Conventional Filtration

Filtration is a part of the water treatment process in which colloidal and suspended material are removed from water by passing through layers of porous media like sand, foam, or fabric. After a while, these dirt materials build up in or on the surface of the media, so the filter needs to be cleaned. This is usually done through backwashing, sending clean water backwards through the filter medium to dislodge particles. Here are two examples of conventional filtration plants in Honduras:

Santa Rosa Water Filtration Plant

San Pedro de Tutule FIME Plant

Both of these filtration systems are powered by gravity, which is something AguaClara strives for as well. The San Pedro de Tutule FIME plant's filtration system has gardens around it, giving it a pleasant look, which might make it more welcoming to the community.

One disadvantage of both the plants is that they are open to the air, so debris could land in them, counteracting any treatment prior to the filtering stage. The Tutule FIME plant also takes up a lot of space. We are designing our whole filtration system, including the filters and clearwell, to be about the size of two of their round filters. We want to keep our system small so that a minimal amount of materials are required, keeping the price down.

One problem we observed with the Santa Rosa system is that it has eight filters, and to backwash one filter, it uses all the other seven. That means they waste a lot of water backwashing that they could be distributing. Also, during backwashing, all of the water that gets filtered goes towards backwashing, so production of clean water is stopped. Backwashing only takes about ten minutes per filter, but with eight filters, it adds up to a lot of time and water spent backwashing.

Many filtration systems have features that AguaClara cannot copy, such as the use of electricity, having parts invisible to the operator, and parts that are expensive or difficult to obtain in Honduras. These two sites have found solutions to many of the problems, but the AguaClara filtration aims to achieve even more. We are looking at foam and stacked filtration, trying to filter and backwash completely by gravity with minimal loss of water to backwashing. We will have our filtration system covered so that no debris can land in it, but the system will also be open to the operator so he or she has a handle on the plant's operations. Lastly, we are keeping the size minimal to ensure that the system is affordable.