RESUMO
Sulfate content in mining wastewater can reach concentrations over 2,000 mg·L-1, which is considered as a pollutant of concern. In this article, two cyanobacteria species were cultured using highly sulfated wastewater (3,000 mg·L-1) as the culture medium. This investigation aimed to analyze the sulfate bioremediation potential of microalgae while enhancing the uptaking of this pollutant through the design of a novel nutritional medium. The results obtained show the suitability of Arthrospira maxima as a bioremediation organism of sulfated wastewater. The appropriateness of this organism is based on its great growth performance when cultured in this residue, 2.16 times higher than the initial value. Moreover, the initially obtained sulfate reduction, 23.3%, was significantly enhanced to a final removal of 73% (2,247 mg·L-1). In addition, scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to evaluate sulfur crystallization. To the best of our knowledge, there are no previous works focused on microalgal sulfate removal that have reached such an uptaking rate. Accordingly, this study presents the highest performance on sulfate microalgal bioremediation published to date. Our findings suggest that A. maxima can be cultured for sulfated wastewater bioremediation while showing a removal yield that is theoretically sufficient for industrial applications.
To the best of our knowledge, this is the first study focused on the bioremediation potential of Arthrospira genre (Spirulin) for highly sulfated wastewaters depuration. Moreover, according to the available data, our study achieved the highest sulfate removal rate by using microalgae as a bioremediation organism. Thus, we strongly believe that our investigation provides up-to-date data in terms of mining wastewaters bioremediation, which can cause a strong impact on how these residues are managed.