重庆市垃圾焚烧飞灰中重金属分布特征及药剂稳定化处理

Distribution and chemical stabilization of heavy metals in municipal solid waste incineration fly ash of Chongqing

采用在飞灰药剂处理中研究广泛的硫化钠、磷酸二氢钠、乙硫氮、丁铵黑药、3,4,6-三巯基均三嗪三钠盐作为稳定化药剂,将重庆市某垃圾焚烧发电厂产生的飞灰作为研究对象,探究单一药剂及3种药剂的复合稳定化效果,并使用正交实验确定3种药剂的复合稳定化最优方案.结果表明,重庆市垃圾焚烧飞灰粒径主要集中在48—1700μm之间;飞灰中Cu、Pb、Zn、Cd、Hg均大幅超出环境土壤背景值;处于880—1700μm、250—880μm,150—250μm、75—150μm、48—75μm各粒径级的飞灰的Cu、Zn、Pb、Cd、Cr元素形态分布与混合样品的形态分布情况一致;单一药剂稳定化飞灰实验中,使得飞灰浸出浓度满足《生活垃圾填埋场污染控制标准》的药剂添加量分别为8%的硫化钠、8%的磷酸二氢钠、4.2%的乙硫氮、4.2%的丁铵黑药、4.2%的3,4,6-三巯基均三嗪三钠盐,其中,8%的硫化钠药剂成本最低;正交实验中的复合药剂稳定化均有良好的稳定化效果,其中1.2%的硫化钠、1.2%的磷酸二氢钠、0.8%的丁铵黑药的组合比单一药剂稳定化所需投加量更少、成本更低.

Using sodium sulfide,sodium phosphate,sodium diethyl dithiocarbamate,ammonium dibuyl dithiophosphate,tri-mercarpto-S-triazinetrisodium salt as chemical stabilization agents to treat the fly ash from a waste incineration power plant in Chongqing,this study aimed to find an optimal stabilization method for fly ash with single or mixture agents. The results showed that the particle size of MSWI fly ash was mainly distributed in the range of 48—1700 μm. The contents of Cu,Pb,Zn,Cd and Hg in the fly ash were significantly higher than their corresponding soil background values.The speciation of Cu,Zn,Pb,Cd,Cr in the particles in the size distribution of 880—1700 μm,250—880 μm,150—250 μm,75—150 μm,and 48—75 μm,is identical to that of the mixed sample. In the single agent stabilization experiment,8% sodium sulfide,8% sodium phosphate,4.2% DDTC,4. 2% ammonium dibuyldithiophosphate,4. 2% the tri-mercarpto-S-triazinetrisodium salt could all lower the leaching concentration of fly ash to meet the Control Standard of Municipal Solid Waste Landfill,and 8% sodium sulfide reagent had the lowest cost among them. All the chemical composite had good stabilization effect,and the best combination of 1.2% sodium sulfide,1.2% sodium phosphate and 0. 8% ammonium dibuyldithiophosphate is cheaper and more effective than the single reagent.