Solidification/stabilization of flue gas desulfurization brine and coal fly ash for heavy metals and chloride immobilization: Effects of S/S conditions and zero-valent-iron pretreatment
| Autor: | Ching-Hua Huang, Benjamin Gallagher, Kirk Ellison, Wenlong Zhang, Jay E. Renew, Harshad Oswal |
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| Rok vydání: | 2019 |
| Předmět: |
Environmental Engineering
Health Toxicology and Mutagenesis 0211 other engineering and technologies 02 engineering and technology 010501 environmental sciences engineering.material 01 natural sciences Chloride chemistry.chemical_compound Friedel's salt medicine Environmental Chemistry Waste Management and Disposal 0105 earth and related environmental sciences Lime 021110 strategic defence & security studies Zerovalent iron Chemistry Pollution Flue-gas desulfurization Brine Fly ash Environmental chemistry engineering Leaching (metallurgy) medicine.drug |
| Zdroj: | Journal of hazardous materials. 384 |
| ISSN: | 1873-3336 |
| Popis: | Effective management of flue-gas-desulfurization (FGD) wastewater and coal-combustion-residues (CCRs) are major challenges in the coal-fired power industry. The zero-liquid-discharge (ZLD) method of combining FGD brines and CCRs in solidification/stabilization (S/S) is promising due to its potential of treating both wastes in the same process. This study evaluated the performance of such a ZLD method for immobilizing heavy metals (Se, As, Cd and Cr) and chloride in FGD wastewater and/or CCRs. Effects of different coal fly ash (bituminous (BCFA) and sub-bituminous (SCFA)), activating agent (Portland cement (PC) and lime) and pretreatment of brines by zero valent iron (ZVI) on the S/S process were evaluated. Short-term and long-term leaching tests were conducted to evaluate performance of the S/S solids in pollutant retainment. The pre-treatment of FGD brine by ZVI enhanced the retainment of heavy metals when BCFA was used, but not when SCFA was used since it already performed quite well without ZVI pretreatment. Quantitative X-ray diffraction and scanning electron microscopy analyses strongly indicated the formation of Friedel’s salt, Ca2Al(OH)6(Cl,OH)·2H2O, is critical in the retainment of heavy metals and chloride. SCFA contained higher lime and reactive aluminate contents than BCFA; thus, S/S solids made with SCFA contained higher amounts of Friedel’s salt. |
| Databáze: | OpenAIRE |
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