Investigation of the impact of high turbidity feed water on the performance of Gravity Driven Membrane modules

Abstract

Majority of the low-income households in Uganda who use surface water, collect it from ponds, rivers and lakes at turbidity in the range of 60 – 160 NTU. The Gravity Driven Membrane (GDM) is a low-cost water treatment method fully driven by gravity thereby, requiring no electricity for regular back flushing for sustainable operation. This makes the system low-cost. The study evaluated the performance of the GDM filters with raw water of high turbidity. Flux values, turbidity, pH, electrical conductivity, temperature and E. coli were monitored both in the raw water and filtered water. The flux values were observed to be in the range of 5-22L/h/m2. The data collected data indicated a 99% removal of turbidity. A decrease in E. coli from too numerous to count to an average of 7 CFU/100 mL with log removal value of 2-3 was obtained although the treated water indicated high levels of the E. coli strain O157. There was no significant difference between the pH and electrical conductivity of the raw water and filtered water indicating that GDM is not suited for treatment of water with high dissolved solids content. The GDM if used with other treatment methods like chlorination has the potential to be applied for the provision of affordable safe water to rural Ugandans.