Design and Optimization of Sedimentation Tank Coupled with Inclined Plate Settlers as a Pre-Treatment for Ultra-Filtration

Abstract

Access to clean and safe drinking water is difficult in most rural areas of Sub-Saharan Africa. In most places, the water is generally available during the rainy season, but it is muddy and full of sediments. But in Karatu, regardless of the season, the water is always highly turbid with suspended particles. High turbidity water is a great challenge to water treatment works as it can be hard to remove and also harbors pathogens. Because of a lack of cost-effective purifying agents, communities suffer from water scarcity or indeed drink water that is no doubt contaminated by sediment and livestock/human feces. Unsafe drinking water is a major cause of water-related diseases that predominantly affect people living in developing countries. Today there are many technologies available to treat unsafe water. However, most of such technologies are suited for use with low turbidity source water. Ultra- Filtration (UF) is one technology which is limited to treating high turbidity water. The pre-treatment of high turbidity water (>1000 NTU) is a challenge that was investigated in this research. This paper describes a laboratory scale sedimentation tank coupled with Inclined Plate Settlers (IPS) tested and optimized at Nelson Mandela African Institution of Science and Technology (NM-AIST), to see if, given the local particle sizes and distribution in the earthen dam water of Karatu, IPS can pre-treat the raw water to remove enough turbidity to make UF a feasible option. The results of this work show that IPS is not only a feasible option in pre-treating highly turbid water for the UF (˂ 50 NTU) but also a viable technology in treating water with very high turbidities to within the Tanzania drinking water standards (< 25 NTU).

Keywords: High turbidity water; Sedimentation tank; Inclined Plate Settler; Ultra-Filtration; Water supply