Teliot

Inspiration and background

Our team was looking for ways to identify unnecessary usage of water. Then we thought of the toilets in our homes that had an added feature of the dual-flush and started to wonder why we don’t see this feature in public restrooms. It turns out that according to most common public toilets, one flush releases an average of 1.6 gallons of water. However, the amount of water released for liquid waste is 1.1 gallons in dual-flush toilets in residential homes. This would mean that if a user urinates in a public bathroom, there could be about 0.5 gallons of water saved per flush if the toilet could classify solid and liquid waste. However, because the process is not readily available in many places and is not automatic, the water savings are not maximized, which is the issue we decided to analyze and develop a solution for. Looking at the Atlanta Jackson-Hartsfield International Airport as a case study, we calculate that the upfront cost of installing our design of dual-flush toilets will break even with the water savings in approximately 22 months. With the feasibility of this project checked, we decided to move on to the details and the implementation of our design on a conceptual level.

Conceptual Design

How flushometers work The link prior shows how flushometers work with an explained diagram and annotated part names. We determined that the size of the bypass hole is directly responsible for the amount of time it takes for the upper and the lower chamber to equalize in pressure. This would mean that a larger bypass hole size would lead to a shorter time for the pressures to equalize, leading to a decreased amount of water flow for the reduced flush. The opposite would be true for a full flush with a smaller bypass hole size. In order to do this, we had to first create a detection system that could distinguish feces from urine. We decided that the most cost effect and accurate method for this was using a ultrasonic sensor that would be built into the inner surface of the toilet bowl. This sensor would be set to a certain range so that solid matter would be detected and the state of the sensor would recognize the feces. This would then communicate with a central microcontroller that controls a servo motor, which is connected to a long cylindrical rod embedded inside the flushometer. This rod would control the bypass hole size as either normal or covered depending on whether the sensor's input signal. The next steps would include fine-tuning this process so that the desired flow volume of 1.1 gallons and 1.6 gallons would be released for the two cases.

Challenges we ran into

To determine what type sensor we wanted to use, we first had to ask ourselves the question of what characteristic distinguish feces from urine. This was difficult because many factors differentiated these two components, but only volume and proximity to the bottom of the bowl were useful for sensing.
Sensor choice for distinguishing solid from liquid waste was difficult because we were originally considering using capacitance sensors because of its ability to detect solids through a wall. We were planning to use the sensor and attach it on the outer surface of the bowl, but we found out the range of the sensors were maximum of 3 inches, which was not enough. This led us to a different design using an ultrasonic sensor that would be embedded on the inside of the bowl.
While creating a mechanical device that would switch from reduced flow to normal flow, we had to come up with a mechanism that would have two degrees of freedom controlled by a servo motor (vertical for diaphragm and horizontal for linear actuation). To get around this issue, we came up with a different mechanism that uses a rod from the top that is controlled by a linear actuator so that there is only one degree of freedom.

Accomplishments that we're proud of

We are proud that we were able to not only learn how a general flushometer works in the span of less than 24 hours, but also identify a method in which we could insert our knowledge to create a more efficient system that saves more water. We believe that we navigated the obstacles and challenges presented to us and used the time and resources allotted to us in the best manner.

What we learned

We learned that developing a system that can be applied in real-world situations is very difficult, and that there are many variables not related to technology that we must consider. Despite all the obstacles and roadblocks we encountered while flushing out our ideas more in depth, we also learned how to prioritize our goals and communicate with one another to efficiently delegate tasks.

What's next for Teliot

Teliot is very excited for our future works. Regardless of the results of this competition, we plan to:

Experimentally test and validate the rod mechanism for bypass hole size classification. We also wish to explore continuous bypass hole size changes rather than the discrete system we developed.
Transfer the wired connections from the sensor to the microcontroller to a wireless system.
Prototype and build the bowl system to include the ultrasonic sensor with casing.
Begin to talk with public institutions such as airports and schools for employing this technology across the state.

Thank you for the opportunity to brainstorm and develop solutions to real-world issues. This weekend has really been a pleasure and we would like to thank everyone for making this event possible.