Video showing the toilet system, how it processes the waste, converts the solids into energy and stores this energy to electrochemically treat the liquid waste
RTI’s design will accomplish three primary functions: disinfect liquid waste, dry and burn solid waste, and convert the resulting combustion energy into stored electricity. The system also includes innovations to improve operational utility, energy efficiency and cost.
The solid waste drying process will use a combination of mechanical, solar and thermal energy. A mechanical screw-like device will separate out liquids and begin the process of converting solid waste into combustion fuel. Solar energy, natural drafts and heat from burning waste will further aid the drying process. As it dries, the waste will be broken down into uniform-sized pellets, which will be burned using a novel combustion unit designed by our partners at Colorado State University. This self-powered unit also captures a portion of the heat produced and converts it into electricity.
Liquid waste—including urine and liquid that is removed from the solid waste—will be disinfected through electrochemical processes using carbon electrodes (developed in partnership with Advanced Diamond Technologies, Inc. and Duke University). The disinfected water will be suitable for use as rinse water for the toilet or as a fertilizer supplement.
September 27, 2014
It’s been a bit since we gave an update on the status of our Liquid Waste Processing Unit so we thought we would take some time and put up a quick post about the unit and the recent changes we are evaluating with it.
Electrochemical Treatment of Urine and Feces
First and foremost we’ve started evaluating the use and efficacy of a different type of electrochemical cell in the liquid disinfection system itself. This electrochemical cell is adapted from a commercially available consumer product, which is good for several reasons, chief amongst them: potential lower cost and energy requirements.
During this evaluation, we’ve found the initial test results to be very encouraging! (see below)
The photo on the left shows a tank of urine and feces prior to electrochemical treatment. The photo on the right shows the same after treatment.
Urine and Feces disinfection test results
Plot of E. coli concentration and energy consumption over the course of a treatment test.
The 90 L tank test
We are also in the process of testing a larger 90 L processing tank.
During field trials of the RTI toilet, liquid waste processing will be carried out once a day. This process needs approximately 90 L of waste to complete.
Due to the larger size of this processing tank, tests are currently being carried out to understand how this level of scaled up processing would impact the overall function our toilet.
Those results will be posted here as soon as they are available!
March 31, 2014
On March 21, 2014, during the Reinvent the Toilet Fair, Brian Stoner had the pleasure of being interviewed by Elisabeth von Muench from (Sustainable Sanitation Alliance (SuSanA)) at Taj Palace Hotel in Delhi, India. The two-part interview was filmed by Arno Rosemarin (SEI).
In the first part, Brian introduces our system and in the second part, he walks them through each part of the waste management process, describing the features therein.
January 24, 2014
The integrated toilet system with solid waste processing and liquid disinfection modules integrated underneath
RTI prepares its first generation Reinvent the Toilet processing system for the 2014 Toilet Fair in Delhi, India. The system includes a custom-designed squat plate by Roca Sanitario and a self-contained waste treatment system. The open-lid on the right, shows the solid waste combustion unit that exhausts to a stove-pipe running up the right side of the system.
December 13, 2013
Roca toilet engineering team with Brian Stoner (RTI) demonstrate novel squat plate
Roca engineers have developed an ultra low-flush squat plate to go with RTI’s toilet processing modules. This novel squat plate is designed to operate with 1.5 liters of water, maintaining an effective water seal and minimizing odors. This latest advancement in toilet technology is an essential part of the strategy to bring effective sanitation to regions that lack sewage infrastructure. The squat plate dispenses into a solid-liquid separator that converts solid waste into burnable fuel and electrochemically disinfects the liquid for flush recycling and non-potable uses. The video below shows a 1.5 liter laboratory test-flush using simulated specimens.
December 6, 2013
RTI recently received two additional awards from the Bill & Melinda Gates Foundation to support our team’s efforts to reinvent the toilet for the developing world. These awards will enable us to more quickly conduct testing of our system with actual human waste (as opposed to simulant materials) and to build a full prototype unit in partnership with Roca, the largest toilet manufacturer in Europe, who will develop a custom squat plate for the unit.
Below, RTI team members pose after constructing their first integrated toilet system with custom squat plate (designed and manufactured by Roca). The system incorporates an auger-based solid-liquid separation stage followed by solid combustion (pictured in the lower right) and liquid disinfection processing modules.
See a press release on the new awards here.