Reduced Utilization Process Leaching Toxicity by Stabilizing Heavy Metals in Fly Ash from MSW Incineration Based on...

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Fly ash from municipal solid waste incineration poses environmental risks due to heavy metal leaching.
• Effective stabilization of heavy metals is crucial for safe fly ash utilization.
• Hydrothermal oxidation is a promising treatment method for hazardous waste stabilization.

Purpose of the Study:

• To investigate the effects of hydrothermal oxidation parameters on heavy metal stabilization in fly ash.
• To determine optimal conditions for reducing heavy metal leaching toxicity.
• To evaluate the role of a Ce-Mn catalyst in the stabilization process.

Main Methods:

• Studying the impact of temperature, reaction time, pH, and Ce-Mn catalyst dosage.
• Analyzing heavy metal leaching concentrations before and after treatment.
• Characterizing the transformation of heavy metal fractions within the fly ash matrix.

Main Results:

• Higher temperatures positively correlated with improved heavy metal stabilization.
• Reaction time and pH showed unstable effects on stabilization.
• Ce-Mn catalyst enhanced stabilization at low doses but was inhibitory at high doses.
• Optimal parameters ensured heavy metal leaching met China's National Wastewater Discharge Standard (GB 8978-1996).
• Heavy metals shifted to more stable residue fractions, notably Cu and Zn, reducing overall toxicity.

Conclusions:

• Hydrothermal oxidation is an effective method for immobilizing heavy metals in MSW fly ash.
• Optimizing temperature and catalyst dosage is key to maximizing stabilization efficiency.
• The transformation of heavy metals into residue fractions significantly mitigates leaching risks, enabling safer fly ash utilization.