Welcome!
My partner and I would like to start the blog by explaining its purpose: to walk you through our senior design project. As civil engineering students at Santa Clara University, we are required to undertake a large-scale senior design project in our area of interest in order to graduate. We are supposed to dedicate 300-400 hours of our senior year to the project...so, it's kind of a big deal. Also, we wanted to allow people to follow our design process and learn a little bit about some of the common problems experienced by the developing world with regards to water sanitation and purification.
Topic: Improving Current Water Filtration Techniques with the use of Granular Activated Charcoal (GAC, also known as Activated Carbon)
Activated Carbon Filters are similar to the Brita/PUR water filters that many people use everyday. For us, they remove many of the secondary contaminants in the water. You know...we want to make it taste or smell better than tap water. However, it can be a powerful tool in the developing world for removing soluble organic compounds (including commonly used pesticides), as well as improving the taste, smell, and clarity of the water. The biggest problem is: how can we make good quality activated carbon without the same types of materials available in the U.S. That is, we need to maintain a high removal efficiency of the carbon and create a charcoal that will last a decent amount of time without having to be replaced relatively often...using matches, barrels, dirt, and raw organic materials. In the United States, activated carbon goes through a multi-step process including controlled starved-oxygen combustion (See pyrolysis), chemical washing and purity testing. In Nicaragua, we just do not have those types of luxuries. Hence the senior design project!
We are working closely with an NPO called blueEnergy Group. They have established a base along the eastern coast of Nicaragua, in a region called Bluefields. We are focusing our design project on the rural communities in the outskirts of Bluefields. Many of the people get their water from local streams, which unfortunately is downstream of large agricultural areas. Pesticides are commonly present and can cause health problems. blueEnergy has installed Biosand filters in many of the homes in the surrounding areas as well as in Bluefields (Learn more about Biosand Filters). They remove many of the biological contaminants in the water such as bacteria and protozoa, as well as much of the large particulate matter in the water. They do not however, remove the pesticides present in the water sources. Chlorination is also a necessary step in purification of the water, but it must be done after being put through the Biosand filter, because it will destroy the effectiveness of the "bio-layer." The villagers in the communities dislike the taste of the water after chlorination and are therefore less likely to use the chlorine tablets they receive. Using an activated carbon filter prior to Biosand filtration would allow the communities to disinfect the water first using chlorination, then passing the chlorinated water through the activated carbon filter which would take out the excess chlorine as well as the pesticides, THEN running the water through the Biosand filter.
Three Step Purification Process:
1. Chlorination/Disinfection: Removes fecal coliforms and other bad bacteria
2. Activated Carbon Filter: Removes Chlorine and Pesticides (as well as other things)
3. Biosand Filtration
After that...Pure Water!!
Anyway, that's our project in a nutshell. More updates/specifics to come. Please feel free to ask questions!
Mikell & Ami
