Biofilm formation at a household drinking water multistage filtration system

The drinking water supply in rural communities needs efficient, appropriate, low-cost, and adaptable technologies to local conditions. This research investigates a household prefiltration system composed of a dynamic gravel filter, a rapid sand filter, and a slow sand filter. This study evaluates the under varying turbidity, organic carbon, and microbial contamination conditions. Kaolin and humic acids were used to simulate natural turbidity and organic matter, while E. coli served as an indicator of microbiological contamination. Analytical methods included turbidity measurement via turbidimeters, total organic carbon (TOC) analysis, and membrane filtration for E. coli quantification. The system was operated to treat between 20 L of water in batch tests and 250 L/day in continuous operation tests. The system was tested over 73 days under continuous operation, with results demonstrating progressive improvements in turbidity and E. coli removal, reaching turbidity removal of 78% and E. coli reduction of 0.9–0.3 log. Additionally, microbial community analysis in biofilms revealed diverse bacterial and protozoan populations contributing to filter maturation. Despite effective turbidity and microbial reduction, additional disinfection steps may be necessary to ensure complete microbiological safety. Overall, the study supports the viability of multistage filtration as a sustainable household water treatment alternative.