Optimal Acid Mine Water Treatment Network Design with Multipurpose Evaporation and Irrigation Regenerator Subnetwork

  • Timothy Rukuni Tshwane University of Technology
  • A Kolesnikov Jomo Kenyatta University of Agriculture and Technology
  • MAurice S. Onyango Tshwane University of Technology

Abstract

South Africa is a water strained country. It is speculated on good grounds that the demand for water is already equal to or exceeds the supply. The limited water supplies are frequently contaminated by acid mine water discharges which also poses huge environmental, ecological and health risks where water users are frequently exposed to high metal concentrations. In South Africa, like in other countries in the region, mining started over a century ago and most of the acid mine drainage (AMD) discharge is coming from abandoned mines and this leaves the government to carry the burden to avoid further decants and contamination of the scarce surface and underground water resource. The current estimated cost by the Department of Water & Sanitation for AMD neutralisation and desalination is R3.6 million/(ML/day) and R60 million/(ML/day) respectively. These figures are huge taking into consideration that the total flow in Gauteng province alone is 200 ML/day. By using process integration and its enabling tools, the current study seeks to develop and evaluate a robust integrated acid mine water treatment network with multiple treatment or regeneration units. This allows for selective use of the treated mine water in agriculture, process industries, municipalities for drinking water purposes while simultaneously minimising the environmental impacts and costs. This was achieved by embedding a subnetwork of detailed evaporation and irrigation network linked to a neutralisation, softening and desalination (e.g. reverse osmosis and ion exchange) water treatment network. Based on the network and a fixed flow-rate of 30 ML/day for the Western Basin, a mathematical optimization model will be developed and optimised for optimal flow-rates of acid mine drainage into the treatment units and treated water into the distribution systems (Agriculture, Industry, rivers, environment and municipalities). The results of the preliminary water network development on the neutralisation stage have indicated that the total chemical cost for the neutralisation stage can be reduced from the estimated R3.6 million/(ML/day) to R1.9 million/(ML/day).Keywords—  Acid mine drainage, process integration, desalination, neutralisation.
Published
Sep 26, 2017
How to Cite
RUKUNI, Timothy; KOLESNIKOV, A; ONYANGO, MAurice S.. Optimal Acid Mine Water Treatment Network Design with Multipurpose Evaporation and Irrigation Regenerator Subnetwork. Proceedings of Sustainable Research and Innovation Conference, [S.l.], p. 185-193, sep. 2017. ISSN 2079-6226. Available at: <http://sri.jkuat.ac.ke/ojs/index.php/proceedings/article/view/596>. Date accessed: 24 may 2018.