Removal of heavy metals and hydrocarbons by microalgae from wastewater in the steel industry

Steel-industry effluents contain hazardous compounds such as heavy metals and hydrocarbons, which can damage the environment. Traditional remediation technologies generate secondary impacts and, therefore, developing more sustainable methods is imperative. In this work, the tolerance capacity of Tetradesmus obliquus, Chlorella sorokiniana, Chlorella vulgaris, Arthrospira platensis and Arthrospira maxima (spirulina) to steel hot-rolling wastewater was tested through their exposure to increasing concentrations of residue. Based on the results obtained, A. maxima was cultured in presence of wastewater and scaled to semi-industrial production systems. Influence of microalgae growth on wastewater composition was evaluated by the end of the experiment by measuring concentrations of contaminants of concern (iron and hydrocarbons). Results showed a reduction of hydrocarbons and iron of 75 and 97.9%, respectively. The findings obtained in this study stablish that spirulina cultures might be used as a novel and environmentally sustainable bioremediation tool for steel-industry wastewater.