulfate-reducing bacteria in the remediation area was significantly higher than that in the control area. The functional groups predicted by the FAPROTAX database showed the functional groups related to N and S reduction increased significantly in the remediation area, while the functional groups related to N and S oxidation decreased. Microorganisms in the remediation area promoted the circulation of N and S elements, and the vegetation on the surface of the residue field in the remediation area was also restored.