铋改性沸石粉强化超滤膜性能的研究

Improvement of ultrafiltration membrane properties by bismuth-modified powdered zeolite

为进一步提高超滤工艺对废水深度处理效果、减缓超滤膜污染,研究提出铋改性沸石粉强化超滤(Bi-Z-UF),并对铋改性沸石粉投加量、粒径和反冲洗频率进行优化以获得高效的强化效果。结果表明:(1)相比直接超滤和天然沸石粉强化超滤,Bi-Z-UF更能有效减缓膜通量下降速率,经过3个过滤周期,膜反冲洗后几乎能恢复到初始膜通量。(2)Bi-Z-UF对污水处理厂二级出水中COD、254nm处吸光度(UV254)和TN的去除率最高分别可达26%、23%和16%。(3)铋改性增加了沸石的吸附活性中心,在超滤膜表面形成了疏松有孔的"保护层",能减少污染物与超滤膜直接接触,有利于减缓膜通量下降速率,并促进对污染物的吸附、截留与去除,强化了超滤膜性能。

In order to further improve the advanced treatment effectiveness of wastewater by ultrafiltration and reduce the membrane fouling rate,an efficient technique to enhance the industrial performance via bismuth-modified powdered zeolite(Bi-Z-UF)was proposed.The dosage,particle size of bismuth-modified powdered zeolite and backwash frequency were optimized for further improving the membrane performance.The results showed that:(1)compared to direct ultrafiltration and ultrafiltration with powdered zeolite,Bi-Z-UF had the most significant effect on reducing the membrane fouling rate.After 3 cycles of operation,the membrane flux was recovered well after backwashing.(2)The removal rates of COD,UV254 and TN in secondary effluent by Bi-Z-UF were up to 26%,23%and 16%,respectively.(3)The adsorption active centers of zeolite were increased by introducing bismuth element.A loose and porous covering layer was formed on the ultrafiltration membrane surface,which could hinder the direct contact between pollutants and the ultrafiltration film,reduce the decline rate of membrane flux,and promote the removal of pollutants by adsorption,retention and degradation.