Development of down-flow hanging sponge – slow sand filter system as water purification system: Infection risk reduction in an East Africa rural area

Abstract

Worldwide, many people still drink unpurified water, putting them at risk of contracting waterborne diseases such as diarrhea. In this study, an interview survey was conducted to evaluate the infection risk from the current water supply in rural areas in Kenya. According to the interview, the residents living in areas with no public water supply drink water from various sources such as surface water, spring water, dug well, rainwater, tap water, and water sold by nearby non-governmental organizations. Further, most of the respondents usually drink unpurified water, which generated a high infection risk value of 0.77 owing to inadequate water storage management. A new self-sustaining water purification process, which is a combination of a down-flow hanging sponge (DHS) reactor kind of biological trickling filter and a slow sand filter (SSF) with a 500 W solar was installed in an area with no public electricity and water supply. The DHS-SSF system efficiently decreased the total organic carbon, color, and turbidity by over 80% after the two-week operation, and the treated water could be used for household water. In addition, a survey for infection risk evaluation was conducted to determine the utility of the DHS-SSF system. However, drinking water supplied by the DHS-SSF system could reduce the infection risk of diarrhea by up to 99.5%. This result indicates that the DHS-SSF system could be an appropriate water purification system in no public water supply area.