The potential of selected macroalgal species for treatment of AMD at different pH ranges in temperate regions

Abstract

The metal bioaccumulation potential of selected macroalgae species as different pH ranges were study for usage as part of a possible secondary passive AMD treatment technology in algae ponds in temperate regions during winter months. . Two separate studies were conducted to determine the suitability of macroalgae for passive treatment when metabolic processes in macrophytes and microrganisms in constructed wetlands decreases due to seasonal changes. In the field study, the bioconcentration of metals (mg/kg dry weight) measured in the macroalgae mats were in the following order: site 1. Oedegonium crassum Al > Fe > Mn > Zn; site 2. Klebsormidium klebsii, Al > Fe > Mn > Zn; site 3. Microspora tumidula, Fe > Al > Mn > Zn and site 4. M. tumidula, Fe > Mn > Al > Z. In the laboratory study, cultured macroalgae K. klebsii, O. crassum and M. tumidula isolated from the field sampling sites were exposed to three different pH values (3, 5 and 7), while bioaccumulation of the metals, Al, Fe, Mn and Zn and glutathione-S-transferase (GST) activity was measured in the different algae species at a constant water temperature of 14 ˚C. . Bioaccumulation of Al was the highest for O. crassum followed by K. klebsii and M. tumidula (p < 0.0001). From the study it was evident that the highest metal bioaccumulation occurred in the macroalgae O. crassum at all three tested pH values under constant low water temperature.