Degradation pathway and microbial mechanism of high-concentration thiocyanate in gold mine tailings wastewater

Abstract

As one of the inorganic pollutants with the highest concentration in the waste water of gold tailings using biohydrometallurgy, thiocyanate (SCN^-) was effectively degraded in this research adopting a two-stage activated sludge biological treatment, and the corresponding degradation pathway and microbial community characteristics in this process were also studied. The results showed that SCN^- at 1818.00 mg L^-1 in the influent decreased to 0.68 mg L^-1 after flowing through the two-stage activated sludge units. Raman spectroscopy was used to study the changes of relevant functional groups, finding that SCN^- was degraded in the COS pathway. Based on 16S rRNA high-throughput sequencing technology, the microbial diversity in this system was analyzed, and the results indicated that Thiobacillus played a major role in degrading SCN^-, of which the abundance in these two activated sludge units was 32.05% and 20.37%, respectively. The results further revealed the biological removal mechanism of SCN^- in gold mine tailings wastewater.

Fig. 1. Raman spectrum analysis of water quality—①: regulating tank; ②: primary activated sludge unit; ③: secondary activated sludge unit.

Fig. 2. Venn diagram of microbial community—A: primary activated sludge unit; B: secondary activated sludge unit.

Fig. 3. Microbial classification at a Phylum level—A: primary activated sludge unit; B: secondary activated sludge unit.

Fig. 4. Microbial classification at a Family level—A: primary activated sludge unit; B: secondary activated sludge unit.

Fig. 5. Heatmap of microbial community (A: primary activated sludge unit; B: secondary activated sludge unit).