Ideas at Work Biosand Filter
Ideas at Work
Ideas at Work (IaW) distributes Biosand Filters in Cambodia as an effective household water treatment system.
Ideas at Work (IaW) Round Biosand Filter is a product for providing improved quality water to rural communities in Cambodia. Note: this product is no longer in production.
Product no longer available
Membrane filtration systems, Community scale purification systems, Point-of-use filtration equipment, Chlorination and other Biosand Filters
Goal 6: Clean water and sanitation
Rural communities and households in Cambodia.
The Round Bio Sand 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.
Is this filter designed for individual, household, or community use?
Manufacturer-specified flow rate (L/hr)
Laboratory-evaluated log scale removal rate of bacteria
Laboratory-evaluated log scale removal rate of protozoa
Laboratory-evaluated log scale removal rate of viruses
Reduction levels of heavy metals and/or arsenic through this treatment system
Manufacturer-specified maximum level of inlet turbidity (NTU)
Range or value of outlet turbidity levels (NTU)
Recommended treatment capacity between cleanings
Description of materials of construction
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, reducing the mass and material costs of the unit. This design 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 L/hr.
Dimensions of the finished BSF: Outer diameter: 35 cm; Inner diameter: 30 cm; Height: 95 cm; Weight: 60 kg
Users are responsible for maintenance and repair.
This is no longer in production.
The typical flow rate of the unit is around 60 L/hr.
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.
An Assessment Of Continued Use And Health Impact Of The Concrete Biosand Filter In Bonao, Dominican Republic – American Journal of Tropical Medicine and Hygiene
Although Biosand filters are known to reduce pathogen load in drinking water, this technology does not consistently meet WHO requirements.
Evaluation methods for this specific design of Biosand filter has not been evaluated. However, Biosand filters have been evaluated both in field and laboratory settings across the globe.
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