Abstract: Away back in 1953 few people in the world, let alone South Africa, knew or had heard about membrane desalination, but there was an increasing awareness that electrodialysis had considerable potential for the desalination of brackish water.In South Africa the development of the new gold fields in the northern Orange Free State and the problems posed by the presence of excessive volumes of very saline mine waters stimulated interest in desalination and the CSIR* in collaboration with the mining industry became involved in the development of the electrodialysis process. By 1959 the largest brackish desalination plant in the world had been built and commissioned. South Africans were thus in the forefront of this technology, even to the extent of making the required membranes locally.Our historical review of membrane development and the applications of membrane technology in Southern Africa encompasses both pressure- and voltage-driven processes. Examples of the pressure processes are microfiltration, ultrafiltration and charged membrane ultrafiltration or nanofiltration, and finally reverse osmosis with fixed and dynamically formed membranes. The voltage-drive processes considered are electrodialysis and electrodialysis reversal.

Abstract: Ironstone mine spoil leaves a legacy of land contamination and diffuse water pollution with acidic, metal-rich drainage. Reclamation for woodland may exacerbate water pollution due to spoil amendment and disturbance. Constructed wetland systems (CWS) are increasingly used for treating acid mine drainage but their performance is poorly understood. A combined approach was used to reclaim the Benhar ironstone spoil heap in Central Scotland. Trees have been planted in spoil treated with dried pelleted sewage sludge, limestone and peat. Spoil drainage (pH 2.7, 247 mg l-1 total Fe) passes through a CWS. Spoil throughflow, surface water chemistry and CWS performance were monitored for 12 months after reclamation. Acidity, Fe, Mn and Al concentrations declined in throughflow after reclamation, although this effect was not uniform. Soluble reactive P has been mobilised from the sewage sludge in residual areas of spoil acidity, but losses of other nutrients were short-lived. The CWS removes on average 33 % and 20-40 % of acidity and metal inputs but removal rates decrease in winter. Spoil reclamation has been successful in enabling vegetation establishment but has also increased Fe and Mn concentrations in surface drainage from the site, even after passage through the CWS.