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Lower Colorado Region
Boulder City, Nev.
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Doug Hendrix
(928) 343-8145
Peter Soeth
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Released On: September 21, 2011

Reclamation Enters CRADA with Envirock, Inc. to Explore Recycling of Lime Sludge into 'Green' Concrete
The Bureau of Reclamation's Yuma Area Office is entering into a cooperative research and development agreement (CRADA) with Envirock, Inc. to explore whether sludge from the Yuma Desalting Plant (YDP) can be used in a new "green" concrete mix formulation. The mix is designed to incorporate industrial waste products into a concrete that is expected to be lighter and stronger than commercially available formulations. The sludge consists primarily of calcium carbonate, which is used as a soil supplement on farm fields in some parts of the United States.

A successful project could reduce YDP operating costs by up to $245,000 per year. The plant uses lime in its pretreatment operations, and at full capacity can generate up to 131,000 tons of lime sludge per year. Reclamation maintains a system to dispose of this sludge, so if a process is developed to reuse it, the agency could avoid future costs of disposal, as well as costs to expand or rehabilitate the disposal facilities. The annualized capital savings could exceed $1 million per year.

The technology being evaluated is a type of cement which can contain/recycle up to 95% of a wide variety of industrial and post-consumer waste streams such as raw filler materials, including lime sludges, sewage sludges, brines, mercury wastes, Class C and F fly ash, and wood wastes. Part of the agreement includes Reclamation's Materials Engineering and Research Laboratory in Denver mixing samples into various formulations and then testing the formulations for durability and wearability.

Should the project be viable, it could more broadly benefit the nation's water treatment industry by helping to reduce operating costs and improve sustainability. Lime softening is used extensively in water treatment processes and is estimated to add 7-10% to the cost to treat the water. The U.S. Environmental Protection Agency estimates that water treatment facilities dispose of 6.8 million tons a year of sludge solids.

Assuming an Olympic-sized swimming pool holds 600,000 gallons, enough sludge is produced each year to fill 28,300 pools. Finding a way to recycle these waste materials into a commercially marketable resource can reduce the volume of material that needs to be disposed, enhancing the sustainability of water treatment technologies and helping Reclamation to achieve its water delivery mission and obligations.

To learn more about Reclamation's Research and Development Program, please visit http://www.usbr.gov/research and to learn more about how Reclamation is addressing advanced water treatment research needs, see http://www.usbr.gov/research/AWT.

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Reclamation is the largest wholesale water supplier and the second largest producer of hydroelectric power in the United States, with operations and facilities in the 17 Western States. Its facilities also provide substantial flood control, recreation, and fish and wildlife benefits. Visit our website at www.usbr.gov.