垃圾焚烧飞灰中重金属的传统与生物电沉积联用技术研究

为了探究深圳市城市生活垃圾焚烧飞灰中主要重金属含量和浸出浓度, 选择浸出浓度超标的Cu(II) (100 mg/L), Pb(II) (200 mg/L) 和Zn(II) (300 mg/L)作为研究对象, 联合生物电化学系统(BES)和传统电沉积反应器(ER), 验证从飞灰浸出溶液中分离回收Cu, Pb和 Zn的可行性和经济性。研究结果表明, BES能有效地将混合溶液中的Cu(II)还原为单质, 去除效率大于98%。分步施加1.5 V和2.5 V 外加电压, ER可以分别将Pb(II)和Zn(II)浓度由200和300 mg/L降至23.5±1.1和4.3±0.2 mg/L。系统能耗分析结果显示, BES系统每还原1 kg Cu(II), 可以产生16.55 kWh的额外电能, ER系统每处理1 kg Pb(II)和Zn(II), 分别消耗60.91和114.27 kWh的电能, 溶解性重金属离子被转化为固态单质、氧化物和含重金属盐等。BES和ER联用技术表现出回收重金属和节约电能的双重优势。

A Study on the Electro-and-bioelectro-deposition of Heavy Metalsin Municipal Solid Waste Incinerator Fly Ash

The contents and leaching concentrations of heavy metals from municipal solid waste incinerator (MSWI) fly ash were investigated in Shenzhen. Targeting at Cu, Pb and Zn as the key heavy metals, aqueous solutions containing Cu(II), Pb(II) and Zn(II) of 100 mg/L, 200 mg/L and 300 mg/L were synthesized to test the feasibility and efficiency of electro-and-bioelectro-deposition of heavy metals. In a bio-electrochemical system (BES), the removal and recovery efficiency of Cu(II) was >98%. In the subsequent electro-deposition reactor (ER), the concentrations of Pb(II) and Zn(II) were decreased from 200 and 300 mg/L to 23.5±1.1 and 4.3±0.2 mg/L with external voltage of 1.5 and 2.5 V, respectively. Energy consumption analysis revealed that extra electricity of 16.55 kWh was generated by 1 kg Cu(II) reduction in BES, while electricity of 60.91 kWh and 114.27 kWh were consumed by 1 kg Pb(II) and Zn(II) treatment in ER, and the heavy metal ions were reducted to free elements, oxides and salts. These results suggest that a combined BES and ER technology has advantages in metal recovery and energy saving.