Simulated Infinite-Dilution Leach Test

Abstract

This paper introduces the Simulated Infinite Dilution Reactor (SIDR) Leaching Test as a replacement for conventional dynamic leaching tests based on ANS 16.1. Conventional leaching tests underestimate leaching rates for contaminants that are at low concentrations in the porewater of the waste by failing to maintain infinite dilution conditions in the leaching solution. To circumvent this problem, SIDR incorporates an ion exchange resin suspended in its leaching solution, which keeps contaminant concentrations at sufficiently low levels so that they do not affect the rate of leaching. Results from SIDR are consistent with theoretical expectations that predict that the cumulative amount of contaminant leached is linearly related with the square root of leaching time. Procedures based on ANS 16.1 underestimate D _obs by a factor of 20 for Pb and 60 for Cd compared to results obtained using the SIDR Leach Test.