COMPOST TEA PROJECT
Dartmouth Humanitarian Engineering
Design Lead
Quito, Ecuador
SKILLS
Cost Analysis
Design for Manufacture
Design for Assembly
Rapid Prototyping
CHALLENGE
Design and implement a hydroponics system for farmers in Ecuador to help improve soil health and increase crop yields.
OVERVIEW
The Dartmouth Humanitarian Engineering club mission in 2017 was to create a hydroponics system capable of creating compost tea out of materials accessible to Ecuadorian farmers. Compost tea is made by first circulating water with a pump to create aeration in the water. After the water has been aerated, bacteria in the system can feed off the additional oxygen and generate essential plant nutrients such as Nitrogen, Potassium, and Phosphate. This project was done in conjunction with CONQUITO, an Ecuadorian NGO, and Universidad San Francisco de Quito, a top Ecuadorian University. The project also included a 3-week research and implementation trip to Quito, Ecuador to research Ecuadorian agricultural practices and implement our prototype at farms in Ecuador. As the design lead, I created and modified our compost tea design to yield the most nutrient-dense tea using minimal energy.
MY CONTRIBUTIONS
First Prototype
We began this project by creating a very crude prototype to prove this was a viable concept. The first prototype consisted of two stacked buckets, a pump in the bottom bucket, and attaching PVC pipes to create a vortex of water. Prototype test revealed that the water was heated to over 110 degrees Fahrenheit. This was problematic because in order for the compost tea process to be effective, the water has to remain around room temperature. Although our first prototype did not work as expected, we learned from these missteps and made a better, more-efficient, second prototype.
Second Prototype
For the second prototype, the design was modified, simplified, and optimized from our first prototype. First, we added a weaker pump that would be just as effective as the stronger pump but less likely to overheat. Also, we changed the design of the PVC pipes to inject water from the bottom of the top bucket instead of the top of the bucket. These changes both yielded great results for us and the water temperature significantly dropped. Most importantly, we saw an increase in the NPK levels in the compost tea which is a key indicator for compost tea quality. The prototype was effective; however, the challenge of scaling the prototype for larger garden persisted.
IMPLEMENTATION TRIP
Final Prototype
The next progression for the third prototype was to scale the design from five gallons to twenty-five gallons, about the size of a trash can. The primary challenge for this prototype was creating similar quality compost tea as the smaller scale design using the same pump. This was achieved by simplifying the design to a "T" shape to achieve a comparable flow rate as previous designs. This design was very effective. It is also very cheap to operate at about 5 cents per gallon. In the long term, the project goals are to reduce the cost of the systems which is around $90, and to begin studying how to most efficiently apply this compost tea to plants. We came to this design after talking with local Ecuadorian farmers about their specific needs and resources available at their respective farmers.
Visitation & Implementation
The trip to Ecuador was a great experience. We set out to achieve some ambitious goals and exceeded these expectations. Our first goal of profiling and understanding orchards through interviews and soil testing was completed within the first week. With this information, we began to focus on the South of Quito because their problems of poor soil align better with our prototype. We also sought to understand current composting methods in Quito. We quickly discovered that farmers rarely use traditional compost. The compost methods that were used, such as Biol and Poulin, were slow to produce and ineffective. Our most challenging goal was to build a prototype in Ecuador, and we successfully built two separate prototypes with locally sourced materials. We were very happy with the compost tea these prototypes produced.
Collaboration
This project also included collaboration with many separate entities, and reinforced my belief in thoughtful design and effective communication. We worked with students and professors from Universidad San Francisco de Quito. We also worked with farmers, food distributors, and representatives from the NGO. Working with all of these groups meant we were able to pitch our design, answer any subsequent questions, and thoroughly understand our system. Without a deeper understanding of the processes in our system, we would not have been able to effectively answer these important questions. Explaining our ideas to not only non-technical people, but also primarily Spanish speaking farmers was a challenging experience, but I learned how to be an more effective communicator.
IMPACT & CONCLUSION
Our compost tea has yielded great results with farmers in preliminary testing. Further, this trip and project have afforded me a deeper understanding of the design process and the inevitable challenges that will occur throughout the process. We had no reason to suspect the first prototype would overheat. But once it did, effective changes were made from the first to second prototype. Although our second prototype made high quality compost tea, we had to find a way to scale it to serve larger gardens. Lastly, building an entirely new prototype in a foreign country had many challenges in itself, but through this all we created an effective prototype.
Article from NGO: http://www.conquito.org.ec/estudiantes-de-universidad-de-dartmouth-desarrollaron-prototipo-para-huertos-urbanos-de-quito/
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