Although sitting through a series of talks about water might not be everyone’s idea of a good time, water, particularly clean water is something we all need to survive, and it is something that I have been interested in for a while now. So, my curiosity was naturally piqued at the extremely fortuitous scheduling of two Nerd Nite talks about water. Co-hosted with the MIT Water Club the talks focused on two problems, water desalination and clay pot water filters as an in home water treatment solution.
The first speaker, Leo Banchik opened his talk, “Membrane Desalination: Past, Present, and Future,” with a question, “How much of the Colorado River reaches Mexico?” Alarmingly the answer was none.
Although it is not just physical scarcity that dictates whether or not a community has access to clean water Banchik explained that the people living in that area have a hard time getting enough water, particularly during the devastating drought that was happening at the time.
This left us to ponder, what would be a good way to provide people with more water in an area that is already water scarce? Desalination, which has been around for decades, is one option and it is already used effectively in countries all over the world.
“Desalination in part is a separation process,” Banchik said, “You are basically just separating two things from each other. In this case, salt from water… the two conventional feeds for desalination, the ones you will find most often in the world, are either sea water or brackish water, which is river or ground water”
Considering how many times we’re told not to drink salt water it does seem counterintuitive to try and drink it. But, not I guess, if it’s been through a desalination process.
Banchik explained that desalination happens when the water is put through reverse osmosis which, “involves pushing salty water from one side of a semi-permeable screen to a more diluted side and extracting the salt,” he said. “If you wanted to make this very very salty stream loose it’s water into a dilute side, what we have to do is just push on it… That’s what the piston is for. We push water from the concentrate side into the dilute side.”
Banchik explained that although reverse osmosis is the best option for desalination and can help provide large quantities of drinkable water, there is a flaw. Unfortunately, because it requires a lot of energy to power the reverse osmosis process, it is very effective but also very expensive to use.
As he brought his talk to an end he went on to explain more details about reverse osmosis plants and how they work. His talk included diagrams and questions shouted out from the inquisitive audience, and he even went on to talk about the future of desalination systems and how improvements in technology can affect the efficiency of the process.
While the first talk leaned towards large scale solutions for water treatment the second talk, “Ceramic Water Filter Design for Developing Countries” by Amelia Servi took a more localized approach.
Water treatment in rural areas, is a particularly difficult problem to solve. Servi explained that there are different factors that can affect whether or not water can be brought water in. Piping water in can be difficult and expensive, boreholes and wells can be contaminated, and the ground can be hard to dig in. This leaves in home treatment as the solution. “Household water treatment is when you get whatever water into your household…,” Servi said, “then you have some type of treatment option in your household that you can use to treat it.”
With only two main ingredients, clay powder and rice husks, ceramic pot filters sounded pretty simple. “It [the ceramic pot] sits inside a container and then you put water into the pot and it flows through the walls of the filter into the bottom of the container,” Servi said, “…this filter removes dirt, protozoa and bacteria, but it doesn’t remove viruses heavy metals, or salts…”
As with many things that seem simple, looks can be deceiving. ” Normal ceramic, when you fire it the ceramic sets and you get a pot. But when you have rice husk mixed in, the rice husk combusts so you get little holes in the ceramic where the rice husk used to be,” Servi said. “So this is a very very inexpensive way of making porous ceramic that then can be used for water filtration… the only last step is to paint it with silver, and you might be thinking silver is a very expensive element, it is… but in very small quantities it’s a great biocide and it can add an extra level of protection against biological contaminants.”
Invented in 1981 Ceramic Pot Filters have been around for a while. “There’s an NGO called Potters for Peace which got real into them in 1998. and started promoting them all around the world,” said Servi,”…and it’s an open source design which means that anyone can start up a factory.”
Filters can range in size and composition depending on where they’re made and what is available to add to the clay mixture, which can change from day to day. Servi explained that this can make consistency in filter production and therefore water output a problem. She explained the areas of study focus on things like performance in the field, manufacturing variables and the internal structure of the filters themselves. This in turn helps them understand product appeal and how changes in design and materials can affect performance.
The talks were thought provoking and informative, and it was interesting to hear about two things that are being worked on to improve access to clean water in areas that don’t have it. As the evening came to a close, I had more questions than answers. Eventually, curiosity led me to the WHO website and the UN Water website both which had been mentioned in the talk as good resources.
Lack of access to clean water is probably one of the biggest problems facing the world today. But, living in an area where we water our lawns and wash our cars, access, cost and quality aren’t really an issue and its easy to take it for granted. Even if I wasn’t already kind of curious about our water situation or “poovolutions” and global post apocalyptic dystopias, it would be hard for me not to think about it. As I continue to learn about how challenging it is to bring clean water to the areas and the people that need it, I think our complicated relationship with water, and it’s scarcity, will continue to fascinate me.