Strategies for the sustainable management of industrial wastewater. Determination of the chemical dynamics of a cascade series of five newly constructed ponds

The Portland Aluminium smelter, located near the town of Portland, Australi a, currently discharges over 715 ML of wastewater into the ocean each year. As an alternative to ocean discharge, Portland Aluminium has constructed a number of trial evaporation ponds to receive this wastewater. These ponds must not only be efficient evaporative pans, they must not pollute nearby w etlands, and also be aesthetically pleasing. Hence, water quality is a majo r issue. In this study, a comparison was made between the concentrations of fluoride (F-), sulphate (SO42-), sodium (Na+, potassium (K+), calcium (Ca2 +), magnesium (Mg2+), and chloride (Cl-) ions in the ponds. Our results sho w that there was a correlated increase in fluoride, sodium, potassium, chlo ride, magnesium and sulphate concentrations in April and May 1998 in the co nstructed ponds, followed by a significant reduction in ion concentration b y July 1998 (p < 0.001). Calcium ion was the only ionic species to not beha ve in this manner. Statistically there was no significant change in calcium concentration over time in the constructed ponds (p > 0.05). (C) 2000 Else vier Science Ltd. All rights reserved.