Project Lead(s): Amy Bilton
Aquaculture is a major food source in many low- and middle-income countries (LMICs).
Improving water quality for aquaculture can increase yields, improve food security and reduce antibiotic use.
Aeration can significantly improve water quality, but high cost limits its use in LMICs and current aeration methods require a secure electrical connection, which is not always available.
The objective of this project was to improve fish farm production by developing a new aeration method for aquaculture ponds that does not require electricity, has low maintenance requirements and which can be inexpensively fabricated and deployed in low-income countries.
The technology distributes dissolved oxygen (DO) generated by photosynthesis using convection.
The system uses a solar thermal absorber plate and a thermally conductive rod to transfer heat to the bottom of the pond to heat the bottom water. By warming a portion of the water at the pond bottom, the water will rise, mixing the oxygen-rich water from the top through the entire pond depth, increasing the available DO reservoir.
The convective currents are induced using low-cost passive solar thermal collection plates (above the water surface) and insulated heat transfer channels to heat water at the bottom.
To evaluate the design, DO levels were monitored in the pond, close to the device at the top and bottom, and control measurements were taken at a distance of 20m from the device in the same pond. This was tested in Vietnam.
Statistical comparison between the two measurements showed the DO at the pond bottom was increased by 19% during the day and 6% at night.
Based on the results of the tests in Vietnam, the team was able to secure an additional $500,000 USD for a randomized controlled trial of the approach in Bangladesh. They intend to scale-up the technology once the trial is complete.