| 氨对垃圾焚烧飞灰浸出特性的影响及地球化学模拟 |
| 摘要点击 1940 全文点击 913 投稿时间：2012-08-24 修订日期：2012-10-29 |
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| 中文关键词 氨泄漏 选择性非催化还原法 焚烧飞灰 重金属浸出 Visual MINTEQ |
| 英文关键词 ammonia slip selective non-catalytic reduction(SNCR) incineration fly ash heavy metals leaching Visual MINTEQ |
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| 中文摘要 |
| 垃圾焚烧飞灰可能因为选择性非催化还原法(SNCR)脱硝过程中氨泄漏、垃圾携带的渗滤液受热挥发等原因而吸附氨. 本研究中采用人为添加氨水,在 pH为3.66~12.44范围内,研究氨对飞灰中溶解性有机碳(DOC)和重金属浸出的影响,并利用地球化学模拟软件Visual MINTEQ从金属化学形态分布上分析氨对飞灰浸出的影响机制. 结果表明,DOC在pH>9和有高浓度氨(≥1357 mg·L-1)存在时,其浸出量大幅增加,而在浸出液中氨的水平不高于537 mg·L-1时则受氨的影响很小; 在pH<6时,飞灰中各金属主要以自由态的金属离子和金属-氯络离子形态大量溶出,且受氨的影响较小; 而在pH 为8~12的碱性环境中和氨浓度较高时(≥3253 mg·L-1),氨与金属生成了可溶性的金属-氨配合物,能显著增加Cd、Cu、Ni、Zn的浸出,且在pH=9附近时浸出量达到最大值,但氨对Al和Pb的浸出影响甚微; 在pH>12时,Cd、Cu、Ni、Zn主要以羟基金属离子形式存在. 在氨浓度为3253 mg·L-1时,通过利用Visual MINTEQ模拟浸出值与试验数据的对比,发现Al、Pb、Zn的浸出主要由溶解/沉淀模型控制,而Cd、Cu、Ni由溶解/沉淀模型和表面吸附反应模型同时控制,且Visual MINTEQ模型能较好地预测飞灰中Al、Cu、Pb、Zn的浸出特性. |
| 英文摘要 |
| Incineration fly ash could be contaminated with NH3 that was slipped from the ammonia-based selective non-catalytic reduction(SNCR) process and from evaporation of municipal solid wastes' leachate involved in the wastes. This research was conducted to investigate the impacts of ammonia on leaching of dissolved organic carbon (DOC) and metals from incineration fly ash in the pH range of 3.66-12.44 with an active ammonia spike. A geochemical modeling software Visual MINTEQ was adopted to calculate the chemical speciation of metals under the leaching conditions to reveal the mechanism behind the impacts. It was proved that at pH>9, the leaching of DOC increased significantly in the presence of high concentrations of ammonia (≥1357 mg·L-1), but there was little effect when the ammonia level in eluates was not higher than 537 mg·L-1. At pH<6, metals in fly ash were released mainly in the form of free metal ions and chloride complexes, which were little influenced by ammonia; while at pH 8-12, higher concentrations of ammonia (≥3253 mg·L-1) mobilized Cd, Cu, Ni and Zn significantly due to the formation of soluble metal-ammonia complexes, and the leaching rates reached their peaks at pH around 9; however, ammonia had little impacts on Al and Pb leaching within this pH range. At pH>12, for Cd, Cu, Ni and Zn, their leaching species were predominantly in the form of hydroxide complexes. Under the ammonia concentration of 3253 mg·L-1, the Visual MINTEQ modeling results were compared with the experimental data, and it was proved that the leaching of Al, Pb and Zn was mainly controlled by precipitation/dissolution modeling, while Cd, Cu and Ni were controlled by precipitation/dissolution and surface complexation/precipitation processes; Visual MINTEQ modeling could well describe the leaching behaviors of Al, Cu, Pb and Zn from incineration fly ash. |
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