Abstract
Access to sufficient quantities of safe water is not just a public health issue but also a human right. Water pollution causes millions of deaths and illnesses every year. To solve the issue of water pollution at household levels and during emergencies, slow sand filters are suggested as good choices. This study aimed at designing small scale Household Slow Sand Filter (HSSF) with locally available materials. This experimental study was conducted under ambient weather conditions to test efficiency of two proposed filters in removing pollutants from source water. Natural water samples were collected from the Blue Nile, and the White Nile. The two filters were first cleaned up followed by a ripening period of two weeks to allow formation of the Schmutzdecke (the biological layer). Data were subjected to Hierarchical cluster analysis (HCA), ANOVA and Pearson correlation. The current research revealed that, both filters were highly efficient in removing E.coli and total coliform. The average log10 removal of total Coliforms and E Coli for the first filter ranged between 1.9 log and 1.7 log compared to a range of 1.1 log to 1.2 log for the second filter. The association of log10 total coliforms with turbidity and TSS has drastically changed after filtration. Overall, the best performance of filter 1 was reported for removal of bacteria, turbidity, iron (Fe), TSS, K and NO2, and Zn, respectively, versus NO2, Fe and Zn for filter 2, in the same order. The trend of ions removal assumed to be affected by both mineralization and oxidation which further supported by HCA results and it was differ than the pattern of heavy metals removal that was generally moderate not exceeded 65%. All soluble ions after filtration did not exceeded WHO guideline limits. The first proposed filter suggested to be efficient that need to be confirmed by further studies.