The recyclability of waste generated in Korea was determined by sampling ten kinds of sludge to analyze its chemical composition and organic content. We also analyzed the regulatory items for waste control laws and soil environmental laws. Investigation of the leaching property revealed that all sludge samples were classified as general waste and the sludge samples were not types of waste that are prohibited or restricted from being recycled. The S1 sample was evaluated as organic sludge upon measuring the organic content and finding it to be 40% or higher; the other samples were deemed inorganic. Organic sludge S2 exceeded the Zn in the second regional standard of soil environmental laws. Among the inorganic sludge samples, S2 and S8 were considered most likely to be recycled because there were no hazardous substances that exceeded the standard. However, they should be recycled safely after the evaluation of their recyclability according to the recycling purpose and method. Especially the S5 sample was deemed difficult to recycle because it exceeded the third regional standard, which is the highest soil standard.

Slag and coal ash were selected to evaluate the recyclability of waste generated during the heat treatment processes. A list of waste types and recyclable types of the two wastes were identified. A recycling environmental hazardous assessment was reviewed step by step. In addition, the hazardous properties of slag and coal ash were investigated, and the chemical components, leaching, and content of harmful substances in the waste were analyzed. The two selected wastes were classified as general wastes. As a result of chemical analysis with XRF, the two wastes did not produce toxic gases in contact with water and show leaching toxicity from the analysis of harmful substances. In addition, waste is often brought into contact with the soil when recycled, so the content of slag and coal ash is analyzed and compared with the 2 region standard of soil; two samples were within the standard. Therefore, the surveyed wastes can be recycled in non-matrix contact types and the recycling purpose and method permitted by the new law is excluded from the recycling environmental hazardous assessment. However, to recycle wastes for new uses, the recycling environmental hazardous assessment is required.

Raw and secondary waste materials from recycling products have been used to produce cements. A total of 10 cements produced from recycling products were analyzed for chemical composition, such as Na2O, MgO, Al2O3, SiO2, SO3, Cl, K2O, CaO, TiO2, Cr2O3, MnO, Fe2O3, CuO, ZnO, and PbO, using the Korean standard leaching test. The total content of toxic substances, such as Pb, Cd, Cu, As, Hg, and Cr(VI), present in each cement was also measured. The corrosion characteristics of cement leachates were also determined by measuring their pH values using an ion selective electrode and measuring the corrosion rate of a circular steel plate in each leachate. The chemical composition of the cements was found to be 60-67% CaO, 18-23% SiO2, and 5-6% Al2O3. Based on the results of the leaching tests, the samples did not exceed the prescribed regulatory leaching levels. The total content of toxic substances in each cement did not exceed the voluntary agreement criteria of 20 mg/kg. In the case of the corrosion characteristics of the cement leachates, the pH of each leachate was greater than 12.5 and the corrosion rate of a circular steel plate in each leachate did not exceed 6.35 mm/yr. The correlation between pH and the corrosion rate of steel in the solid waste leachates was difficult to determine.

A total of 15 different solid waste materials were analyzed for toxic substances such as Pb, Cd, Cu, As, Hg, Cr (VI)by the Korean standard leaching test and as total content. These wastes were also tested for corrosivity characteristicsusing an ionic electrode for pH and a circular steel for corrosion rate. Based on the results of the leaching test, the solidwaste samples did not exceed the regulated leaching levels. Thus, the analyzed wastes may be classified and managedas general industrial waste, not hazardous waste. Four solid waste samples were greater than total content levels proposedby other previous study. In case of the corrosive property of the solid waste leachate (1:2.5), the highest pH of the wastesample exhibited the lowest corrosion rate of 0.065mm/yr. However, the waste samples with low pH values exhibiteda greater corrosion rate. It is difficult to determine the correlation between pH and corrosion rate of the solid waste leachate.Therefore, the testing of the solid wastes are needed to further investigate the corrosion of a glass electrode method ratherthan the corrosion rate measurement. In the future, other hazardous properties such as ecotoxicity should be also examinedto properly manage the solid waste materials.