In this study, an effective circulating system was developed to remove heavy metals in medical waste incineration (MWI) fly ash. MWI fly ash (MWIFA)-column experiments were performed to remove Cu, Pb, Zn, Cd, and Ni from MWIFA using EDTA disodium (Na₂EDTA). Iron-column experiments were conducted to study the removal effect of zero-valent iron on the five heavy metals from washing wastewater. Toxicity Characteristic Leaching Procedure (TCLP) test method was employed to evaluate heavy metals toxicity of MWIFA residues generated after 0–0.2 mol/L Na₂EDTA solution treated. After being washed by 0.2 mol/L Na₂EDTA solution, TCLP leaching values of Cu, Pb, Zn, Cd, and Ni were the lowest and satisfied the standard (GB 5085.3–2007), and the leaching values were 58.4 ± 2.0 mg/L, 2.81 ± 0.14 mg/L, 64.3 ± 4.0 mg/L, 0.156 ± 0.005 mg/L, 0.381 ± 0.006 mg/L. Concentrations of Cu, Pb, Zn, Cd, and Ni in iron-column effluent were reduced by 99.7%, 91.6%, 91.6%, 75.4%, and 75.7%, respectively. Na₂EDTA was recovered and recycled to the removal of heavy metals from MWIFA. Comparing new Na₂EDTA solution with recycled Na₂EDTA solution, recycled Na₂EDTA and water could be reutilized to dispose MWIFA. The removal efficiencies of Cu, Pb, Zn, Cd, and Ni by recycled 0.2 mol/L Na₂EDTA solution were 67.1%, 68.8%, 63.2%, 73.9%, 50.7%, respectively, the removal efficiencies using recovered Na₂EDTA decreased by 2.6%, 3.9%, 3.3%, 4.2%, and 1.6%, respectively. Successive batch experiments were also conducted to evaluate industrialization potential and reusable times for recycled Na₂EDTA. After four recirculation cycles, extraction efficiencies of Pb and Cd (removal efficiency at different cycles divided by removal efficiency of new Na₂EDTA) declined toward 80%. Results from this research indicated that this circulating system possessed industrialization potential.

Implications: An effective circulating system was developed to remove heavy metals in MWI fly ash (MWIFA). Integration of Na₂EDTA with Fe⁰ promoted the removal of heavy metals from MWIFA. Na₂EDTA, NaCl and water were stepwise extracted from iron-column effluent, respectively. Recovered Na₂EDTA can still effectively remove heavy metals from MWIFA. Results from this research indicated that this circulating system possessed industrialization potential.

在这项研究中，开发了一种有效的循环系统以去除医疗废物焚烧（MWI）粉煤灰中的重金属。使用EDTA二钠（Na ₂ EDTA）进行MWI粉煤灰（MWIFA）柱实验，从MWIFA中去除Cu，Pb，Zn，Cd和Ni 。进行了铁柱实验，研究了零价铁对洗涤废水中五种重金属的去除效果。毒性特征浸出程序（TCLP）测试方法用于评估0–0.2 mol / L Na ₂ EDTA溶液处理后产生的MWIFA残留物的重金属毒性。用0.2 mol / L Na ₂洗涤后EDTA溶液中，Cu，Pb，Zn，Cd和Ni的TCLP浸出值最低且满足标准（GB 5085.3–2007），浸出值为58.4±2.0 mg / L，2.81±0.14 mg / L， 64.3±4.0 mg / L，0.156±0.005 mg / L，0.381±0.006 mg / L。铁塔流出物中的铜，铅，锌，镉和镍的浓度分别降低了99.7％，91.6％，91.6％，75.4％和75.7％。回收Na ₂ EDTA，并将其循环用于从MWIFA中去除重金属。将新的Na ₂ EDTA溶液与回收的Na ₂ EDTA溶液进行比较，可以将回收的Na ₂ EDTA和水重新利用以处置MWIFA。循环0.2 mol / L Na ₂去除Cu，Pb，Zn，Cd和Ni的效率EDTA溶液分别为67.1％，68.8％，63.2％，73.9％，50.7％，使用回收的Na ₂ EDTA的去除效率分别降低了2.6％，3.9％，3.3％，4.2％和1.6％。还进行了连续的批生产实验，以评估回收的Na ₂ EDTA的工业化潜力和可重复使用时间。经过四个循环后，Pb和Cd的萃取效率（不同循环的去除效率除以新的Na ₂ EDTA的去除效率）下降至80％。这项研究的结果表明，这种循环系统具有工业化潜力。

含义：开发了有效的循环系统以去除MWI粉煤灰（MWIFA）中的重金属。Na ₂ EDTA与Fe ^0的结合促进了MWIFA中重金属的去除。从铁柱流出物中逐步提取Na ₂ EDTA，NaCl和水。回收的Na ₂ EDTA仍然可以有效地去除MWIFA中的重金属。这项研究的结果表明，这种循环系统具有工业化潜力。