September 2011

This summer the Bill and Melinda Gates Foundation announced a multimillion dollar grant to reinvent the toilet.¹ Most people we know use it every day but don't give much thought to it. I know I didn't used to. Most people through the world, however, (about two thirds in fact) don't even have access to a flush toilet. In developing countries, poor sanitation is the primary cause of disease. My first exposure to unsanitary living conditions came when I visited Belize City, the capital of the small Central American country. Open sewers lined the streets. In addition to the increased risk of diarrhea and illness, the condition also greatly lowers the quality of life and -- what should we call it? -- air quality. I found similar conditions in poor sections of Guatemala, Brazil, and the Philippines on my visits there. Each year 1.8 million people die due to illnesses caused by lack of toilets and sanitation. And 2.6 billion people, mostly in India, Africa and China, have no access at all to sanitary toilets. So, the Gates Foundation decided to spur innovation with their Reinventing the Toilet challenge in an effort to make the world a better and healthier place.

A lot of folks -- aside from Bill Gates and myself -- are thinking about toilets. There's a World Toilet Organization (http://worldtoilet.org/wto/) which holds an annual World Toilet Summit.² There's even a World Toilet Day (19-Nov). There seems to be a desire to make toilets that use less water.³ In the US alone, we use about 20 gallons of water per day per person on flushing. It's the single largest use of household water. Over the course of a year in this country alone we flush 2.2 trillion gallons of water down the drain. It's almost as bad as the national debt -- and that's with our government-mandated 1.5 gallon economizing toilets.

So, here's the rub: I have an awesome toilet design that I'm really excited about. But I'm a busy guy; I have a family and kids; I work all day selling goniometers; I don't have a lot of time to develop my plans for the Gates challenge. Nonetheless, I think my design would win. Here's the deal: I'm going to tell you how to design a better toilet. All you have to do is develop the plan, finish a few details, and submit it. When you receive that big check from the Gates Foundation, I just ask that you remember me and try to be a little generous.

Now here's the design: Start with a squat toilet. If you don't know what that is, go to http://en.wikipedia.org/wiki/Squat_toilet to learn more. I first ran into one of these while visiting Uruguay, but they can be found in many developing countries. The squat design is really quite clever and some of the advantages are detailed in the Wikipedia article. However, the most compelling advantage in my view is that your buttocks never come in contact with a toilet seat which can transmit disease, germs, and even STD's. It's a very sanitary way of taking care of business.

The squat toilet still requires water just like the flush toilet to wrap things up and we already decided we need to use less water. So I would change the material in the bowl to a rugged long-lasting superhydrophobic nanosurface which would eliminate the need for a flush since the waste would roll off the self-cleaning surface, through a spring-loaded flapper valve (made of the same superhydrophobic material) and into a depository.

Now this is where you come in. I've done the hard part and everything is now safely and sanitarily captured and ready for further processing. You'll need to figure out a way to get rid of it. Here are some suggestions: turn it into fertilizer, collect the gas to use it for heating or energy production, dry it out to make bricks, insulation or other building materials. If you're thinking of developing a car that can run on the methane gas which can be derived from it, think again; someone else beat us to it.⁴

Well, good luck. While you're developing the superhydrophobic material for the bowl and flapper valve, should you have a need to characterize the surface by measuring the contact angle, advancing and receding contact angles, roll-off angle, and surface energy, give me a call and I'll set you up with the right tool.

¹ See: http://tinyurl.com/3ryf7qa and http://tinyurl.com/3u6j76u
² See also: http://tinyurl.com/3jv5m7s
³ See: http://tinyurl.com/6422lw
⁴ See: http://tinyurl.com/2fpy8j4
 

Every once in awhile some one asks me how to measure the contact angle of a fiber or small diameter part. This can be done quite easily using DROPimage Advanced. There are a couple of tricks to make this work successfully. In the Contact Angle Tool Options menu, you need to turn on the Right line option. You also must change the baseline from Horizontal (the default) to Vertical. Attach your fiber or small diameter part to the needle on your microsyringe assembly so that it is vertical and perpendicular to the test liquid surface. Immerse the part into the test liquid and then pull it out slowly. Use the fine adjustment on the microsyringe assembly to control the z-axis movement. Use the Contact Angle tool to capture and record the contact angle. The video below shows all of the steps clearly:

If you cannot see the video above, simply point your browser to: http://youtu.be/N68jbv-b4K8
 

We're pleased to announce our participation in the Eighth International Symposium on Contact Angle, Wettability and Adhesion which will be held in Quebec June 13-15, 2012. For more details including information on submitting an abstract, please see http://www.ramehart.com/newsletters/cas8.jpg