Bright Green Future: Algal Turf Scrubber

Dr. Patrick Kangas examines algae from an experimental raceway utilizing agricultural drainage water on Maryland's Eastern Shore.

May 30, 2013

Initially developed to control water quality in aquatic microcosms in the early 1980s by Dr. Walter Adey at the Smithsonian Institution, Algal Turf Scrubber™ technology has been studied and refined for more than 30 years. With widespread projects across the continent, researchers lacked a centralized place where they could share information and collaborate. The Algal Ecotechnology Center was founded in 2011 by Dr. Patrick Kangas and Dr. Frank Coale, faculty in the Department of Environmental Science and Technology, to serve that purpose. The new center aims to advance the design and implementation of ecologically-engineered algal technologies for water quality management and economic development.

The Algal Ecotechonology Center evolved from collaborations that had developed over several years during grant research, including funding from USDA, the Lewis Foundation, and the Norwegian oil company, Statoil. Through the succession of these grants the number of researchers working on the Algal Turf Scrubber technologies has grown in number. “The idea behind the center was to create an institution that could transcend any individual research project to foster collaboration on algal-based technologies and green economy development,” explains Dr. Kangas, who has been studying algae since 1979. The center has no external funding, but its website, supported by the Environmental Science and Technology Department at the University of Maryland, serves as an electronic clearinghouse for information about algal-based technologies. “The current geographic focus for the center is on the Chesapeake Bay Watershed,” says Dr. Kangas, but the long-term vision is to move to the Mississippi River watershed and even China.


Algal turf scrubber exploits algae’s natural ability to utilize excess nutrients, offering unparalleled performance in the removal of nutrients and pollutants from wastewater and polluted waterways. “Algal production for water quality improvement demonstrates that the technology removes nutrients and sediments while adding dissolved oxygen to the water,” explains Dr. Kangas. “Furthermore, the algal biomass produced by this process, can be used as a feedstock for biofuel, fertilizer and other potentially valuable byproducts.”

The algal turf scrubber consists of a community of natural algae, attached to screens that are placed in the shallow treatment channels or raceways. The process involves pumping water over the screens, allowing the algae to perform its function. “Periodic harvest of algae removes pollutants from the water that have been incorporated in the algal biomass,” says Dr. Kangas.

The efficiency of the algal turf scrubber as a waste treatment technology is directly related to the rate of algal growth - the faster the algae grow, the greater the pollutant uptake rate. “The rate of algal growth is controlled by manipulating water depth, flow rates, and concentrations of nutrients in the water that is being treated. All these factors can be adjusted to maximize algal metabolism and, thus maximize water treatment capacity,” tells Dr. Kangas.

In fact, biomass production rates of algal turf scrubbers are among the highest of any recorded values for natural or managed ecosystems. For this reason alone, researchers see a tremendous potential for cleaning up and restoring the Chesapeake Bay. Dr. Adey, the original inventor of the technology, estimates that approximately 3,000 acres worth of scrubber systems installed near the headwaters of the Chesapeake Bay could help regulators meet restoration goals and even turn over the Bay’s entire dead zone in only one year.

CASE: Great Lakes
Large Scale Turf Scrubber

ENST alumnus and currently assistant professor at the State University of New York at Buffalo- Dr. David Blersch, has instituted a research program to assess the sustainability of algal cultivation technologies for pollution control and biomass production in Great Lakes communities.

The nearshore environment of the lower Great Lakes has been impacted by a shunted nutrient cycle, caused partly by invasive Dreissenid mussels, which drives excessive production of harmful benthic algae. “I’m researching applications of controlled benthic filamentous algae cultivation for mitigating nutrient loadings and controlling wild algal production in the nearshore Great Lakes,” explains Dr. Blersch. Currently, he is investigating the use of ATS in both agricultural and urban settings, where ATS are being installed on abandoned industrial field sites in Buffalo to decrease effects of urban stormwater runoff.

Dr. Blersch is also examining the economical aspects of ATS, focusing on the algal biomass produced in a variety of cultivation methods and its potential as a bioenergy feedstock. In addition, he is looking at the development of feedback control for the optimization of the algal production processes. “The development of this technology is critical for the economical implementation of large-scale algae farming,” says Dr. Blersch. Feedback control designs for ecologically-engineered systems is a novel and promising field that will reveal the real potential and performances that can be expected out of ATS.

CASE: Baltimore Inner Harbor
Experimental Scrubber & Education

ENST alumnus and current environmental scientist at Biohabitats, Inc.–Dr. Peter May, has implemented a pilot research program to assess the suitability of algal cultivation technologies for Baltimore Harbor nutrient reduction and oxygenation. Dr. May is also working with Baltimore City middle school in developing lesson plans around the use of algal ecotechnologies.

With high nutrient loads coming into the harbor of Baltimore’s urbanized watershed, periodic algal blooms have in the past caused large fish kills resulting from oxygen depletion. Dr. May has installed an experimental ATS raceway on the Inner Harbor to test its potential role as a living filter of polluted urban runoff, using sunlight and photosynthesis to create biomass and to pump high concentrations of dissolved oxygen into the harbor. Because the ATS project has been assembled on the property adjacent to their East Harbor Campus, Living Classrooms teachers and staff member will be involved with the project as part of an environmental education program. Biohabitats scientists will work with Living Classrooms’ staff to develop an active learning curriculum centered on the ATS project which will run throughout 2012. Students will learn elements of biology, chemistry, ecology, economy, and sociology as it relates to water pollution and its treatment with algae. “Education is key here with the unique connection between Living Classrooms and the University of Maryland. There are so many interesting opportunities for learning with the ATS system across multiple levels, so it’s very exciting to be working with grade school students and teachers as well as local university researchers toward a common goal,” says Dr. May.