UMD algal flow technology cleans and increases oxygen content of the water while producing sustainable energy
The Maryland Department of Transportation Maryland Port Administration (MDOT MPA) was recently awarded an American Association of Port Authorities (AAPA) Award of Excellence for Environmental Mitigation for a demonstration project with the University of Maryland (UMD) that removes excess nutrient pollution and increases oxygen content in the Baltimore Harbor. The algal flow-way technology (AFT) is a linear raceway constructed at the Helen Delich Bentley Port of Baltimore’s Dundalk Marine Terminal, located on the Patapsco River, which feeds into the Chesapeake Bay. The AFT pumps water from the Patapsco River onto the raceway, which flows over a surface designed to enhance algal growth. As the algae grows, it cleans and oxygenates the water prior to its return to the river, while producing algae that is used to power a small fuel cell.
“This innovative project highlights the importance of good partners like UMD and the U.S. Maritime Administration, who share the mutual goal of improving the health of the Chesapeake Bay,” said Bill Richardson, MDOT MPA general manager of safety, environment, and risk management. “We thank AAPA for this recognition and look forward to instituting other environmental initiatives at the Port of Baltimore.”
Stephanie Lansing, associate professor in the Department of Environmental Science & Technology (ENST) with the College of Agriculture & Natural Resources (AGNR) and Extension at UMD, is currently leading this project to explore ways to actively reduce pollution in the Chesapeake Bay while increasing the overall sustainability of the Port. Peter May, assistant research professor, and Patrick Kangas, associate professor, both also of ENST, built the algal turf scrubber (ATS) treatment system using algae as a filtration system, resulting in excess nutrients being removed from the water. Nutrient pollution causes the water to be low in oxygen, killing the wildlife and throwing off the natural ecosystem.
“This represents a great collaboration between several ENST faculty and the Port for a number of years,” says Kangas. “We got more than five years of good data on the performance of the ATS while I was involved, and then Stephanie Lansing came on board and did a great job of working on the anaerobic digestion of the algal biomass to produce energy. It is really a ‘ground breaking’ project in several ways. As a large-scale ATS that was operated for a long time, this really demonstrated the Best Management Practice (BMP) concept that helped get the ATS certified by the Environmental Protection Agency and the state of Maryland for nutrient removal. But Lansing's contribution was critical in showing what to do with the algae once it was harvested after the nutrients were removed from the water.”
Lansing is working to use the algae produced from the treatment process as a sustainable energy source. Algae grows quickly and can be harvested by the Port once a week and fed into a series of three digesters, housed in small greenhouse-like structures that break down the algae to produce methane-enriched biogas. The biogas can be used as a supplement to power a fuel cell that produces electricity.
“Our work at the Port of Baltimore is at the core of the food-energy-water nexus, where we designed and studied the first pilot-scale anaerobic digestion system to receive algae directly from an algal flow-way and reduce pollutants from the Chesapeake Bay by using algae to power a fuel cell,” says Lansing. “The system integrates increased water quality and energy production with the creation of a fertilizer. By taking traditional agricultural practices and water quality research and applying it to an urban setting in a unique way, we demonstrated it was possible to clean up the Chesapeake Bay, improve water and air quality, reduce pollutants, and create renewable energy using our innovative technology.”
May adds, “While there have been published examples of using algae as a carbon source for anaerobic digestion through conversion to methane and then electricity, there has likely been no effort like the UMD-Port of Baltimore ecotechnology work with the ATS. Running the system for years proved the efficiency of ATS for its primary purpose, to remove nutrients from the Patapsco River as a mitigation pilot for the Port's 1200 acres of impervious surface runoff. A U.S. Department of Transportation grant attached the ATS to the UMD Waste to Energy Lab's anaerobic digesters, which received the wet algae harvested weekly. The methane produced was captured and bled into a microbial fuel cell on site that produced electricity and ran attached lighting. This effort took several experimental ecotechnologies and linked them up into a unique continuous system outdoors in a real world application. Clean energy power production was a byproduct of the primary goal of cleaning ambient waters for the Port's regulatory requirements. Using the harvested algae as a beneficial waste product in the treatment train to create clean energy was just innovative, ecologically-engineered icing on the cake.”
In addition to a recent publication in Ecological Engineering describing the utility of the algal turf scrubber for a source of anaerobic digestion and energy production, this work garnered external attention from numerous media outlets, including video stories from the BigTen Network and Voice of America.
“It was very exciting to work on this system for the first project of my PhD research, since it demonstrated how effective this type of combined algal water treatment and energy production is,” says Danielle Delp, third year doctoral student under Lansing in ENST. “The ATS is a system that requires very little - flat land, electricity, and sun - to provide continuous bioremediation to a polluted waterway. It's simple design and scalability makes it practical both as a means of addressing the persistent nutrient pollution in the tributaries of the Chesapeake Bay, as well as a reliable algal cultivation system for bioenergy production. This project will provide a foundation for future research to apply combined ATS-anaerobic digestion elsewhere in the watershed, particularly upstream in agricultural regions where ATS research has been limited so far.”