Yuma pretreatment lime sludge could make concrete mix
The US Bureau of Reclamation announced on 21 September 2011 that its Yuma area office in Arizona is entering into a cooperative research and development agreement with Envirock Inc to explore whether sludge from the Yuma desalination plant can be used in a new "green" concrete mix formulation.
A successful project could reduce operating costs of the Yuma plant, on the Arizona- Mexico border, by up to US$ 245,000/ 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 US$ 1 million/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 & 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 US 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 US Environmental Protection Agency estimates that water treatment facilities dispose of 6.8 million t/y of sludge solids.