Evoluzione della sostanza organica nel percolato di discariche per rifiuti industriali

We examine the results of the characterization made on two MSWI bottom ash release test carried out on sample representative of 6 months of plant operation. Beyond the mineralogical, chemical, and particle-size characterization, we investigate in detail the release of heavy metals, both by first level characterization with pH static-test and by II level compliance test. The release was estimated also on the single dimensional class fraction. The behaviour of two ashes is similar and the influence of different total metals quantity is sensible only at the extreme values of pH. The effect of the pH is much obvious for the amphoteric metals (Al, Pb, Zn) whereas the particle size is the only macroscopic factor that influence the release of Cu. The final pH of the leachate is function of the dimensional class considered and the leaching test. We even observe some change in the release with distilled water (test UNI 10802) between the humid ash, as taken just after quenching in water, and the ash let exposed to the air for a time in between some hours to weeks. For the lead there is a strong drop of the final concentration in the leachate. We interpret this effect with carbonation of the bottom ash