COMPARATIVE-ASSESSMENT OF ACCELERATED LEACHING METHODS FOR ON-SITE VERIFICATION TESTING OF SPECIAL WASTE

Time-consuming leaching test procedures, like the German standard DIN 38 414-4, are not suited for rapid on-site waste and soil assessment. Thus, different kinds of accelerated leaching methods are individually applied, often without appropriate validation. With the use of two ty pical samples, we investigated various leaching methods (shaking, stir ring, vortexing, heating, percolation, sonication, and microwave irrad iation:) with regard to comparability and repeatability. Leachate conc entrations of summaric parameters, metals, and anions were determined. After a leaching period of only 5 min, most of the experiments gave r esults representing 50% or more of the corresponding DIN results. The best-suited methods achieving more than 85% recovery for all analytica l parameters were either ultrasonic agitation or vortexing, depending on the sample. With regard to repeatability, vortexing was the most pr ecise method comparable to the DIN procedure. An ultrasonic-accelerate d leaching method that has regularly been applied at a special waste d isposal facility for rapid waste identification was then systematicall y compared to the DIN standard procedure. Recoveries within 20 min wer e 60-85% compared to concentrations in DIN leachates. The average prec ision of the accelerated method was found to be 8% and the precision o f the standard method was 5%. (C) 1998 John Wiley & Sons, Inc.