Conductivity as an indicator of surface water quality in the proximity of ferrochrome smelters in South Africa

Abstract

South Africa is one of the leading ferrochrome (FeCr) producing countries. One of the main environmental and healthrelated issues associated with FeCr production is the possible generation of Cr(VI). However, Cr(VI) is not the only potential pollutant that has to be considered during FeCr production. Various water-soluble species are present in FeCr waste materials and in process water. Considering the size of the South African FeCr industry and its global importance, it is essential to assess the extent of potential surface water pollution in the proximity of FeCr smelters by such watersoluble species. In this study water conductivity was measured as a proxy of general water quality. Although deposition was not measured, comparison of surface water results indicated that atmospheric deposition of pollutants originating from FeCr smelting did not significantly impact surface water quality, but that surface run-off and/or groundwater leaching were the main contributors. At two FeCr smelters it was observed that these smelters did not impact surface water quality negatively. In contrast, surface water pollution originating from at least four FeCr smelters was apparent. However, only at one smelter did pollution result in surface water conductivity that indicated a water quality not fit for human consumption. No correlations could be made between potable water quality and possible pollution from FeCr smelters. Notwithstanding this limitation, it was found that potable water sampled at all sites complied with the conductivity criteria for human consumption