Influences of natural zeolite on speciation of heavy metals during rotary drum composting of green waste
The research paper by Jiwan Singh and Ajay S. Kalamdhad investigates the impact of natural zeolite (clinoptilolite) on the speciation and bioavailability of heavy metals during the rotary drum composting of water hyacinth mixed with cattle manure and sawdust. The study addresses the challenge posed by heavy metals in water hyacinth compost, which can limit its application in agriculture due to potential toxicity.
The research employs the Tessier sequential extraction method to analyze the speciation of heavy metals (Zn, Cu, Mn, Fe, Pb, Ni, Cd, and Cr) throughout the composting process. The composting mixture was prepared in a 6:3:1 ratio of water hyacinth, cattle manure, and sawdust, with varying percentages (5%, 10%, and 15%) of natural zeolite added by weight. Key physicochemical parameters such as temperature, pH, and organic matter degradation were monitored.
Results indicated that the rotary drum composter effectively degraded organic matter, leading to a significant reduction in the bioavailable fractions of heavy metals, particularly the exchangeable and carbonate fractions. The addition of natural zeolite was found to enhance the immobilization of heavy metals, with the most significant reductions observed in the 10% zeolite treatment. The study concludes that the optimal use of natural zeolite can effectively reduce the bioavailability of heavy metals during composting, making the resulting compost safer for agricultural use.
This research paper is significant in the field of environmental science and waste management, particularly in the context of composting and soil remediation. It contributes to ongoing discussions about the safe recycling of organic waste, especially invasive species like water hyacinth, which can accumulate heavy metals. By demonstrating the effectiveness of natural zeolite in reducing heavy metal bioavailability, the study provides a practical solution for improving compost quality and safety. This research is beneficial for environmental engineers, waste management professionals, and agricultural scientists seeking sustainable practices for composting and soil enhancement.
