Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
Water Res. 2012 Jun 15;46(10):3272-82. doi: 10.1016/j.watres.2012.03.020. Epub 2012 Mar 23.
River water was treated by ultrafiltration at a relatively low transmembrane pressure (40 mbar). As observed before, flux stabilization occurred after several days of operation although no back-flushing or cross flow was applied. Interruptions in flux were applied by temporary offset of the transmembrane pressure. After restoration of the transmembrane pressure, the initial flux was higher than the stable flux level, and the flux recovery depended on the standstill time. Furthermore, if a short cross flow was applied after standstill, the flux was restored to an even higher level. In all cases, the flux decreased again during operation to reach finally the same stable level as before standstill. In order to evaluate the influence of intermittent operation as practiced for water treatment on a household level, daily interruptions of flux were applied. An optimum of total daily water production rate was obtained at 21 h of operation and 3 h of standstill per day. A model was developed which can describe the impact of intermittent operation on the flux depending on the duration of the standstill and operating periods. This enables the prediction of production capacity of the system operated intermittently. The flux increase during standstill could be explained by a relaxation and expansion of the biofouling layer, while the higher flux after forward-flushing was caused by this layer being partially sloughed off. Household water treatment with the process presented here will generally be operated on a discontinuous basis. The results show that such operation schemes do not compromise the permeability of the system, but actually lead to higher fluxes after standstill.
河水在相对较低的跨膜压力（40 毫巴）下通过超滤进行处理。正如之前观察到的，尽管没有进行反冲洗或错流，通量稳定在几天的运行后发生。通量的中断是通过暂时偏移跨膜压力来实现的。在恢复跨膜压力后，初始通量高于稳定通量水平，通量恢复取决于停止时间。此外，如果在停止后短暂地进行错流，则通量会恢复到更高的水平。在所有情况下，通量在运行过程中再次下降，最终达到与停止前相同的稳定水平。为了评估间歇操作作为家庭水处理的实际应用对通量的影响，每天都进行通量中断。每天运行 21 小时，停止 3 小时，可获得最佳的总日产水量。开发了一种模型，该模型可以根据停止和运行时间的持续时间来描述间歇操作对通量的影响。这使得可以预测间歇操作的系统的生产能力。停止期间通量的增加可以通过生物污垢层的松弛和膨胀来解释，而正向冲洗后的更高通量是由于该层部分剥落所致。家庭用水处理采用本文介绍的方法通常将以不连续的方式运行。结果表明，这种操作方案不会降低系统的渗透性，反而会在停止后导致更高的通量。
