Optimization of Sedimentation Tank Coupled with Inclined Plate Settlers as a Pre-treatment for High Turbidity Water

Abstract

Access to clean and safe drinking water is a challenge in most rural areas of Tanzania. Unsafe drinking water is a major cause of water-related diseases that predominantly affect people living in developing countries. In most places, water is readily available during the rainy season, but it is muddy and full of sediments. But in Karatu, regardless of the season, 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 and use water that is no doubt contaminated by sediment and livestock/human feces. Today there are many technologies available to treat unsafe water. However, most of such technologies are suited for use with low or no turbidity source water. Ultra- Filtration (UF) is very effective in making unsafe water safe through removal of chemical species and pathogens. UF, however, like many other treatment techniques, is limited to treating water with high turbidity. Pre-treatment is needed. 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 NM-AIST, to see if 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). The design is ready for pilot testing in field environment.