Successful aquaculture and mariculture operations require high quality water conditions which include maintaining ideal dissolved oxygen (DO) levels often near or above atmospheric saturation levels. Transferring oxygen into the water usually involves passing gas bubbles through the water, passing water droplets through the air or pre-dissolving oxygen into a slip stream of water. Within these broad categories, a variety of technologies exist to transfer oxygen into water and selecting the best technology depends on a variety of factors. The farmed species and the hatchery configuration play critical roles in determining the best available technology, however other factors include water quality goals, total gas pressure, water depth, surface area, salinity, temperature, power availability, etc. Additionally, cost and availability of liquid oxygen, rate of oxygen transfer required, installation requirements, maintenance, as well as process redundancy requirements should also be considered.
Within those broad classes of aeration/oxygenation technologies, some common choices include diffused air (coarse or fine bubble), nanobubble technologies, venturi aspirators, saturation vessels such as speece cones and other saturation technologies, brush/paddle aerators, cascade systems, and low head oxygenation systems. Each technology has benefits and limitations and understanding these differences may lead to an optimum selection for a hatchery or farm. A key part of ensuring adequate DO levels is accurately measuring and reacting to changes in the levels.
This presentation will review each of the identified technologies to include design and installation considerations, operating parameters, control/measurement implications and provides a framework to evaluate the different options on a life cycle cost basis.