The role of algae in heavy metals removal from mining wastewater

Abstract

Nature is the key solution for human need and problems emerging from man-made structures.

Inefficiently purified industrial and municipal wastewater discharges cause so far many prominent pollution cases.

In this work experimental scale algae turf scrubbers (ATS) have been used to remove excess amounts of nutrients and heavy metals from mineral wastewaters. ATS are mechanical systems designed for growing algae under controlled conditions to absorb the excess nutrients or/and pollutants from wastewaters.

The wastewater used in this study was mining process wastewater from Talvivaara mining site. The study started with a range finding experiment of wastewater and ten algae species cultivated together. Then ATS testing were done mainly for Zinc and Nickel removal, by it setting-up two replicates and monitoring pH, illumance and measuring metal concentrations in the beginning and at the end of experiment. Lastly a range finding experiment on the Copper tolerance of the ten algae species tested separately was conducted.

The conclusion was that the ten algae species cultivated together in the ATS stabilized the Zinc within 16 days with a removal rate of 99%. The ratio used was the one found optimal in the first range finding experiment, a concentration of 2% pH adjusted mining wastewater respectively. The expected Nickel removal didn’t happen probably because to the air stones used for aeration that most probably leached Ni. The 10 algae species cultivated separately presented variable Cu removal potential.