Foam Filtration as a Versatile Water Treatment System

This past January members of the Foam Filtration team were part of the student engineering in context trip to Honduras. While there, they were able to implement the first foam filtration system in the field. Despite difficulties getting the system set up for its first presentation (involving inclement weather and putting together the heavy equipment while on the side of a cliff) the team was ultimately able to get the foam filter set up. At first the filter was not working, but after increasing the chemical coagulant dosage to 8 times what they used in lab, the system returned water at 1.87 NTUs, well below the World Health Organization standard of 3 NTUs, where NTU is a measure of turbidity. The video below shows their reaction as the filter started to work.

The idea behind the Foam Filtration team’s research is to run contaminated water through pieces of foam designed with specific densities of pores (porosity) and a chemical coagulant that will cause pathogenic material in the water to solidify into clumps. These clumps of matter will get caught in the pores while the clean, low turbidity water is allowed to pass through the foam. Originally, the team had considered developing the foam filtration system as an add-on at the end of the plant designed to supplement the Sand Filters currently used in the AguaClara Treatment process. However, the team realized that this may not capitalize on the full potential of foam filtration and now the team is focused on designing the system to work as a smaller, isolated system that can be used as a stand alone water treatment method. This type of system could be implemented as a point of use water treatment method for individual homes or small communities, or as an emergency backup in case of crises such as a natural disaster or if something were to happen to a region’s larger treatment facility.

The goal of the team this semester has been to refine the foam filtration system to be an all inclusive system that is both efficient and easy to set up, while also being practical and cost efficient. The vision for this system involves creating a system of packaging using a 55 gallon drum to hold all of the parts needed for the foam filter so that it can be shipped fairly easily. The parts would be packaged in such a way that putting the components of the filter together would be very simple and versatile, and the drum would act as the main body of the filter. This design would allow for quick and consistent access to clean water, as long as there is a source of water.

The trip to Honduras illuminated some aspects of the foam filtration system that were slightly flawed or needed to be rethought. The team is currently working on redesigning some of these features, such as the compression unit the filter uses. The team quickly realized when they were assembling the filter in the field that the compression unit, which could hold a car, is way over designed and made the filter unnecessarily heavy and difficult to put together. They also realized that the chemical coagulant is highly more effective with the idealized mixture of tap water and clay used in lab than with the actual water sources used in Honduras, which have greater levels of biological matter and contaminants. They also found their current method of removing water off the top of the filter was unrealistic and some of the parts were rusted which made the unit difficult to assemble. Along with the maintenance realizations, the team also got to experience first hand what their research could do in the field, and what it’s actually like at the plants using the technology they’ve helped develop. The team members are using all of this to help fuel them this semester as they continue their research to improve the technology so it can be optimally utilized wherever it may be needed in the future.