Foam and Bag Filtration
Currently, the effluent water from an AguaClara plant has a turbidity of about 5 NTU. Our goal is to reduce the effluent turbidity to less than 1 NTU. One potential method of accomplishing this is adding a filtration unit to the AguaClara plants.
Numerous techniques of water filtration are in use today, most of which involve the use of sand as the porous media. Our team is interested in investigating the filtering capacity of a polyurethane foam material as opposed to the traditional sand method. With proper implementation, a foam filter could reduce the amount of water that is wasted during the backwash cycle of a traditional sand filter. A foam filter could also potentially require less area, and be less expensive to build than a traditional sand filter.
With these advantages in mind, we have considered a number of different designs which could provide the desired standard of 1 NTU effluent water turbidity.
Flat Foam Sheet Experiments
Prior to considering the actual design of a proposed filtration unit, it is necessary to know the actual filtering capacity of the foam material we would like to use. Therefore, a number of experimental trials on foam with vary pore sizes and flow rates were conducted. Briefly, it was found that the flat foam sheets alone do not provide enough colloid removal, under the conditions tested, to be an implementable method of filtration for the AguaClara plants. However, under more realistic conditions, rather than the worst case lab conditions as tested, foam filtration may in fact be feasible. Please see the results and discussion of each experiment for further explanation.
Foam Media Upflow Design
An alternative to using the foam simply as a flat sheet which water is filtered through is to design a hybrid upflow filter, which uses small pieces of the foam as the filtering material, as opposed to the traditional upflow sand filter. This idea is based on the technique outlined in this article:
//www.wioa.org.au/conference_papers/06_vic/documents/StewartShipard.pdf
- Research has not yet been conducted for this design. Will update as further research is conducted.