城市垃圾焚烧飞灰重金属药剂配伍稳定化实验研究
Experimental study of the stabilization of heavy metals in municipal solid waste incineration fly ash by chemical agent matching
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摘要: 以飞灰中富含的Pb和Zn为目标重金属,对飞灰中重金属药剂配伍稳定化效果了实验研究。选用EDTA、Na2S、NaH2PO4等稳定化药剂和pH值控制,首先将试剂单独投加飞灰中测定重金属浸出浓度,分析各试剂的稳定化效果;然后通过系列试验观察现象,确定试剂最优投加顺序;最后,按照试剂性质制定4个配伍方案,按照最优投加顺序投加试剂,测定分析各个配伍方案的稳定化效果。结果表明:pH值保持在弱碱性(10左右),重金属稳定化效果较好。EDTA二钠、NaH2PO4和Na2S重金属稳定化效果明显,而有机试剂EDTA二钠稳定化效果明显优于NaH2PO4和Na2S;稳定化药剂投加顺序以Na2S、EDTA二钠、NaH2PO4顺序投加处理效果为最佳;配伍方案4处理效果明显优于其他方案,可以实现稳定化药剂配伍相合,提高飞灰中重金属稳定化效果,同时减少有机螯合剂的使用量,从而降低处理成本。Abstract: With taking heavy metals Pb and Zn as the target heavy metals, three agents of EDTA, Na2S and NaH2PO4 and pH value control are used to explore the efficiency of chemical agents to limit the leaching of heavy metals from fly ash. At first the agents are added into fly ash at a specific rate separately and the stabilization efficiency at a specific mass ratio to fly ash can be obtained through measuring the leaching concentration of heavy metals; then, through series experiments and sediment observation, the sequence of adding agents can be optimized; finally, based on the property of chemical agents, 4 plans of agent matching are made. After adding agents in the optimal adding sequence, the leaching concentrations of heavy metals are measured and the stabilization efficiency of each matching plan can be analyzed. It can be concluded that: when pH value stays at 10, the stabilization of heavy metals will be easier. EDTA, NaH2PO4 and Na2S can stabilize a large part of heavy metals in fly ash, and EDTA has a better efficiency than the other two in terms of the stabilization of heavy metals in fly ash; the stabilization efficiency will be the best when adding the agents in the sequence of Na2S, EDTA and NaH2PO4; the matching plan 4 has an much better stabilization of heavy metals Pb and Zn than other plans. The stabilization is much improved; meanwhile the treatment cost can be decreased by saving the usage of EDTA.
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Key words:
- municipal solid wastes /
- fly ash /
- incineration /
- heavy metals /
- harmless treatment /
- chemical agents
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