Macroalgae are a productive resource that can be cultured in metal-contaminated waste water for
bioremediation but there have been no demonstrations of this biotechnology integrated with industry.
Coal-fired power production is a water-limited industry that requires novel approaches to waste water
treatment and recycling. In this study, a freshwater macroalga (genus Oedogonium) was cultivated in
contaminated ash water amended with flue gas (containing 20% CO2) at an Australian coal-fired power
station. The continuous process of macroalgal growth and intracellular metal sequestration reduced the
concentrations of all metals in the treated ash water. Predictive modelling shows that the power station
could feasibly achieve zero discharge of most regulated metals (Al, As, Cd, Cr, Cu, Ni, and Zn) in waste
water by using the ash water dam for bioremediation with algal cultivation ponds rather than storage of
ash water. Slow pyrolysis of the cultivated algae immobilised the accumulated metals in a recalcitrant Crich
biochar. While the algal biochar had higher total metal concentrations than the algae feedstock, the
biochar had very low concentrations of leachable metals and therefore has potential for use as an
ameliorant for low-fertility soils. This study demonstrates a bioremediation technology at a large scale
for a water-limited industry that could be implemented at new or existing power stations, or during the
decommissioning of older power stations.