基于双侧阵列电极的电阻抗成像原位膜污染监测

In situ monitoring of membrane fouling by electrical impedance tomography based on bilateral array electrodes

基于电阻抗成像(electrical impedance tomography,EIT)技术设计了一种双侧阵列电极的膜污染原位监测装置,并应用于动态膜污染过程监测。通过模拟和实验比较了单侧和双侧电极阵列的成像效果。结果表明:电极双侧阵列方式依靠离子流动和外界电流产生额外电势差,监测更灵敏,重建图像与真实图像之间的相关系数0.89,能够更准确获得污染物信息。以高岭土、海藻酸钠(SA)和湖水为污染物,探究了不同污染物在超滤膜面的污染过程,得到了通量和膜污染成像图。结果表明,高岭土污染先集中于进水口附近,之后向中间区域和出水口迁移;湖水絮凝污染物主要分布在出水口附近;SA污染主要集中在进水口附近区域。建立了阻抗变化和污染物厚度之间关系,结果显示随厚度增大,阻抗变化增长速率也增大。

Based on electrical impedance tomography(EIT)technology,a membrane fouling in situ monitoring device with bilateral array electrodes was designed and applied to dynamic membrane fouling process monitoring.The electrode bilateral array method relies on the ion flow and external current to generate additional potential difference,which makes the monitoring more sensitive,and the correlation coefficient between the reconstructed image and the real image is 0.89,which enables more accurate information about the fouling to be obtained.Using kaolin,sodium alginate(SA)and lake water as model foulants,the different fouling characteristics of ultrafiltration(UF)membrane surface were explored,and flux changes and membrane fouling imaging were obtained.The results showed that kaolin was first concentrated near the inlet, and then migrated to the intermediate region and outlet,flocculated lake water was mainly distributed near the outlet, and SA was mainly concentrated in the inlet. Thequantitative relationship between impedance change and the thickness was obtained by reconstructing images fromEIT signals. The results showed that the rate of growth of impedance change values increased with increasingthickness.