The BioSand Filter™ was
invented to serve the household and smaller communities with emphasis on
its suitability in developing countries. Smaller community uses are now
better served by the Manz Slow Sand Filter™ (MSF). These are mature
technologies which may also augment or create new markets for commercial
operations for corporations doing business in developing countries.
The patent rights to the
BioSand filtration (“BSF”) process are owned by Pure Filtered Water Ltd.
This process patent allows the traditional slow sand water filtration
systems to be stopped and started, thereby providing efficient usage which
was not available before at a household or smaller community level, as the
application for traditional slow sand filters is at a municipal level.
The BSF has the following
features enable it to make a significant contribution especially in
- Removes toxins and pathogens – arsenic, water borne parasites,
bacteria and viruses, iron (and iron bacteria), manganese, fluoride,
sulphur smell and other obnoxious gases, colour, foul taste, toxins,
silt, sediments and algae.
- Easy to use – contaminated water is poured in the top of the filter
and it is in effect collected immediately from the outlet ready for
- Well accepted by end-users – this information is based on third
party interviews of the householders who use the filter in developing
countries; they also state that the water tastes better and they feel
- Affordable – providing safe water through a sustainable low one time
only capital cost.
- Does not require ongoing replacement parts and operates effectively
for at least ten years.
- Allows shifting to and from surface and ground water – due to the
wide range of pathogen, particulate and toxin removal, it enables the
user to seek out the most convenient water source.
- Targeted for household use – easy to clean, removing the complexity
associated with traditional slow sand filtration systems.
- Recent adaptations have been made to enable the use of local low
cost materials in the manufacture of the product.
- Robust technology that does not clog up easily and it is well suited
to the most demanding environments.
There are approximately
300,000 household BioSand Filters™ which have been distributed through 70
countries, mainly in developing countries. Information on a number of the
specific applications to date is available at
How It Works
The filter is filled with
several layers of sterile media specially manufactured from a hard,
impervious uncontaminated media, each of a different degree of fineness.
Contaminated water is poured into the top and emerges from the bottom of
the filter ready for drinking. It is purified by flowing through the
media and by a naturally occurring biological payer that forms on the top
of the media. This is a mature technology based on the same principles as
used widely in large scale municipal slow sand filtration facilities.
The BioSand Filter™
produces consistent quality water after set up and conditioning. The
biological layer on top of the filter grows and collects the various
particulate being removed. The flow becomes impeded over time which may
be the situation in days or many months depending on the quality of the
raw water. When the householder decides the flow is too slow the user may
maintain it. This entails pouring water into filter, agitating that upper
1 cm of sand with the rod and then use a ladle to remove as much of the
water as possible, taking care not to scrape the surface of the sand.
Credentials of the
“New Horizons for Sand Filtration, April 3, 2004” is a definitive paper on
the efficacy of the BSF.
Appendix II “Toxicant and Parasite
Challenge of the Manz Intermittent Slow Sand Filter” provides a study of
the BSF in which Environment Canada participated.
is entitled “University of North Carolina Household Filter Treatment and
Health Research in Cambodia 2005-2007” which studies field results.
Appendix IV University of North Carolina “Evaluation of the
Biosand Filter for Reducing Risks of Diarrheal Illness and Improving
Drinking Water Quality in Communities of The Dominican Republic”.
Appendix V University of North Carolina “Point of Use Household
Drinking Water Filtration: A Practical, Effective Solution for Providing
Sustained Access to Safe Drinking Water in the Developing World” which
compares various alternate technologies used in developing countries.