Effects of Natural Zeolites on Bioavailability and Leachability of Heavy Metals in the Composting Process of Biodegradable Wastes
The chapter investigates the role of natural zeolites, specifically clinoptilolite, in reducing the bioavailability and leachability of heavy metals during the composting of biodegradable wastes, particularly water hyacinth and sewage sludge. Heavy metals such as Zn, Cu, Mn, Fe, Ni, Pb, Cd, and Cr pose significant environmental risks when present in compost, as they can leach into soil and water, potentially entering the food chain.
The authors conducted experiments using two composting methods: Agitated Pile Composting (APC) and Rotary Drum Composting (RDC). They measured the water solubility, DTPA-extractability, and leachability of heavy metals, finding that the addition of natural zeolite significantly reduced these parameters. Specifically, the presence of zeolite increased the concentrations of beneficial cations (Na, Ca, K) while decreasing the bioavailable fractions of heavy metals.
The study highlights that the optimal addition of zeolite (5-10%) during composting enhances organic matter degradation and stabilizes the compost, making it safer for land application. The results indicate that zeolite effectively reduces the water-soluble and DTPA-extractable fractions of heavy metals, thus mitigating their potential toxicity. The chapter concludes that incorporating natural zeolite into composting processes can be a viable strategy for managing heavy metal contamination in organic waste recycling.
This chapter is significant in the field of environmental science and waste management, particularly in the context of composting and soil health. It contributes to ongoing discussions about sustainable waste management practices by providing empirical evidence on the effectiveness of natural zeolites in reducing heavy metal toxicity in compost. The findings are beneficial for researchers, policymakers, and practitioners involved in waste management, agriculture, and environmental protection, as they offer a practical solution to enhance compost quality and safety for agricultural use. The chapter underscores the importance of addressing heavy metal contamination in compost to protect human health and the environment.
