Ideas at Work Biosand Filter
Ideas at Work
The IaW Round Biosand Filter is no longer in production. However, product price range is known to be $100-200 USD
Membrane filtration systems, Community scale purification systems, Point-of-use filtration equipment, Chlorination and other Biosand Filters
Rural communities and households in Cambodia.
The Round BioSand Filter is manufactured on demand via a mould unit. The main parts of the mould unit are shown in the exploded view below are: 1) the puller, 2) an inner mould, and 3) outer mould.
The mould is bolted together, turned upside down and fitted with a copper outlet pipe. A concrete mix is then poured in the mould and compacted down. After several hours the puller is used to remove the inner mould after which the outer mould can be removed revealing the finished filter shell. The filter is then filled with sand and gravel layers.
No longer available for purchase.
The IaW Round BSF is based on a design by MedAir and has a ‘round’ form instead of a ‘square’ form typical of most BSF units. This is advantageous as it significantly reduces the mass and material costs of the unit. It also makes it easier to move the unit by rolling it on its bottom edge. This is achieved by relatively simple modifications to a standard round cement drain pipe moulds.
To operate the IaW BSF contaminated water is poured into the unit at the top. The water passes through the diffuser plate and the sand and gravel layers. Head pressure pushes water through the copper pipe in the base to the outlet point. Biological contamination is reduced through the actions of adsorption; mechanical filtering, predation (biological layer) and natural die off. The typical flow rate of the unit is around 60 liters/hour.
Dimensions of the finished BSF: Outer diameter: 35cm Inner diameter: 30cm Height: 95cm Weight: 60kg
Users are responsible for maintenance and repair.
This is no longer in production.
The typical flow rate of the unit is around 60 liters/hour.
The Biosand Filter (BSF) is a proven technology, which removes pathogens such as bacteria, protozoa and helminth. BSFs are also somewhat effective for the removal of virus (CAWST 2009). Physical parameters such as turbidity and iron are also eliminated from drinking water. However, dissolved chemicals (such as organic pesticides or arsenic) are not removed. The treated water generally has an agreeable colour, taste and odour. The table below shows the biosand filter treatment efficiency in removing pathogens, turbidity and iron (adapted form CAWST 2009).
Additional BSF evaluations have been aggregated by CAWST and include randomized controlled trials and field studies.
No cited hazards.
Safe water storage.
Significant research has been conducted on BSF technology. A comprehensive list is available via CAWST
Examples include: Biosand filter literature summary – CAWST An Assessment Of Continued Use And Health Impact Of The Concrete Biosand Filter In Bonao, Dominican Republic – American Journal of Tropical Medicine and Hygiene
IaW sites CAWST BSF standards, however standards have not been identified. CAWST does provide a Biosand Filters Knowledge Base intended to guide practitioners with BSF knowledge related to Construction and Installation, Operation and Maintenance, Implementation, Designs and Modifications and Performance
BSF is a field proven and well established technology. BSF evaluations have been aggregated by CAWST and include randomized controlled trials and field studies.
Filtered water can be evaluated against EPA water quality standards. IaW suggests their BSF delivers water meeting these standards.
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