In partnership with Blue Water Baltimore, and through a grant from the Abell Foundation, KCI conducted a pilot study to evaluate the direct treatment of a portion of the harbor to increase dissolved oxygen. Throughout the world, estuaries like the Chesapeake Bay experience anoxic and hypoxic conditions, or dead zones, leading to algal blooms and fish kills. Low oxygen levels, most often a result of increased nutrient loading, prohibit growth of underwater grasses and increase mortality rates among many aquatic species.
The study applied techniques frequently used in closed systems, like wastewater treatment plants and inland lakes, to the distressed tidal waters of the Patapsco River, a major tributary to the Bay. The goal was to demonstrate that the engineering principles of aeration and mixing can be applied in an open water estuarine ecosystem with predictable and measurable results that could be used for future systems.
Environmental and marine engineers worked together to design and build an aeration system comprised of a SolarBee®, a floating device that draws cooler water up to absorb oxygen at the surface, and a diffuser array that pipes oxygen directly into the water below. Once launched, engineers and scientists took weekly readings to track and monitor dissolved oxygen, water temperature, salinity, density and conductivity. Green tracer dye was used to track the device’s range of influence within the water.
The goal of the project was not to make a long-term impact, but to place a unit that we configured with known power settings and then measure its influence.
Christopher L. Overcash, PE, BCEE, LEED AP, ENV SPVice President, Practice Leader
The results of the scientific study have provided valuable information on how mixing and aeration affect dissolved oxygen concentrations within a dynamic open water marine system, and may lead to additional funding for a larger pilot study.