Evaluation of the management strategies of mine wastewater in West Rand area, Gauteng province in South Africa

Abstract

This study was undertaken to assess the “effectiveness” of acid mine drainage (AMD) mitigation and management strategies in the West Rand region, Gauteng, South Africa. It involved the determination of water quality at selected points along Twelopiespruit stream. The water quality data was analysed using Microsoft Excel and Geographical Information System (GIS) modelling technique to determine river water quality against the regulatory wastewater standards and legal framework. The findings showed that Fe (II) was reduced from a high concentration of 490 mg/L from Winze 18 to 9.57mg/L at the discharge point (Pit), which is an over 95% removal of Fe (II) from the AMD. Water from Winze 18 shaft was acidic and was treated to raise the pH to between 8 and 10 leading to the precipitation of metal hydroxides and oxides. Sulphate concentrations at the discharge point were as high as 2700 mg/L against the DWS sulphate effluent limit of 600 mg/L. High concentrations of sulphates at the discharge point clearly showed that water treatment technologies within the study area were unable to lower the sulphates levels to meet the regulatory sulphate standards in the effluent. Further, findings revealed that current legal and policy factors do not promote uncompromising control measures to the mines in addressing the detrimental impact of AMD. Thus, alternative ways to remediate AMD, particularly options that remediate high concentration of sulphates, were recommended.