(523a) Algal-Based Bioremediation of Landfill Leachate

Landfill leachate is a wastewater that can cause chronic and acute toxicity because it contains various inorganic and organic wastes. There are 3,000 active landfills and 10,000 or more inactive or closed landfills across the United States. The majority of leachate is co-treated in publicly owned treatment works (POTW). This requires the collection and transportation of the leachate from the landfill sites to the POTWs. Depending on the landfill characteristics, the leachate contributes 50 to 2500 mg ammoniacal nitrogen L^-1 additional load to the POTWs. . However, this method is considered unsustainable due to various water quality and regulatory issues. Therefore, it is vital to develop sustainable, cost-effective on-site leachate treatment technologies focusing on near and longer-term contaminant issues. In this research study, we evaluated the potential of using thermophilic mixotrophic algae, Galdieria sulphuraria (GS), to efficiently perform on-site treatment of leachate. We experimentally determined the growth rates of GS in various dilutions of actual municipal landfill leachate samples, and evaluated the nutrient and removal rates in 1L and 15L algal bioreactors. Based on the results, the growth reactors with 20% landfill leachate outperformed the other growth reactors in terms of final biomass density and nutrient removal rates. The final algal biomass density in 20% landfill leachate was 2.34 g L^-1, which is more than twice as in standard Cyanidium medium (CM) with 1.10 g L^-1, and the observed growth rate was 175 mg L^-1 d^-1. Ten-day removal efficiencies were 99.0% for ammoniacal-nitrogen and 42% for phosphate. Removal rates were 24.56 mg L^-1 d^-1 of ammoniacal-nitrogen and 2.65 mg L^-1 d^-1 of phosphate. Overall, this study showed encouraging laboratory-scale and pilot-scale data for an algal-based treatment system for municipal landfill leachate samples.