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Growing Algae on Landfill Sludge at University of Florida

July 19, 2011, by Jonathan Williams
AlgaeIndustryMagazine.com

esearchers at the University of Florida are looking at ways to grow algae in landfill leachate, or the coffee colored liquid sludge that pools at the bottom of landfills as the waste decomposes. Landfill operators are responsible for this waste even after the landfill has closed and have to typically pay large amounts of money to dispose of it properly. However, with algae, landfill leachate could have some intrinsic value.

Scott Edmundson, a graduate student working with Dr. Ann Wilkie at the University of Florida, presented his findings at the 1st International Conference on Algal Biomass, Biofuels, and Bioproducts, this week in St. Louis, on how well algae can grow in this waste. His research focused on a landfill that had been in operation from 1988 to 1999 in Archer, a small town outside Gainesville, FL. According to their research, this one landfill contains over 3 million gallons of leachate and the landfills in Florida produce an average of 770 gallons/acre/day.

After sampling local algae strains found around the landfill site, they tested growing algae in various dilutions of leachate. They discovered that in every dilution of leachate algae will grow, even in “pure” leachate. The strain of algae typically differs depending on the dilution level but in each case, at least one species seems to thrive. Edmundson believes the success of growing algae in leachate can be traced to the high amounts of nutrients that it contains, particularly nitrogen in the form of ammonia.

Because of the nature of the growth media, lipid-based biofuels are the main products being looked at from these algae. After lipid extraction, the remaining biomass can be used for anaerobic digestion to produce methane. To harvest algae from the growth containers, Edmundson’s team is using simple settling methods that rely on gravity.

At this point, several species of algae with high levels of lipids have been identified as successfully growing in various leachate dilution levels. Research is set to continue and looks to scale up the levels of algae growth using leachate.

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