The processes and techniques of stabilization/solidification (S/S) have matured into an accepted, and important, part of environmental technology. As a result, a great many S/S methods have been promoted recently and offered for the treatment of hazardous and other wastes from industry, municipalities, and government sources. The purpose of this article is review these methods critically in light of the current regulatory atmosphere that controls and often mandates their use. An overview of the technology is provided. The generic and proprietary S/S processes (chemical processes, physical processes, and thermal processes) are described. Of these, six generic chemical processes dominate the field and encompass nearly all of the treatment work and proprietary products to date: Portland cement, cement/fly ash, cement/soluble silicate, lime/flyash, kiln dust, and phosphate. Current and anticipated major waste streams using S/S technology today are summarized. The S/S approach for each of these are reviewed. F...

A Critical Review of Stabilization/Solidification Technology

The processes and techniques of S/S matured into an accepted, and important, part of environmental technology How this came about is both interesting and instructive for those working this discipline as well as others fascinated by a technical area that is still part art and part science With few exceptions, the history of S/S for use on hazardous waste residues dates only from about 1970, when the EPA was established Most of the impetus for S/S of hazardous wastes was provided when the Resource Conservation and Recovery Act was passed in 1976, although real implementation did not occur until after 1980 with the promulgation of regulations for a Federal hazardous waste management system under Subtitle C of RCRA With the passage of the HSWA in 1984 and the subsequent LDR regulations beginning in 1985, and CERCLA and SARA and their regulations, most of the present regulatory system came into being The most recent, and far reaching, ramifications of regulation with respect to S/S are due to the Land Dis

The History of Stabilization/Solidification Technology

https://clu-in.org/download/contaminantfocus/mercury/advances-in-encapsulation-600r02081.pdf

Advances in encapsulation technologies for the management of mercury-contaminated hazardous wastes ☆

The present invention provides a composition and process for disposal of radioactive, hazardous and mixed wastes. The present invention preferably includes a process for multibarrier encapsulation of radioactive, hazardous and mixed wastes by combining substantially simultaneously dry waste powder, a non-biodegradable thermoplastic polymer and an anhydrous additive in an extruder to form a homogenous molten matrix. The molten matrix may be directed in a "clean" polyethylene liner, allowed to cool, thus forming a monolithic waste form which provides a multibarrier to the dispersion of wastes into the environment.

Composition and process for the encapsulation and stabilization of radioactive, hazardous and mixed wastes

Sulfur polymer solidification/stabilization of elemental mercury waste.

Modified sulfur cement encapsulation of mixed waste contaminated incinerator fly ash

The majority of solidification/stabilization systems for low-level radioactive waste (LLW) and mixed waste, both in the commercial sector and at Department of Energy (DOE) facilities, utilize hydraulic cement (such as portland cement) to encapsulate waste materials and yield a monolithic solid waste form for disposal. A new and innovative process utilizing modified sulfur cement developed by the US Bureau of Mines has been applied at Brookhaven National Laboratory (BNL) for the encapsulation of many of these problem'' wastes. Modified sulfur cement is a thermoplastic material, and as such, it can be heated above it's melting point (120{degree}C), combined with dry waste products to form a homogeneous mixture, and cooled to form a monolithic solid product. Under sponsorship of the DOE, research and development efforts at BNL have successfully applied the modified sulfur cement process for treatment of a range of LLWs including sodium sulfate salts, boric acid salts, and incinerator bottom ash and for mixed waste contaminated incinerator fly ash. Process development studies were conducted to determine optimal waste loadings for each waste type. Property evaluation studies were conducted to test waste form behavior under disposal conditions by applying relevant performance testing criteria established by the Nuclear Regulatory Commission (formore » LLW) and the Environmental Protection Agency (for hazardous wastes). Based on both processing and performance considerations, significantly greater waste loadings were achieved using modified sulfur cement when compared with hydraulic cement. Technology demonstration of the modified sulfur cement encapsulation system using production-scale equipment is scheduled for FY 1991. 12 refs., 8 figs., 3 tabs.« less

Comparison of modified sulfur cement and hydraulic cement for encapsulation of radioactive and mixed wastes

A polyethylene process for the improved encapsulation of radioactive, hazardous, and mixed wastes have been developed at Brookhaven National Laboratory (BNL). Improvements in waste loading and waste form performance have been demonstrated through bench-scale development and testing. Maximum waste loadings of up to 70 dry wt % mixed waste nitrate salt were achieved, compared with 13--20 dry wt % using conventional cement processes. Stability under anticipated storage and disposal conditions and compliance with applicable hazardous waste regulations were demonstrated through a series of lab-scale waste form performance tests. Full-scale demonstration of this process using actual or surrogate waste is currently planned. A scale-up feasibility test was successfully conducted, demonstrating the ability to process nitrate salts at production rates (up to 450 kg/hr) and the close agreement between bench- and full-scale process parameters. Cored samples from the resulting pilot-scale (114 liter) waste form were used to verify homogeneity and to provide additional specimens for confirmatory performance testing.

Polyethylene encapsulation of mixed wastes: Scale-up feasibility

Some of the process waste streams incinerated at various Department of Energy (DOE) facilities contain traces of both low-level radioactive (LLW) and hazardous constituents, thus yielding ash residues that are classified as mixed waste. Work is currently being performed at Brookhaven National Laboratory (BNL) to develop new and innovative materials for encapsulation of DOE mixed wastes including incinerator ash. One such material under investigation is modified sulfur cement, a thermoplastic developed by the US Bureau of Mines. Monolithic waste forms containing as much as 55 wt % incinerator fly ash from Idaho national Engineering Laboratory (INEL) have been formulated with modified sulfur cement, whereas maximum waste loading for this waste in hydraulic cement is 16 wt %. Compressive strength of these waste forms exceeded 27.6 MPa. Wet chemical and solid phase waste characterization analyses performed on this fly ash revealed high concentrations of soluble metal salts including Pb and Cd, identified by the Environmental Protection Agency (EPA) as toxic metals. Leach testing of the ash according to the EPA Toxicity Characteristic Leaching Procedure (TCLP) resulted in concentrations of Pb and Cd above allowable limits. Encapsulation of INEL fly ash in modified sulfur cement with a small quantity of sodium sulfidemore » added to enhance retention of soluble metal salts reduced TCLP leachate concentrations of Pb and Cd well below EPA concentration criteria for delisting as a toxic hazardous waste. 12 refs., 4 figs., 2 tabs.« less

P. Colombo

Papers

Modified sulfur cement encapsulation of mixed waste contaminated incinerator fly ash

Comparison of modified sulfur cement and hydraulic cement for encapsulation of radioactive and mixed wastes

Polyethylene encapsulation of mixed wastes: Scale-up feasibility

Encapsulation of mixed radioactive and hazardous waste contaminated incinerator ash in modified sulfur cement