Main content area

Effective bioremediation of Cu(II) contaminated waters with immobilized sulfate‐reducing bacteria‐microalgae beads in a continuous treatment system and mechanism analysis

Li, Yongchao, Yang, Xiaoyan, Geng, Bing, Liu, Xue
Journal of chemical technology and biotechnology 2018 v.93 no.5 pp. 1453-1461
Scenedesmus obliquus, biodegradability, bioreactors, bioremediation, carbon, chemical oxygen demand, copper, fermentation, heavy metals, hydrolysis, immobilized cells, mass transfer, microalgae, strength (mechanics), sulfate-reducing bacteria, sulfates, sulfides, volatile fatty acids, wastewater, water pollution
BACKGROUND: Microalgae which have greater biodegradable fractions than other organics were chosen as a carbon source for sulfate‐reducing bacteria (SRB). Immobilized SRB–microalgae beads were then prepared and used for bioremediation of synthetic copper mine wastewater. RESULTS: Hydrolysis fermentation of the microalgae was observed and it was noted that the microalgae were first degraded to volatile fatty acids by co‐existing fermentative bacteria; they then served as a carbon source for SRB. Freshly prepared immobilized SRB beads not only possessed high mechanical strength and mass transfer ability, but also showed better sulfate reduction than that of suspended SRB. Immobilized SRB‐Scenedesmus obliquus beads packed in the upflow bioreactor were suitable for the treatment of copper mine wastewater, as shown by the high removal efficiency of their sulfate (182.17 mg SO₄²‐ g‐¹ microalgae day‐¹) and copper ions (45.28 mg Cu²⁺ g‐¹ microalgae day‐¹), and low discharge of chemical oxygen demand. After the reaction, metal sulfides were not produced on the bead surfaces, but likely within them. CONCLUSIONS: The anaerobic bioreactor, filled with immobilized SRB‐Scenedesmus obliquus beads, demonstrated excellent removal efficiency and low discharge of chemical oxygen demand, which may provide a promising strategy for dealing with heavy metal pollution in water. © 2017 Society of Chemical Industry