Overview
The Algal Ecotechnology Center (AEC) is an organizational unit for advancing the design and implementation of ecologically-engineered, algal-based technologies for water quality management and economic development. These kinds of ecotechnologies utilize natural or “wild” assemblages of algal populations for uptake of pollutants, such as excessive nutrient concentrations, into their biomass during growth. These pollutants are removed from the water by periodic harvesting of the algae. Dissolved oxygen also is produced through photosynthesis by the algae, which adds to their role in water quality management.
The algal biomass that is harvested from these systems can be used in productive ways, such as a feedstock for biofuel generation or as a fertilizer, thus supporting local economic development. The systems are ecologically-engineered by using lowquality, solar energy as their main driving force, with smaller amounts of high-quality, purchased energies and materials used only to amplify the algal growth.
The center consists of a set of collaborators, from academia, industry, and governmental and nongovernmental organizations, who have agreed to work together to advance the algal-based ecotechnologies. Collaborations are facilitated by a website administered in the Environmental Science and Technology Department at the University of Maryland at College Park. The web site is a clearinghouse for publications, project descriptions, and informational materials about the ecotechnologies.
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What is an Algal Turf Scrubber?
What is an Ecotechnology?
A technology is a method for solving a problem. It consists of a set of plans for achieving a specific goal that has been developed over time through experimentation. Thus, in the simplest sense, a technology is a form of information but the term also refers to actual systems that have been built to provide useful work for society.
An ecotechnology is a class of technology that includes a living ecosystem as part of the method for solving a problem. In this context the ecosystem consists of an interacting set of “wild” or natural species that are allowed to self organize within specified boundary conditions in order to function as a part of the solution to a problem. An ecotechnology is therefore a hybrid system with a non-living part that is designed by humans and a living part (the ecosystem) that self-designs. These kinds of systems are described as being the product of ecological engineering. Examples are treatment wetlands, rain gardens, vegetation used for erosion control and algal production systems (such as the Algal Turf Scrubber™) used for water quality management.
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What is an Algal Turf Scrubber?
The Algal Turf Scrubber™ (ATS) is an ecologically engineered technology (e.g., an ecotechnology) used to remove nutrients from a water body and to produce biomass which in turn can be used for several purposes (biofuel feedstock, fertilizer, health products). This technology was developed as a low-cost, more environmentally-compatible alternative to conventional technologies for water quality management by Dr.Walter Adey of the National Museum of Natural History of the Smithsonian Institution. The ATS was developed based on natural algal communities that grow on the crests of coral reefs. Because of the convergence of energy sources on a coral reef (high temperatures, high diurnal sunlight and the pulsing surge of waves), coral reef algal turfs have among the highest productivities of the Biosphere. The ATS simulates the conditions of the reef crest with surges of water from pumping that flow across shallow beds of attached algae.
The ATS system consists of an attached algal community growing on screens in a shallow trough or raceway through which water is pumped. The algal community provides water treatment by uptake of inorganic compounds in photosynthesis. Water is pumped from a waterway onto the raceway and algae remove the nutrients through biological uptake for growth as the water flows down the raceway. At the end of the raceway water is released back into the waterway, with a lower nutrient concentration than when it was pumped up onto the top of the raceway. The nutrients that have been removed from the waterway are stored in the biomass of the algae growing on the screen. The algae are harvested, approximately once per week, during the growing season thus removing nutrients from the waterway in their biomass. Because of the fast growth rate of algae on the ATS, this technology can remove nutrients at a high rate. Harvesting is important since this action rejuvenates the community and leads to high growth rates. In fact, biomass production rates of ATS are among the highest of any recorded values for natural or managed ecosystems.
The on-land ATS was invented and patented in the 1980s by Dr. Adey. Commercialization of this technology is underway through a company named Hydromentia that is headquartered in Ocala, Florida. A related, in-water algal production system has been developed recently that utilizes an attached algal community growing on screens that are suspended in a waterway from a floating platform. This new technology extends the application of controlled algal growth and it is a focus of research and development. Both the on-land and the in-water algal production systems offer multiple innovative features for water quality improvement and biomass production.
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Innovative Features of the Algal Production Systems
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They are driven primarily by solar energy through ecological engineering design.
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The primary mechanism of pollution uptake is photosynthesis by a multispecies community of native algae.
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Because algal production systems rely on photosynthesis, they not only remove pollutants but they add oxygen to the water.
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They are a very flexible, modular technology that can be designed into available land and water areas where water quality is impaired.
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Pollutant removal performance is very transparent and easily assessed through analysis of rates of biomass production and the chemical composition of the biomass.
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They produce a valuable byproduct in terms of algal biomass that can be the basis of green economies.
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