4. Conclusion
The study analyzed & presented the concentration of heavy
metal, PAH distribution and leaching characteristics of hazardous
waste among various thermal processing units in South Korea.
The analysis result concludes:Iron & steel thermal (IS) process
showed the highest median value for Hg (2.38 mg/kg) in content
as well as in the leachate (0.646 mg/L). The raw material selection
in IS is an important criteria to reduce the Hg content in
waste because the source of Hg in IS are raw materials. Compared
to all the heavy metals, Zn median concentration present
in the waste (83.02–31,419 mg/kg) and leachate concentration
(BDL–397.7 mg/L) was much greater in almost all the thermal metallurgies.
The leachate concentration of Zn in six samples exceeded
the hazardous waste landfill limits. Due to their high leaching characteristics
of Zn in the waste, it can be extracted using selective
dissolution before disposal. Most of the Zinc thermal metallurgy
(ZnM) samples showed high median concentrations of many heavy
metals. Two samples of ZnM neither suitable for non-hazardous
nor hazardous landfill criteria. ZnM needs effective treatment and
disposal strategy.Total PAH concentrations in sludge & filter cakes
of CuM (37.72 mg/kg) and NFe (46.25 mg/kg) were comparatively
higher than any other process. PbM, ZnM and NFe samples neither
posses the PAH limits of ocean dumping as per Korean standard
nor EU standards for land applications. Comparatively leaching
of heavy metals was more in the flue gas dust (FGD) rather than
other forms of waste irrespective of the concentration present in
the waste. So it can be recommended to consider the use of FGD
as a raw material in hydrometallurgical processes to recover the
possible metals instead of direct disposal.