Performance study of biosand filter

Abstract

Clean drinking water is a necessity and recycling storm water and grey water has been more appealing in the recent decades to provide filtered water for drinking water and non-drinking water purposes. Biosand filters (BSF) have been a popular filtering system of filtering potable water in developing countries, due to their simplicity in construction, reliability in operation and availability of constituent materials. The BSF removes contaminants from water using four methods: mechanical trapping, predation, adsorption and natural death. The mechanical trapping mechanism occurs when solids and microbes suspended in the water are trapped in the small spaces between sand grains. Pathogens and suspended solids are removed through a combination of biological and physical processes that take place in the biofilm layer and within the sand layer.The aim of the study was to investigate the performance of Bio-sand filter (BSF) prepared with locally available materials in removing contaminants from surface water. The BSF was prepared with sand, gravel and plastic materials.The filter was constructed with specific grain size of sand and gravel; and the operation flow rate was 5.35ml/s. For laboratory analysis 27 water samples were collected from inlet water tank and outlet pipe at different day’s interval. The collected water samples were analyzed for pH, turbidity, total dissolve solids (TDS), Chloride (Cl), Hardness and fecal coliform (FC). The filter was highly efficient in turbidity reduction (85.24% average). The average TDS and EC removal efficiency was relatively low. This system was also highly efficient in fecal coliform reduction. It was concluded that BSF was suitable for removing contaminants from surface water and meet drinking water demand for the people who drink contaminated pond water. The device was made using locally available materials (plastic bucket, sand and gravel). Overall study results revealed a greater portion of turbidity reduction in the filtrate. The filter was found to reduce fecal coliform, though it is not capable of consistently meeting the IS guideline fecal coliform. Keywords: Bio-sand Filter, Coliform Bacteria, Local Resource, Turbidity, Water Purification, Diarrhea, Household water treatment, Wash, Low-Cost Water Supply, Public Health