Solar Sanitation Systems are Changing Developing Countries

The National Collegiate Inventors and Innovators Alliance (NCIIA) combined with the support of the Lemelson Foundation provides $1.5 million to student and faculty programs and ventures annually. Today's featured project by the Georgia Tech Research Institute partnership with the Emory University Center for Global Safe Water, is a much new and improved version of the old outhouse that has been built especially for developing nations and their sanitation problems.

So far this system has been field tested in areas of Bolivia with great success. What the system does is heat the waste through a solar unit that is able to produce temperatures in excess of 50 degrees Celsius (140 F). This is enough heat to destroy most disease causing micro-organisms and bacteria within the waste. The addition of lime or ash is added to increase pH to promote microbial inactivation. Once the waste is rendered harmless within a few weeks, it can then be used as a fertilizer for various crops.

The main objectives of their research was to:

1. Conduct basic engineering and clinical research to further evaluate the field performance of initial prototype systems (temperature, pH and heating times needed for microbial inactivation).

2. Construct and field test advanced prototypes in Bolivia.

3. Establish micro-financing and NGO partners for rapid and scalable use of the technology.

We spoke with Professor Kevin Caravati and Marco Velasco, the student who led the teams efforts in Bolivia, to find out more about how the system works:

Tell us more about the solar sanitation system project.

Kevin Caravati: It started in 2006 with the folks of Emory University who had been doing some work with the Centers of Disease Control down in El Salvador. It was a solar sanitation system. The folks at Emory told us a problem they were facing. People were trying to heat human feces and it was not working well. They were measuring very high incidences of parasitic infection rates in the community. They posed a simple question to us. Can we design a better sanitation system? We looked at it as engineers when we first saw it and said yes, we think we can.

We offered them a couple different projects, and they liked the solar sanitation latrine. They picked it up and built a few prototypes for us here in Atlanta. We learned an awful lot about human waste along the way that we really hadn't thought about much before. Such as how people that live in developing nations have to deal with their own sanitation. The folks at Emory told us they had some work and funding to do down in Bolivia and if we'd like to join them. We put together a team of students from our Engineers Without Borders Program. There were four students, another researcher, and myself who went down with Dr. Christine Moe, from Emory.

They looked at our first several designs and said they weren't going to work. But idea number five looked good. In 2008, we had two students from Georgia Tech, Marco being one of them, and three students from Emory spend 10 weeks in Bolivia working with the community. What Marco did was work with the engineers and builders in four different areas, building more of these systems and collected data. We have left those down there and have continued to collect data from them.

Marco is now working on a report that summarizes all of his work down there. What we are trying to do is mimic what we have done down in Bolivia in the laboratory (here at the university) to make a system we think is going to be sustainable and effective for them. The idea is to build a micro-enterprise around this business, combining the efforts of both Emory and Georgia Tech.

What are the problems with the current sanitation systems in Bolivia?

KC: Of the world's 6.5 billion people, about 2.5 do not have access to adequate sanitation. Essentially what that means is they do not have a hole to do their business in. There is a lot of open defecation. What happens is diseases are transmitted this way. Diarrheal disease kills about 2 million people a year around the world. The real problem is human waste getting into food and water supplies, but also be transferred through insects, flies, mosquitoes, and airborne transmission. What we have is a large segment of the worlds population, particularly about 90 percent of the children under the age of five, who are impacted by this.

The current focus seems to be on bringing clean water to these people, but the root cause of the water being dirty in many cases is human waste found in it. In many countries water is expensive, and it is just far too valuable to be putting human waste in. In these areas what people spend on water can be upwards of twenty-five to thirty percent of their household income. So what we really are striving for, is a way to do sanitation without water. If we can heat human waste to a high enough temperature, roughly 70 degrees Celsius, you are going to destroy those disease causing organisms, pathogens. If you can do that, then people can safely use that material. They can mix it with soil, use it as fertilizer for biofuel crops, etc.

When we first went to Bolivia, the people told us that if we are going to do something, it has to improve the lives of the children, otherwise the community is not going to accept it. First and foremost it has to be attractive to women. The way you do that, is to tell them that it is going to help the lives of their babies, otherwise they do not get engaged. So we worked with women in the Bolivia community to come up with a design that was user friendly to them, which includes being clean, attractive, low maintenance, and effective.

What the NCIIA grant has allowed us to do is replicate some of the things we have done in Bolivia, here in our laboratory, so that we can go back to Bolivia with a durable technology that we think is going to work well for them. We also want to have a business model and a marketing strategy to help this proliferate. One of the challenges in Bolivia is that that the some of the recent relations with the United States has not been as congenial as we would like. They have also had some election violence, so that has somewhat hindered our efforts. Bolivia is the least developed nation in South America. It is also one with incredible natural resources, so its potential is terrific.

How does the solar sanitation system work?

Marco Velasco: The design we came up with is a two chamber design where one chamber is used by the family or the community, and there is a second chamber that is the solar chamber, or oven section. Picture an outhouse with a smaller structure off to the side, where the solar chamber exists. What we've designed these to do, is have the chambers changed out (swapped) every three months. When that happens, you switch the chamber that was being filled with the solar chamber on the outside, dumping the old, harmless waste and placing it back inside the toilet to be re-filled. Solar energy is then passed into the chamber (with the fresh waste), and generates enough heat to kill the pathogens. Any of the people I worked with who viewed the end result were impressed. They loved the design. It was very warmly received.

Essentially it is like a brick roasting oven, except we are just roasting something different (laughs). To get down to the knitty-gritty, human waste is about 75 to 85 percent water. For this system, we have a urine separation plate in the front that is drained away to a small gallon sized tank. Urine is basically harmless, but the important thing here, is the urine is separate from the waste. That way it dries out quicker when heated and it also drops the odor problem significantly. If you can reduce the stench and odors, it also reduces the amount of flies and insects. It helps improve air and water quality, while also improving health because you are reducing the risk of disease transmission. There are several different factors at work here.

Does the system have a name?

KC: We call it the SunSeat.

Is there anything from this research you've learned that pertains to a modern society?

MV: Think about if in this country we were paying Bolivia's premium for water. You would be talking about maybe $10 to $15 every time you use the toilet. When you are talking about that kind of money to use the bathroom, imagine what kind of strain that would put on your community.

Is there a way for our readers to get involved in this project?

KC: We are trying to promote a technology to address a problem that nobody wants to discuss and that is a challenge. The big thing that impacts us most is the ability to get to Bolivia and find the funding for students to dedicate themselves to work on the project here in the US. Donations would certainly help. If you're telling people that it is okay to use the waste for their crops, you want to make sure that is safe, and we have not been able to do extensive testing on it from that perspective.

Establishing the micro-enterprise business when we do not have people there a good six months out of the year, is also a challenge. We've talked to funding institutions, and they have told us that if we are going to build a micro-enterprise, to get the technology transferred and people trained, we really need to have people on the ground working with them on a dedicated basis.

Marco, what would you say this experience has been like?

MV: It really was a life changing experience to be entrusted with a project I feel is this important. Working on this project was so significant for me because I was given the freedom and trust to make some changes I felt were necessary for the success of the project. It is not so common for students to be shown that kind of trust in something so important, I am grateful to have been given that opportunity.

Interestingly, one of the other students who worked on this project in its early stages, was none other than Calvin Johnson of the Detroit Lions. He went from the "outhouse to the penthouse," as Kevin told us. Thank you both Kevin and Marcos for sharing your project with us. I doubt most of us will ever look at an outhouse the same way again...