The extended understanding of how silicates from coal combustion products (CCPs) can be tailored for use in specific chemical stabilization of trace elements in wastes and wastewater has been expanded via use patents and actual practice over the last decade. The past ASTM E2060 guide focused on CCP use with arsenic, barium, boron, cadmium, chromium, cobalt, lead, molybdenum, nickel, selenium, vanadium, and zinc. Chemical stabilization may be accompanied by solidification of treated wastes. Solidification is not a requirement for the stabilization of many trace elements but does offer advantages in waste handling and in reduced permeability of the stabilized waste. Solidification is an importan factor in treatment of wastes and especially wastewaters. Solidification/Stabilization (S/S) technology is often used to treat wastes containing free liquids. This new work item addresses new environmentally sound uses of CCPs as a stabilizing agent without the addition of other materials; however, stabilization or chemical fixation may also be achieved by using combinations of CCPs and other products such as lime, lime kiln dust, cement kiln dust, cement, catalysts and polymers. CCPs used alone or in combination with other reagents promote stabilization of many inorganic constituents through a variety of mechanisms. These mechanisms include precipitation as carbonates, silicates, sulfates, and so forth; microencapsulation of the waste particles through pozzolanic reactions; formation of metal precipitates; and formation of hydrated phases. The wastes or wastewater, or both, containing the problematic inorganic species will likely be highly variable, so the chemical characteristics of the waste or wastewater to be treated must be determined and considered in the selection and application of any stabilizing agent, including CCPs. In any waste stabilization process, laboratory-scale tests for compatibility between the candidate waste or wastewater for stabilization with one or more selected CCPs and final waste stability are recommended prior to full-scale application of the stabilizing agent.
Developed by Subcommittee: E50.03
Staff Manager: Molly Lynyak
Date Initiated: 04-01-2022
Technical Contact: Benjamin Gallagher
Ballot: E50 (22-12)
Status: At Society Review