College of Agriculture & Natural Resources
Environmental Science & Technology

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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