BioSand filters operated in continuous and intermittent flows: challenges in the construction, operation and maintenance

Abstract

The biosand filter - BSF has been used for the household treatment of drinking water in poor communities around the world due to its low cost, efficiency and simplicity in operation and maintenance activities. Although its efficiency in removing the physical, chemical and microbiological parameters has been investigated, studies have not considered: i) the challenges in building, regarding the reality of the isolated communities of Brazil; ii) the characterization of the flow in biosand filters (continuous and intermittent flows); iii) the use of natural coagulants as a pre-treatment of the water influent to BSF, especially when the resources show high turbidity, critical microbiological risk and cyanobacteria; and iv) the study of simple techniques for the adsorption and disinfection of the BSF effluent.In this context, this research project aims to i) improve the BSF and simplify its construction; ii) characterize the flow in the biosand filters operated in continuous and intermittent flows; iii) study the performance of the Opuntia ficus-indica and Nopalea cochenillifera cactus as natural coagulants, aimed at the pre-treatment of water influent to the biosand filter; iv) study the performance of the Luffa cylindrica plant as an alternative adsorbent of the BSF effluent and the Hibiscus esculentus and Luffa cylindrica plants as an alternative disinfectant of the biosand filter effluent; v) evaluate the effectiveness of BSF when both pre-treatment (natural coagulants) and post-treatment (adsorbent or disinfectant alternative) are employed in full-scale units and operate in continuous and intermittent flows; and vi) analyze the water quality by toxicity tests and using larvae of Chironomus xanthus.Four BSFs operating in continuous and intermittent flows will be mounted in a Pilot Plant Laboratory in the Department of Hydraulics and Sanitation, at São Carlos School of Engineering, University of São Paulo - DHS/SCSE/USP. The research will be coordinated by the Principal Researcher with the collaboration of Professor PhD. Juliano José Corbi in the toxicological tests. Three Hydraulics and Sanitary Engineering MSc students and three SCSE/USP undergraduate students will also participate in the project. The budget predicted for a two-year research is R$85.285,00.The research will enable knowledge gains regarding the BSF so that it can be implemented in isolated communities in Brazil. The configuration of BSF may be of interest to various sanitation companies that aim at large-scale productions. Several papers will be published in journals and national and international conferences throughout the research period. (AU)