Leaching behavior of heavy metals from cement derived from the co-burning of hazardous waste

Abstract

Burning of hazardous waste in cement kiln is the new technology based on waste-derived and alterative fuels. Besides being the alternative way to destroy hazardous waste, this method provides alternative material as raw material or the fuel in the cement production process. This disposal method can be applied if the contaminant either does not appear in the emission or leach from cement to environment. This research focused on the leaching behavior of heavy metals from cement. The studied havy metals were chromium, zinc, and nickel. To study the leaching behavior, Microwave-assisted leach method 3051A, Availability leaching test (NEN 7341), and pH static leach test were used. Results showed that chromium and zinc were likely to be leached from the cement that more than 80% of them can be leached to the environment. In contrast, approximately 3% of nickel can be leached to environment. From the pH static leach test, chromium was effectively leached at pH range 4-10. Zine and nickel were effectively leached at pH 4 and the leachability of them decreased when the pH increased. In this research, Toxicity characteristic leaching procedure (TCLP) and Notification of Ministry of Industry No.6 B.E. 2540 were also used to identify the cement as hazardous waste or non-hazardous waste. The results showed that raw material doped with chromium more than 0.1 wt.%, the cement was classified as hazardous waste. In contrast, the raw material doped with nickel and zinc up to 2 wt.%, the cement was not classified as hazardous waste.