The incorporation of untreated or Mg-modified natural zeolite in municipal solid waste compost has been shown to reduce heavy metal concentration of corn plants growing in the remediated soil.
A primary negative result of municipal waste composts is the contamination of soils with heavy metals. Management of the composted soil must be conducted before any land application in order to prevent heavy metal uptake by plants. Total uptake of Pb, Cu, Mn, Zn, Ni, and Cd was studied in corn plants, grown in remediated soil, with and without the addition of different natural zeolite.
A greenhouse experiment tested the potential effects of composts containing natural zeolite on the distribution of heavy metals in corn plants. Natural zeolite was added to the municipal solid waste at the starting of the composting process at 5%, 10% and 15% by volume. The solid waste was processed to a size less than 60mm. The waste was mixed with zeolites at different ratios and the composting process was performed for two months. Compost was mixed every three days.
At harvest, the heavy metals were measured in the compost and corn plants.
The application of natural zeolite in the composting process resulted in a significant reduction of heavy metals.
The concentrations of heavy metal in root, stalk, and leaves of corn plants are shown in Fig. 3. Remarkable differences in heavy metal concentration were found among the treatments. Increasing the zeolite dosage … in applied compost significantly reduced most of the heavy metals concentrations in corn roots, stalks and leaves compared to C treatment. (Page 4)
Amount decreased of DTPA-extractable Pb, Cu, Zn, Mn, Ni and Cd in matured compost:
Natural Zeolite: 13%, 44%, 22%, 32%, 28% and 29% in comparison to zeolite-free compost. Mg modified zeolite: 14%, 47%, 25%, 36%, 43% and 36%, respectively. Mg- modified zeolite was more effective than natural zeolite, but not significantly.