Papers by Keyword: Heavy Metal Leaching

Abstract: Dried sludge could be used for brick production by firing with shale or clay, which would reduce clay resource exploitation and realize sludge resource utilization. Physical and mechanics parameters of fired shale-sludge brick and clay-sludge brick are tested to examine technical feasibility, and heavy metal leaching concentrations are tested to examine brick safety. The results show that after municipal sludge in Changsha Wastewater Treatment Plant is dried with water content no more than 30%, it can be used for shale-sludge brick and clay-sludge brick firing and qualified produces can be produced. Compressive strength of brick is 10-20 MPa, there is no scum and lime crack on brick body. Under high firing temperature, heavy metal in sludge can be solidified, and leaching concentrations can meet the requirements. By doing so, calorific power of sludge can be utilized and energy saving can be realized.

Abstract: Municipal Solid Waste Incinerator (below MSWI) ash is used to develop inorganic binder for preparing geopolymer concrete in this study. Toxic substituents, such as heavy metals are de-toxificated by above-mentioned new solidity technique. Slag and coal fly ash are used as active filler to enhance compressive strength. MSWI ash was mixed with slag and coal fly ash to make geopolymer concrete. They were solidified under alkali condition and dried at 50°C and 80°C, respectively. Compressive strength was measured to evaluate the characteristics of specimens for the period of 3, 7 and 14 days. Compressive strength measurements show a maximum strength of almost 13.7 MPa after 14 days. The mineral phases of specimen were analyzed by XRD. And the morphology was analyzed by the photo of SEM. The micro-structure of inorganic binder prepared was analyzed by FTIR. Korea Standard leaching Test (KSLT) and TCLP method are used to the environmental safety of inorganic binder. Raw FA measured concentrations of Cu and Pb were 0.30 ppm and 28.31 ppm, respectively. Leaching amounts of heavy metal were noticeably reduced after the solidification of MSWI as with active filler. It is possible to de-toxificate MSWI ash by new solidity techniques. And it may be used as alternative concrete.

Abstract: Stabilizing characteristics of heavy metals in the silicate glass (SD) and lead silicate glass(PD) containing Electric Arc Furnace(EAF) dust was studied by the toxic characterization leaching procedure(TCLP) test. Dependence of the amount of EAF dust upon structural changes of SD and PD glasses and TCLP results was also investigated by FT-IR spectroscopy. In the TCLP test, the concentration of heavy metals leached from a glass increased with the amount of EAF dust added. The SD series specimens showed heavy metal leaching lower than the PD series specimens, but the Pb leaching from the PD series specimens was the highest owing to the high Pb content in the PD glass composition. The value R(oxygen/network former ion ratio) was used to compare the leaching characteristics of glasses, and the SD had a higer R than PD series specimens to show a better chemical durability. Adding the EAF dust to the SD mother glass decreased the Si-O-Si symmetry and increased the non-bridging oxygen, which weakened the structure and decreased the chemical durability of glasses. It is concluded that SD is more effective in stabilizing the heavy metals of EAF dust than PD series glass.