Reductions of E.coli, MS2 and PRD-1 increases as filtration rate declines. Biosand filters using crushed granite as the filtration media has superior virus reductions than using Accusand silica as the filtration media, only when the media is not backwashed. E. coli reduction did not differ significantly between the two types of filter media.
This study developed a low-cost and accurate method for field enumeration of Vibrio cholerae. Additionally, the removal efficiency of V. cholerae and coliform bacteria using biosand filtration was evaluated. Results indicate that coliform removal efficiency generally exceeded V. cholerae removal, thus highlighting the importance of conducting pathogen specific tests rather than relying completely on indicator organisms.
This study investigated the effect of grain size, hydraulic loading rate, batch residence time, and diffuser design on the performance of the CAWST biosand filter. Coarser grain size reduced bacterial removal efficiency. Longer residence time, on the other hand, improved bacteria removal. In terms of diffuser design, smaller holes and tighter spacing reduced bacterial removal efficiency.
Virus removal in V10 BSFs was greater than 99.99% after only 43 days of operation. Important factors included length of residence time, filter depth, and filter ripening, with the schmutzdecke playing an important role. Diverse microbial communities were found throughout the filter depth.
Using a biosand filter project by DHAN Foundation in India as a case study, this computer model outlines how an NGO can choose effective programme implementation strategies to increase the adoption and consistent use of household water treatment technologies in consideration of complex system interactions, trade-offs, and counter-intuitive outcomes.