The neutralization behavior of MSWI bottom ash on different time scales and in different reaction systems

The neutralization behavior of municipal solid waste incineration (MSWI) bo ttom ash is characterized according to reaction time and reaction system. B atch and flow-through pH titrations are used to determine the acid neutrali zing capacity of the MSWI bottom ash in different reaction systems. A react ion path model and a reactive transport model evaluate the detailed mechani sms and titration kinetics of the experiments. The results indicate that bo th the neutralization kinetics and titration kinetics of the test methods a re important. They determine the relation between the time scale of the exp eriments and that of an actual leaching environment. Current pH titration e xperiments account mainly for the relatively fast neutralization reactions, so that they cannot assess the long-term neutralization processes of MSWI bottom ash. It is also found that the neutralization characteristics of MSW I bottom ash in a flow-through system are very different from those in a ba tch system. The movement of a pH front and the washing-out of soluble buffe ring components have large influences on the neutralization ability of MSWI bottom ash in a reaction system with flow-through of leachant. (C) 1999 El sevier Science Ltd. All rights reserved.