污水深度处理中超滤工艺对有机物的截留模型

Modeling organics rejection during ultrafiltration in advanced wastewater treatment

基于浓差极化现象和膜孔堵塞效应,建立了污水深度处理中超滤工艺对有机物的截留模型.利用中试试验数据率定模型参数并验证模型的模拟效果.模型验证结果表明,该模型能够较好地模拟超滤工艺出水UV254值随时间的变化特征,基于最优参数得到的模拟值与相应实测值相对误差的绝对值均低于10%.并且模型参数区域灵敏度分析和不确定性分析结果表明,该模型的结构具有较高的可靠性.应用该模型研究了过滤时间、通量和进水浓度变化对出水水质的影响.结果表明,在过滤初期膜孔堵塞效应占主导地位并增加超滤膜对有机物的截留效果,在过滤后期浓差极化现象占主导地位并降低超滤膜对有机物的截留效果;当进水UV254浓度恒为0.1cm-1时,通量从5×10-5m/s增至1×10-4m/s,导致UV254截留率降低13%;当通量恒为5×10-5m/s时,进水UV254浓度从0.2cm-1降至0.1cm-1,使得出水浓度降低50%.因此,模型可应用于模拟进水水质和操作条件对污水深度处理中超滤工艺出水水质的影响,为从预处理、过滤周期和通量等方面改进和优化超滤工艺提供基础.

Based on the concentration polarization theory and pore blocking effect,a model was developed to predict organics rejection during ultrafiltration in advanced wastewater treatment. The model was calibrated and validated against data collected from pilot-scale experiments. Results of model validation indicated that the model could well predict the time variations of permeate UV254 during ultrafiltration with absolute relative errors between simulated and observed data less than 10%. Regional sensitivity analysis and uncertainty analysis of model parameters suggested that the model exhibit a robust and reliable structure. The influence of different operating conditions,including filtration time,flux and feed concentration,on permeate concentration was investigated with the developed model. Results indicated that the pore blocking effect dominated in the initial stage of ultrafiltration and increased the rejection rate of organics,whereas concentration polarization effect dominated the rest and decreased rejection. The rejection rate of UV254,with a constant feed concentration of 0.1cm-1,was decreased by 13% when the flux increased from 5×10^-5 m/s to 1×10^-4m/s. With a constant flux of 5×10^-5m/s,however,the permeate UV254 concentration was 50% lower at a feed concentration of 0.1cm^-1than that at 0.2cm^-1. Therefore the model could simulate the influences of influent quality and operating conditions on effluent quality for the ultrafiltration process in advanced wastewater treatment,and thus provide decision support for the optimization of ultrafiltration with respect to pretreatment,filtration period and flux.