Water, Sewage & Effluent May-June 2017 - Page 22

Understanding the need for water reuse This continuation of the National Water Resource Strategy 2 looks at the key drivers that affect water reuse choices. By the Department of Water and Sanitation F ive key considerations affect the choices related to water reuse as an option for water supply and augmentation: • Water quality and security of supply • Water treatment technology • Cost relative to other water supply alternatives • Social and cultural perceptions • Environmental considerations. The wastewater and effluent treatment technologies for reuse applications are generally proven for South African conditions. A local knowledge base exists to plan, design, construct, operate and maintain a wide range of treatment technologies. However, some of the more sophisticated technologies, such as advanced oxidation and membrane desalination, have been applied to a limited number of local projects. The South African water industry will need to grow capacity to confidently implement some of the more advanced water reuse technologies. Cost considerations Table 2: Applicable water treatment technologies for water reuse. 20 Water Sewage & Effluent May/June 2017 Where water reuse is more cost- effective compared to other alternatives (such as reducing water requirements, securing a fresh water supply, or desalinating seawater), then water reuse becomes an attractive choice, provided that the quality of water can meet the necessary requirements and there are no important cultural or social objections to the use of this water. Costs are affected primarily by water quality requirements (related to both supply and discharge, and the associated treatment requirements) and the relative geographical locations of water supply and needs. As supply costs increase and with the introduction of waste discharge charges, the cost