Usually when people see the words "algae" and "manure" in the same paragraph, it is usually a negative take on the effects of manure nutrients on water. When excess nutrients are transported to water bodies (from lawn fertilizer, municipal waste treatment plants, manure and/or commercial crop fertilizer) algae use those nutrients and grow rapidly. When the nutrients are no longer sufficient for growth, the algae begins to die and decompose. This depletes oxygen in the water, which can lead to fish kills and other problems for aquatic life.
The same characteristics of algae that can make it a nuisance also make it an innovative way to treat wastewater when grown in an engineered system. The fact that the algae are able to utilize the nutrients within the water to multiply and grow rapidly can be exploited within a managed system to create a potential source of biomass, and serve as a biological mechanism to remove nutrients. The sustained biological activity of algae can also add dissolved oxygen to the water, potentially reducing the direct emissions of methane and nitrous oxide (greenhouse gases) from volatilization of stored manure. Current research is exploring the use of harvested algae as an animal feed, source of biofuel (algal oil production), or biomass in thermal energy production.
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Author: Rick Field, University of Arkansas and Jill Heemstra, University of Nebraska
This information is part of the program “Integrated Resource Management Tool to Mitigate the Carbon Footprint of Swine Produced In the U.S.,” and is supported by Agriculture and Food Research Initiative Competitive Grant no. 2011-68002-30208 from the USDA National Institute of Food and Agriculture. Project website: http://www.extension.org/71201.