The Lindbergh Foundation Believes that Innovative Science and Technology Hold the Key to Addressing Humanity’s Environmental and Productivity Challenges

Dr. Chad A. Kinney, Colorado State University, Pueblo, CO

“Using Earthworm Composting to Reduce Manmade Contaminants in Wastewater Biosolids Destined for Land Application”

Category: Waste Minimization and Management: 2009

In the U.S., the EPA estimates that more than 9 million dry tons of biosolids are produced annually. The practice of applying biosolids to the land is an affordable option for disposing of solid materials produced during wastewater treatment. The high content of organic matter also makes it an attractive soil amendment and a good source of plant nutrients. Recently, however, researchers discovered that applying biosolids to the land could introduce organic compounds like pharmaceuticals, synthetic fragrances, and disinfectants into the soil. Organic wastewater contaminants (OWC) can leach from the soil into groundwater, and some may accumulate in plant tissue, including crops. Earthworms in biosolid amended soil can accumulate OWCs, and songbirds, consuming those earthworms also may be affected. Dr. Kinney plans to investigate vermicomposting, a relatively new method for producing biosolids. The idea is that the normal metabolic activity of earthworms and the increase in bacterial activity associated with a high density of earthworms will significantly reduce the quantity of OWCs in the final biosolid product. If this proves to be effective, it will serve as a model approach to reduce the translocation of OWCs from wastewater treatment facilities into the land. The goal of this project is to provide scientific evidence for a biosolid production process that maintains the sustainable use of the organic rich nutrient source as a soil amendment, while protecting the natural environment and food and water supplies. In addition, increased use of biosolids produced from energy efficient vermicomposting will likely result in a net reduction in energy consumption compared to production of synthetic inorganic fertilizers.

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Final Report

The solid byproduct of wastewater treatment, sewage sludge or biosolids, is known to contain a complex mixture of anthropogenic organic contaminants (AOCs). Biosolids are commonly used as an organic carbon-rich source of nutrients on agricultural soil or as a soil amendment to promote plant regrowth in land reclamation projects. Vermicomposting proved to be effective at removing a substantial fraction of the AOCs included in the study in both laboratory (12 – 90%) and pilot scale (21 – 100%) tests. Currently the results of this study are being prepared for publication and dissemination in a peer reviewed scientific journal, with an expected submission date of late spring or summer 2011.

Read the Final Report