Current status and perspectives of accelerated carbonation processes on municipal waste combustion residues

The increasing volumes of municipal solid waste produced worldwide are encouraging the development of processes to reduce the environmental impact of this waste stream. Combustion technology can facilitate volume reduction of up to 90%, with the inorganic contaminants being captured in furnace bottom ash, and fly ash/APC residues. The disposal or reuse of these residues is however governed by the potential release of constituent contaminants into the environment. Accelerated carbonation has been shown to have a potential for improving the chemical stability and leaching behaviour of both bottom ash and fly ash/APC residues. However, the efficacy of carbonation depends on whether the method of gas application is direct or indirect. Also important are the mineralogy, chemistry and physical properties of the fresh ash, the carbonation reaction conditions such as temperature, contact time, CO₂ partial pressure and relative humidity. This paper reviews the main issues pertaining to the application of accelerated carbonation to municipal waste combustion residues to elucidate the potential benefits on the stabilization of such residues and for reducing CO₂ emissions. In particular, the modification of ash properties that occur upon carbonation and the CO₂ sequestration potential possible under different conditions are discussed. Although accelerated carbonation is a developing technology, it could be introduced in new incinerator facilities as a “finishing step” for both ash treatment and reduction of CO₂ emissions.     

气相色谱-火焰光度法测定土壤中有机磷农药残留

土壤样品用正己烷-丙酮(体积比为1∶1)混合溶液提取,配合硅胶小柱净化,用乙酸乙酯洗脱,再用气相色谱-火焰光度法测定待测液中14种有机磷农药残留,方法在0.100 mg/L~1.00 mg/L范围内线性良好,当取样量为10 g时,方法检出限为1.3μg/kg~2.3μg/kg。用该方法测定有机磷的有证标准溶液,结果均在保证值范围内,RSD为2.2%~6.7%。实际土壤样品的13种有机磷农药加标回收率为59.2%~125%(敌百虫除外),敌百虫回收率为0,说明目标物在测定过程中被降解,该方法不适用于敌百虫的测定。     

Influence of surfactant sorption on the removal of phenanthrene from contaminated soils

Laboratory column flushing experiments were conducted to remove phenanthrene from contaminated soils by Triton X-100 (TX100) with an aim to investigating the effect of surfactant sorption on the performance of surfactant-enhanced remediation process. The effluent concentration of phenanthrene from soil columns showed strong dependence on the sorption breakthrough curves of TX100. The removal of phenanthrene from contaminated soils was enhanced only when the sorption breakthrough of TX100 occurred and the influent concentration of TX100 was greater than the critical enhanced flushing concentration (CEFC). The sorption of surfactant onto soils and the subsequent partitioning of contaminants into soil-sorbed surfactant had a significant effect on the solute equilibrium distribution coefficient (KD) and thus the flushing efficiency for phenanthrene. A model was developed to predict KD and CEFC values for simulating the performance of surfactant-enhanced flushing for contaminated soils. These results are of practical interest in developing effective and safe surfactant-enhanced remediation technologies.