In a new study, scientists at Rice University have found that high value strains of oil-rich algae, which can be used as a feedstock for algae-based biofuels, can remove more than 50% of phosphorus and 90% of nitrates from wastewater. Working in collaboration with the Houston Department of Public Works and Engineering, the scientists operated a pilot-scale treatment system at a Houston’s wastewater treatment plant.
Though biofuels were an extremely popular topic a few years ago, much of the interest waned as “industry moved toward producing higher-value, lower-volume products for pharmaceuticals, nutritional supplements, cosmetics and other products” according to the study’s lead author Meenakshi Bhattacharjee. Producers are heavily dependent on chemical fertilizers which both reduces profit margins for algae producers and creates a competition with food producers. A 2012 National Research Council report found that “with current technologies, scaling up production of algal biofuels to meet even 5 percent of U.S. transportation fuel needs could create unsustainable demands for energy, water and nutrient resources.”
If wastewater can replace the chemical fertilizers, the cost of producing the biofuels will decrease. Additionally, the algae feeding off the wastewater would metabolize nitrates and phosphorus, two highly regulated pollutants in waterways.
Very little research had been performed to determine which process would be prefered by producers which yield specific products. The scientists at Rice began running a pilot-scale system of 12 open-topped 600-gallon tanks in July 2013. The tanks received primary effluent from the plant’s primary clarifiers. Multiple formulations of algae were tested in each tank, including both monocultures of oil-rich algal strains and mixed cultures. Some even included local algal strains from Houston bayous. Others contained fish that preyed upon algae-eating zooplankton. It appears the tanks which had monocultures cultures and without predatory fish outperformed the others, though there was significant growth in every tank tested.
View the full study below!
Source: Rice University