Sustainable remediation of butyl xanthate-contaminated mine wastewater by combining emergent macrophyte Cyperus alternifolius with a versatile bacterial isolate

Abstract

Butyl xanthate (BuX) is an emerging pollutant due to wide use as flotation collector, posing a serious threat to ecosystem health in mining areas. Here we develop a combinational plant-microbe remediation strategy for restoration of BuX-contaminated mining areas. A novel bacterial strain that completely degraded up to 1000 mg/L of BuX within 12 h was isolated and identified as Pseudomonas monteilii W50. It was found to harbor good tolerance to extreme environmental conditions and multiple plant growth-promoting traits such as phosphate and potassium solubilization, indole-3-acetic acid and gibberellin production, and cellulose degradation. This strain can colonize in the rhizosphere of an emergent macrophyte Cyperus alternifolius, improving removal of BuX and chemical oxygen demand (COD) from simulated wastewater. Compared to the phytoremediation alone, the removal of BuX and COD increased from 70 % to 98 % and from 21 % to 46 % respectively in the combined remediation The strain W50 protected the macrophyte from the phytotoxicity of BuX and the macrophyte provided it with a suitable habitat for return, benefiting each other. Compared to the individual treatment using C. alternifolius or strain W50, the combinational treatment significantly improved the plant growth and the residence of inoculated bacteria. Overall, C. alternifolius and strain W50 are the perfect combination for efficient and sustainable remediation of BuX-contaminated mine wastewater, overcoming the constraints of individual phytoremediation or bioaugmentation methods.