Use of cattails in treating wastewater from a Pb/Zn mine

Wastewater from a lead/zinc mine was treated by a combined system incorporating a stabilization pond and an aquatic macrophyte system using cattails (Typha latifolia Linn.) as the predominant species. The most dominant plant species growing in the combined treatment system had varying abilities to absorb and accumulate the heavy metals. Paspalum conjugatum contained the highest concentration and Phragmites communis the lowest. Wastewater pH changed from 7.1 to 6.4, COD was reduced 6-fold, dissolved oxygen increased 3-fold and total suspended solids reduced over 99 per cent. Influent levels of lead (1.6 mg per litre), zinc (1.9 mg per litre) and cadmium (0.022 mg per litre) decreased 95, 88 and 87 per cent, respectively.