Gas Transfer Membranes: Recreating Deep Sea Water at Sea Level

Kyle Harrigan

Water Systems Engineer

Monterey Bay Aquarium

Monterey Bay Aquarium’s newest exhibit, Into the Deep, showcases amazing animals from the deep sea, many of which have never been observable by the public before.  Much of the challenge in designing a successful deep sea exhibit stems from two hurdles that must be overcome: the difficulty of finding and collecting these animals, and the difficulty of replicating an environment for these sensitive animals to thrive in.  To overcome these challenges, the exhibit leverages MBARI’s expertise in deep sea exploration and new, custom-built holding systems designed in-house at the aquarium.
The workhorses for the exhibit are gas transfer membranes, which provide a highly tunable toolkit for managing total and individual dissolved gas concentrations within seawater.  A semipermeable membrane allows molecules to exchange between liquid and gas streams while keeping the two phases physically separated from each other; by modifying conditions in one phase, conditions in the other phase will adjust to move closer towards thermodynamic equilibrium.
This talk will focus on what gas transfer membranes are, how they work, and how we’ve used them in this nontraditional application to recreate the deep sea at sea level.  After developing a basic understanding of their operating principles, the talk will discuss the robust life support system built around these gas transfer membranes that tailors the water to the specific needs of an animal: temperature, pH, and dissolved oxygen.