采油污水对离子交换膜的污染研究

Study on fouling of ion exchange membranes used for oil-field wastewater

为了缓解油田污水对离子交换膜的污染程度,使电渗析技术更好地用于油田污水处理,从而实现含聚合物采油污水的良性循环,针对含聚采油污水对离子交换膜的污染情况进行了考察.实验考察了相同工况下,淡室溶液电导率下降到0.9mS·cm-1所经历的时间、平均电流和膜面电阻等参数的变化,确定了离子交换膜的污染状况,分别考察了含聚合物采油污水中的固体悬浮物、聚合物和原油对离子交换膜性能的影响.实验结果表明,部分固体悬浮物集聚在阴离子交换膜和阳离子交换膜表面甚至内部从而造成膜污染,但相对于阴膜,悬浮物对阳膜性能的影响更严重;聚合物可聚集在阴膜表面,对于阴膜的透过性有一定的影响;原油在阴膜表面甚至内部形成致密的油膜,对其造成严重污染,但对阳膜的影响较小.利用酸碱液以及非离子表面活性剂(AEO-9)作为清洗剂,并添加少量的助洗剂(如三聚磷酸钠),阴膜过滤能力可以得到有效恢复.

In order to reduce the fouling of ion exchange membranes used to treat oilfield wastewater, electrodialysis technology was applied to achieve benign circulation of polymer-flooding oilfield wastewater. Parameters including elapsed time, average current, and membrane surface resistance were measured under the same operating conditions until the electrical conductivity of dilute solution decreased to 0.9 mS· cm^ -1. The fouling status of the ion exchange membrane was investigated. The effects of suspended solids, polymer, and crude oil in the oilfield wastewater on the performance of ion exchange membranes were studied. The experimental results show that suspended solids collected on the surfaces of, and even inside, both anionic and cationic membranes, producing fouling, but the effect was greater on the cationic membrane. The polymer may congregate on the surface of anion membrane, which influences the permeation of the anionic membrane; and crude oil can form a compact oil film on the surface of, and even inside, the anionic membrane, which results in severe fouling, but these mechanisms have less effect on the cationic membrane. The first, acid and alkali is utilized to clean the anionic membrane. The second, the membrane is cleaned by non-ionic surfactant （ AEO-9）, and adding a small quantity of a washing aid （such as STPP）, the anionic membrane could be restored effectively.