Using Biosolids and Slag Sand for Habitat Restoration
Aquatic Research Institute
East Chicago, IN
Through the combined efforts of a Department of Energy national laboratory, a nonprofit organization, a city government, a public high school, a steel company, and a metropolitan sanitary district, two unattractive waste products may soon be used to beautify an urban landscape.
The City of East Chicago, Indiana, needed a cost-effective way to reclaim the many brownfields that blight its landscape, and asked the Aquatic Research Institute (ARI), a nonprofit organization, to develop initiatives to solve this problem. ARI needed scientific expertise in land remediation, and so turned to Argonne National Laboratory.
The concept of improving the fertility of slag sand, an environmentally benign by-product of steel-making, by combining it with a nutrient-rich material, such as the biosolids that result from water treatment, was a natural. Northwest Indiana is home to several steel companies and the Sanitary District of East Chicago operates a water treatment plant, so the waste materials could be obtained locally at no cost. The steel industry and the sanitary district would also benefit – they would no longer have to deal with disposal of these waste products.
To evaluate the feasibility of this concept, Argonne developed an experimental program to test different combinations of the two waste products as a growth medium for various plants. Students from East Chicago's Central High School performed the research under Argonne's supervision, as part of an associated environmental education program. The results confirm that sand slag and biosolids can be mixed to form a soil-like substrate that can support plant life and aid in the remediation of brownfields. Expansion of this initial program is planned for the near future.
The new concept combines two waste products so that they can support plant life and aid in restoration of brownfields. Slag sand, a by-product of the steel-making process, is currently disposed of by open stacking on the surface of the soil. Decades of this practice has resulted in slag sand being the top layer of "soil" in many areas. Although environmentally benign, slag sand does not contain enough nutrients to support plant life and contributes to creation of brownfields. However, if its fertility could be increased, slag sand could be converted into a soil-like substrate and the land could be reclaimed for beneficial use.
Biosolids result from wastewater treatment. They are currently disposed of by landfilling, incineration, surface disposal, and land application (e.g., as fertilizer on agricultural land). Biosolids are an excellent source of nitrogen, phosphates, and other plant nutrients. These two waste products can be combined in different ratios to form a substrate that can support growing plants. This substrate can either be left in place on the original site, or it can be added to existing soil in other areas to increase fertility. This process would both eliminate the need for waste disposal by reusing industrial by-products and provide a way to remediate otherwise unusable land by using no-cost materials. The feasibility of this concept has been proven in laboratory experiments.
The work was performed under a Technical Services Program (TSP) Agreement. The TSP is supported by the Department of Energy, Office of Science, Laboratory Technology Research Program.
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