Cement based stabilization/solidification of organic contaminated hazardous wastes using Na‐bentonite and silica‐fume

Abstract

Cement‐based stabilization/solidification of hazardous wastes containing heavy metal and organic has been investigated using chrome tanning waste. This work investigated the use of bentonite and briquette ash as adsorbents for the organic components and heavy metals of industrial wastes, and silica‐fume as an admixture to improve the solidified wastes with cement. Chrome tanning wastes containing up to 1.5% organic carbon and 1.2% chromium were treated with sodium montmorilonite (bentonite) and briquette ash. Organic components and heavy metal of wastes were well adsorbed by the adsorbents. Solidification of the waste/clay/silica‐fume mixes produced a monolithic mass with high strength and very low leaching of the organic compounds and the metals. This study has shown that bentonite and briquette ash could be successful adsorbents for the organic contaminant and heavy metals in industrial wastes and enabled them to be treated by cement‐based solidification. Also the use of silica‐fume to get high compressive strength and low penetration was highly effective. Cement‐based solidification with the bentonite, briquette ash, and silica‐fume gave solid products which set rapidly and were far stronger and more homogeneous than the sole cement‐based solidification. Leaching organic and metal from the stabilized products were very low. The TOC was reduced by 60% to 78% for the wastes tested compared with the conventional cement‐based solidified waste, and the release of heavy metal was reduced by 52% to 70%.

Key words:

• Hazardous Wastes
• Solidification
• Leachability
• Chromium
• Silica fume
• Bentonite
• Mercury Intrusion Porosimetry