The University of Toronto will oversee a small team conducting research focused on design, and analysis of the new aquaculture aeration technology. The University of Toronto has partnered with Curiositate to provide industry feedback and consultation throughout the development of the technology. A partnership has also been formed with BRAC for field trials and planning for technology scale-up.
Aquaculture is a large industry in many low income countries (LICs); fish farms account for about 5 percent of the GDP of Bangladesh. Improving the quality of aquaculture pond water has the potential to increase fish yields, raise incomes, and improve food security. In large aquaculture facilities, aeration has been shown to improve water quality and increase yields. However, aeration equipment is costly and requires electrical power inputs which can limit its use in LICs. Dissolved oxygen (DO) that is used by the fish is provided by photosynthesis, which is related to sunlight and takes place during daylight hours. The oxygen is produced at the pond surface and much oxygen is lost to the atmosphere. By circulating the water, more oxygen can be introduced.
The University of Toronto’s proposed approach is a new aeration method that does not require electricity, has no moving parts, has low maintenance requirements, and is inexpensive to fabricate and deploy in low income countries. The system uses heat that is captured through a solar thermal absorber and transferred to the bottom of the pond to heat the water. The heated water will rise and mix the pond, spreading oxygen-rich water from the top through the entire depth of the pond. This increases the DO reservoir and can result in improved water quality and higher pond yields.
The passive aeration system will increase pond dissolved oxygen levels to improve water quality, allow for increased density of fish stock, higher fish yields, as well as larger fish that have a higher market value and demand. At higher levels of dissolved oxygen, fish feed is also used more efficiently, which reduces operation costs. The solution is an alternative to power-hungry aeration systems that consume significant amounts of energy and capital. For farmers not using aeration, the technology will provide all of the benefits described above. For farmers using aeration, replacing or supplementing existing devices can greatly decrease energy consumption for aquaculture.
Using the Powering Agriculture funding, refinement of the device design has continued in order to use the solar thermal energy more efficiently in the aeration process. In addition, the effects on farmer yields are being evaluated. In 2018, two new versions (versions 3 and 4) of the aeration device were developed. Following the redesign, The University of Toronto refined the original 34 devices deployed. These units were replaced with 34 upgraded devices, which have been placed with14 farmers. Each installation includes a control pond in addition to the pond with the aerators installed to allow evaluation of the impacts of the device on farmer yields. The University of Toronto has installed 57.54kW of solar capacity to date. The project is now gathering data from the newly installed devices; the test results will be compared with the performance of previous versions. The University of Toronto’s award has been extended to November 2019.