陶瓷膜处理含镍电镀废水

Treatment of electroplating wastewater containing nickel ions with ceramic membranes

研究了平均孔径分别为0.8μm和0.5μm的陶瓷膜对含镍电镀废水在p H为9时的微滤过程,考察了操作时间、跨膜压差、错流速度、温度和浓缩因子对膜通量和镍截留率的影响,探究了陶瓷膜的清洗行为及该微滤过程的数学模型。结果表明:随操作时间延长,膜通量先迅速下降,然后基本不变;随跨膜压差增大或错流速度增大,膜通量上升至趋于稳定;温度升高使得膜通量增大。0.8μm膜适宜操作参数为跨膜压差0.12 MPa、错流速度3.0 m/s和温度30℃;0.5μm膜适宜操作参数为跨膜压差0.14 MPa、错流速度3.4 m/s和温度30℃。在浓缩过程中,膜通量快速下降至平缓阶段,再较快降低,镍截留率约为99%;采用质量浓度0.15%盐酸清洗,0.8μm污染陶瓷膜能使其通量恢复到新膜通量的98%,而0.5μm污染陶瓷膜能恢复到新膜通量的97.5%;该微滤过程符合修正后的完全堵塞数学模型。

The microfiltration processes of electroplating wastewater containing nickel ions were studied with ceramic membranes with average pore diameters of 0. 5 μm and 0. 8 μm at p H 9. The effects of operating time,trans-membrane pressure,cross-flow velocity,temperature,and volume concentration factor on permeate flux and nickel rejection were investigated. Next,the cleaning of fouled membranes was studied,as was the mathematical model of the microfiltration process. The results showed that with increasing operating time,permeate fluxes decreased rapidly to a steady value. Steady-state fluxes were enhanced with increasing trans-membrane pressure or cross-flow velocity,and then remained constant. Steady-state fluxes were enhanced with increasing temperature.Optimum operating parameters for the 0. 8 μm membrane were trans-membrane pressure of 0. 12 MPa,cross-flow velocity of 3. 0 m / s,and temperature of 30 ℃. Optimum operating parameters for the 0. 5 μm membrane were trans-membrane pressure of 0. 14 MPa,cross-flow velocity of 3. 4 m / s,and temperature of 30 ℃. In the process of concentration,permeate fluxes decreased to a steady value and then decreased rapidly,and the nickel rejections were about 99%. Permeate fluxes could be recovered effectively to new membrane fluxes of 98% for a 0. 8 μm membrane and 97. 5% for a 0. 5 μm membrane by using 0. 15% hydrochloric acid. In addition,the modified completely blocked model can describe the microfiltration processes.