14 November 2013

Foam Filtration for Smaller Communities

Foam filtration isn’t a new idea but it has been troublesome to implement; unlike a sand filter, running water at a high velocity through the filter column isn't enough to clean the foam filter properly, which poses an inconvenient design constraint.

Otherwise, foam filtration is very effective. The team has, through a series of experiments, discovered that having contaminated water run through a piece of foam with thirty pores per inch (30 PPI) and subsequently through a piece of foam with ninety pores per inch (90 PPI) gave the best results, delivering water quality that exceeds both U.S. EPA and World Health Organization standards. While our stacked rapid sand filter is preferable under most circumstances, the team is seeking other uses for foam filtration.

From left to right: 30 PPI foam and 90 PPI foam
One idea was to implement foam filtration as a point-of-use system designed for personal use instead of community use. However, while the foam filter increases the clarity of the water, it can't effectively deactivate pathogens without the help of a chemical doser. Another idea was to build an emergency water filtration system using the foam filter. While the larger size allows room for the chemical doser, our model ultimately proved too unstable for actual use.

The team's most recent plan considered the fact that while some communities may find it economically feasible to construct and maintain an AguaClara plant, others might not be able to afford it. Foam filtration seems like a good compromise between efficacy and affordability. The team is currently working on designing a system aimed at serving smaller communities, with populations of around a hundred families. Their objective is to find the optimal method for cleaning the foam given the system's larger size. The team will be communicating the results of their work to Agua Para el Pueblo, our partner in Honduras, this coming January.

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