CONTINUED BIOMASS OPTIMIZATION OF ALGAL TURF SCRUBBERS FOR AQUACULTURE AND BIOFUEL APPLICATIONS

Algal turf scrubbers (ATS) have been widely used since their invention for efficient nitrogen and phosphorous removal from natural and man-made waterways.  The system is typically arranged as a downward sloping flow-way onto which a mesh matrix is attached to assist in colonization by epiphytic algae.  As water flows over the developed algae mat, soluble nitrogen and phosphorus are assimilated by the algae.  These systems have recently gained interest by the biofuels community due to their ability to produce large amounts of biomass at costs which are typically less than microalgae production.  Our research over the past 3 years has focused on the optimization of these systems for maximal biomass production and nutrient removal.   

Our current research has focused on testing different matrix types (i.e. polypropylene, polyethylene, etc.) as well as different matrix attachment structures (i.e. 1-dimensional, 2-dimensional, 3-dimensional).  Current research has utilized a 12 lane, 40 foot long ATS system located on a pier at Priest Landing in Savannah, Georgia.  Trials are conducted on a year long basis to assess seasonal productivity and nutrient removal.  Water samples are taken daily to monitor nutrient (ammonia, nitrite, nitrate and phosphorus) removal.  Solar intensity, wind speed, wind direction, air temperature, relative humidity, and precipitation are also measured daily.  Twice a day (a.m. and p.m.), dissolved oxygen, salinity, temperature, and pH are measured with a portable meter and recorded for each ATS lane.  Biomass is harvested once a week and analyzed for biochemical composition (protein, lipid, ash, and energy) to determine its potential as an aquaculture feed ingredient and/or bioenergy source.  Samples are also collected weekly to determine the amount of algal grazers (i.e. amphipods, copepods, rotfiers, etc.) which are living on the different matrix types.  Research to date has shown 3-dimensional matrices extruded from polypropylene produces significantly more biomass and has higher nutrient removal than other matrices tested.  The systems have also not experienced a production "crash", commonly experienced in outdoor microalgae culture, to date.  Based on this data, it is apparent that ATS systems can be easily optimized for cost efficient nutrient removal in many different commercial aquaculture settings.