Characterization and pre-treatment of water from the Vaal River

Extensive urbanization, economic development, and industrialization coupled with water wastage are placing increased pressure on the quality of water from the Vaal River system. This research study was carried out to assess the water quality of the Vaal River in terms of physico-chemical parameters and heavy metals concentration. Three (3) locations were identified within the Upper Vaal Water Management Area (WMA) where water samples were collected in the months of July and September 2014. A total of eight water quality parameters namely pH, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Total Hardness (CaCO3), Chemical Oxygen Demand (COD), Nitrate (NO3-), Phosphate (PO43-), Sulphate (SO42-) and Heavy Metals concentration were measured in the laboratory using standard analytical procedures. Values of measured parameters were then compared with the South African water quality guidelines for domestic use and aquatic ecosystems. The findings showed that all the physico-chemical parameters and heavy metals concentration measured were within the tolerable limits except nitrate which exceeded the recommended limit of 6 mg/l, with values ranging from 30-31 mg/l in July and 19-21 mg/l in September. The analytical data also indicated that after pre-treatment of the water sample by filtration and adsorption, the TSS level, TDS concentration, and nitrate content were significantly lowered. Nitrate was reduced to below the acceptable limit after treatment. It was therefore concluded that the river water in the Upper Vaal Water Management Area was not suitable for domestic purposes without any form of treatment and frequent monitoring of physico-chemical parameters is imperative in order to have a full representation of the variations in the water quality