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SOLIDIFICATION/STABILIZATION OF SLUDGE AND ASH FROM WASTEWATER TREATMENT PLANTS
Citation:
Malone, P. AND L. Jones. SOLIDIFICATION/STABILIZATION OF SLUDGE AND ASH FROM WASTEWATER TREATMENT PLANTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-85/058 (NTIS PB85207504), 1985.
Description:
Tests were performed to determine the physical properties and chemical leaching characteristics of the residuals and the stabilized/solidified products from two publicly-owned wastewater treatment works (POTW). The two POTW waste products included in this study were an anaerobic digester sludge from an Imhoff digester and an ash from a rotating hearth incinerator used to destroy primary settler and digester sludges. Three different solidification/stabilization systems were used. One of the systems was based on the addition of cement and soluble silicates in various proportions and formed soil-like solids that were soft and easily broken. A second system used lime and flyash to form a pozzolanic material that produced a hard, concrete-like solid. The third system was based on the formation of gypsum in the waste after acidification; these products remained wet and did not harden. None of the treated products were very durable, as none survived the full sequence of 12 cycles and the wet-dry or freeze-thaw testing. The pozzolanic, flyash-lime product reduced the loss of constituents to the leaching medium to the greatest extent. It also produced by far the smallest increase in the weight of the waste to be disposed for any of the processes--170% of the dry sludge solids. These facts coupled with the low cost of the solidification agents make this process the most cost-effective of those tested in this study.