[Effect of sodium carbonate assisted hydrothermal process on heavy metals stabilization in medical waste incinerator fly ash].
A sodium carbonate assisted hydrothermal process was induced to stabilize the fly ash from medical waste incinerator. The results showed that sodium carbonate assisted hydrothermal process reduced the heavy metals leachability of fly ash, and the heavy metal waste water from the process would not be a secondary pollution. The leachability of heavy metals studied in this paper were Cd 1.97 mg/L, Cr 1.56 mg/L, Cu 2.56 mg/L, Mn 17.30 mg/L, Ni 1.65 mg/L, Pb 1.56 mg/L and Zn 189.00 mg/L, and after hydrothermal process with the optimal experimental condition (Na2CO3/fly ash dosage = 5/20, reaction time = 8 h, L/S ratio = 10/1) the leachability reduced to < 0.02 mg/L for Cd, Cr, Cu, Mn, Ni, Pb, and 0.05 mg/L for Zn, according to GB 5085.3-2007. Meanwhile, the concentrations of heavy metals in effluent after hydrothermal process were less than 0.8 mg/L. The heavy metals leachability and concentration in effluent reduced with prolonged reaction time. Prolonged aging can affect the leachability of metals as solids become more crystalline, and heavy metals transferred inside of crystalline. The mechanism of heavy metal stabilization can be concluded to the co precipitation and adsorption effect of aluminosilicates formation, crystallization and aging process.
Jin
Jian
J
State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China. jacky4000@163.com
Li
Xiao-dong
XD
Chi
Yong
Y
Yan
Jian-hua
JH
D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry*; D060729:Coal Ash; D004355:Drug Stability; D006358:Hot Temperature; D017745:Incineration; D017744:Medical Waste Disposal / Q000379:methods*; D019216:Metals, Heavy / Q000737:chemistry*; D052638:Particulate Matter / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D000393:Air Pollutants; D002254:Carbonates; D060729:Coal Ash; D017744:Medical Waste Disposal; D019216:Metals, Heavy; D052638:Particulate Matter; D014867:Water; C005686:sodium carbonate; D002244:Carbon