Water management tools as a means of averting a possible water scarcity in South Africa by the year 2025

South Africa, currently categorised as water stressed country is forecasted to experience physical water scarcity by the year 2025 with an annual freshwater availability of less that 1 000 m3 per capita. With the trends in population growth and its attributes and continuous pollution of the available water sources, there is bound to be increased pressure on the available water probably resulting in increased conflict over its allocation and a further stress on this resource leading to scarcity. Most countries in the world including South Africa have developed most of their water resources with very little scope for further expansion. This study attempted to establish possible solutions to this scenario. Possible solutions would be as follows. First is the demand management of the water through developing and or improving existing systems that improve water use efficiency in the various demand sectors thereby increasing access to more users and uses for a given volume of water. Second is identifying and developing alternative supply systems suitable for the various demand sectors in order to augment the conventional supply volumes. Third is the application of feasible, special management techniques to improve water quality to appropriate standards for particular uses in areas where natural poor quality water occurs. Fourth is the reallocation of some water from low benefit uses to higher benefit uses. Fifth is the possibility of water transfer from surplus areas to deficit area. A water management tool/model suitable for the various sectors of demand and suitable areas of application in each sector is envisaged as the output of this study. If found to be practicable, and eventually utilised, this model will have the potential to increase the water availability for the various sectors and avert possible conflicts in water allocation. The impact of this economically, socially and environmentally in South Africa and possible application in other water stressed countries with similar conditions will be significant. Water SA Vol. 30 (5) 2005: pp.120-12

Performance of multistage filtration using different filter media against conventional water treatment systems

This study was aimed at introducing multistage filtration (MSF) (a combination of slow-sand filtration (SSF) and pretreatment system - horizontal flow roughing filter (HRF)) as an alternative water treatment technology to the conventional one. A pilot- plant study was undertaken to achieve this goal. Evaluating the MSF performance vs. the existing conventional system in removing selected physical and chemical drinking water quality parameters together with the biological water quality improvement by the MSF without chemical use was done. Evaluation of the effectiveness of the MSF system utilizing locally available material, i.e. gravel, improved agricultural waste (charcoal maize cobs) and broken burnt bricks as pretreatment filter material was also done The benchmark was the Kenya Bureau of Standards (KEBS) values for the selected parameters. Results showed that with proper design specifications, MSF systems perform better than conventional systems under similar conditions of raw water quality and environmental conditions. The tested locally available materials can also be effectively used as pretreatment media with each allowing a filter run greater than 82 d and therefore could serve as alternatives where natural gravel is not readily available. With special reference to the bacteriological quality improvement, the MSF greatly improved the bacteriological quality of the water recording removal efficiencies of over 99% and 98% respectively for E. coli and total coliforms. Despite the observed performance, MSF should be complemented with chlorination as a final buffer against water-borne diseases. However, in this case, the dosing will be greatly reduced when compared to the conventional system. WaterSA Vol.30 (3) 2004: 361-36