When we first joined the hackathon, we began by researching the various large-scale changes that happen during a drought crisis and how they affect the humans and ecosystems that are susceptible to changes in water abundance. We began with California but wanted to keep an open mind about how this may apply to other parts of the world where drought is an issue. We quickly found that drought caused far more changes than just a simple shortage of water: it was responsible for an increased salinity in groundwater and quicker soil runoff rates, meaning the water that is applied to the soil doesn't stay put. This poses a major issue for farmers who have to resort to overwatering, which becomes increasingly expensive, and less efficient with a decreasing water supply. Additionally, farmers see a decrease in crop yield when their plants are in a saltier soil.

What it does

We decided to give farmers another option: remove the salt before they irrigate. With this option, farmers can use electricity to separate the salt from their water, allowing them to use only the water that they need to grow their crops at the maximum yield they can achieve.

In short, we built a desalinator for individuals, and it's called EDDI.

  • EDDI is an appliance. Its size makes it perfect for smaller farms, and it connects into existing utilities.
  • EDDI is scalable. Simply add more layers and voltage, or chain two devices together and you can increase your desalting capacity.
  • EDDI is intelligent. You can control it and monitor it from any internet-connected device in the world. With the EDDI web application, you can easily visualize your water's salinity, and how much salt is being removed. You can even download a spreadsheet to analyze your groundwater and plan for your next year.

How we built it

We used a technology called Electrodialysis, where an electric field is used to separate salt ions from neutral water. This technology uses a series of water channels separated by ion exchange membranes which allow only a certain kind of ion to pass through them. We designed and built our own stack of these channels and membranes as well as all of the plumbing and circuitry that goes into controlling the flow of water. We also built circuits for introducing the electric field into the desalination stack, and switching the polarity of the stack in order to prolong the device's lifetime. We also integrated salinity and flow sensors to detect the state of the device.

The Artik acted as the brains and communicator for our device. We utilized almost every GPIO pin of the Artik (it has a lot!). We used a C program with unix sockets to monitor the sensor readings, and we used Node.js to control the circuitry. We used Firebase to store and read our sensor readings and user settings in real time.

We designed and built a custom web application for the EDDI. The application is entirely a frontend app made with React.js. The app is designed for ergonomic use and ease of understanding. We've provided an easy way for farmers to visualize and understand water salinity, which is not an immediately intuitive idea to grasp.

Challenges we ran into

As with all hardware projects, what we built took a much longer time than we anticipated. We ran into several roadblocks along the way in all parts of the process.

During circuit building, we were just learning how to use transistors, so we tried many circuit designs and blew many transistors before we were able to use them correctly.

During the mechanical design, our biggest difficulty was preventing the device from leaking. There were many points where we had to drastically change our design in order to prevent leakage. We also had difficulty in figuring out how to cut the materials, but eventually found a few methods that worked really well.

Accomplishments that we're proud of

We didn't electrocute ourselves!

But seriously, we are all so proud that we were able to pull all of our individual contributions together and make a device that works the way we set out to make it work in a very limited amount of time. We learned so many new things together, and didn't forget to have some fun with it.

What we learned

  • The Artik environment
  • Soldering and patience.
  • How to use transistors the wrong way.
  • How to use transistors the right way.
  • How to use a Laser Cutter!
  • The importance of gaskets in machines that work with pressure.
  • How IoT can change the way we understand the tools that we use.

What's next for EDDI - ElectroDialysis Desalinator for Irrigation

We intend to make several improvements going forward. This is our working list, but it continues to grow every week:

  • Adjusting the details of the device to make it leak less, and make it more durable.
  • Slimming the device as much as possible
  • Adding the ability to run the device on solar power and monitor the battery level and power usage.
  • More rigorous testing with real plants.
  • Investigate increasing power efficiency and reducing cost.
  • Look into using BLE or Bluetooth to access the data without an internet connection.
  • Adding the option to automate the desalinator with more practical user inputs like type of crop, size of field, or ideal volume of water.

Special Thanks

  • Columbia CMS (Laser Cutter and workspace)
  • Professor Ngai Yin Yip (Mentorship)
  • Hang Xu (Membrane Broker)
  • Hampton Chutney (Keeping our bodies and minds fueled)
  • Rayogram (Meeting Space)
  • Alice Wong (Immense Patience)

Built With

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