Influences of natural zeolite on speciation of heavy metals during rotary drum composting of green waste
AbstractThe presence of heavy metals in water hyacinth compost is the main limiting factor for its land application. Water hyacinth can accumulate heavy metals in its tissues. Application of natural zeolites (clinoptilolite) during water hyacinth composting may be helpful to immobilise heavy metals. The present study was carried out on the speciation of heavy metals (Zn, Cu, Mn, Fe, Pb, Ni, Cd and Cr) during rotary drum composting of water hyacinth mixed with cattle manure, sawdust and natural zeolite. The Tessier sequential extraction method was used for heavy metal speciation determination. The water hyacinth, cattle manure and sawdust at a ratio of 6:3:1 ratio was mixed with 5, 10 and 15% natural zeolite by weight. Influences of physicochemical parameters such as temperature, pH and organic matter degradation on speciation of heavy metals were studied during the process. A rotary drum composter has been shown to be highly efficient for organic matter degradation. The most bioavailable fractions (exchan...