Generalized Acid Neutralization Capacity Test

A method is developed to measure the neutralizing capacity of various generic binders. The method, termed the generalized acid neutralization capacity (GANC) test, is based on modifications to Environment Canada Method No. 7, Acid Neutralization Capacity, combined with U.S. Environmental Protection Agency (EPA) Method No. 1311, Toxicity Characteristic Leaching Procedure. The GANC test is a single batch procedure that utilizes leachants normally ranging in acidity from 0 to 6 equivalents of acid per kilogram of solids. After 48 h of contact, the pH of the leachate is measured. The leachate can also be analyzed for alkalinity, hardness, and metals concentration. Plotting pH values versus equivalents per kilogram of solids defines the alkaline behavior of a sample. The more equivalents a binder neutralizes, the greater its buffering capacity and effectiveness in diminishing metals mobility, but too much alkalinity can also be harmful. Examples are given of the application of GANC test results and concepts to metal-spiked samples and to lead-contaminated soils from a Superfund site.