AWWA WQTC62587

The objective of this research is to incorporate a backwash in a standardizedsmall scale laboratory test in order to distinguish between the cake build up duringfiltration and the remaining fouling after repeated backwashes. The research is partof AWWARF Project 2952. In this project the results of natural organic matter (NOM) characterization,bench scale tests and pilot tests are compared in order to discoverparameters which are useful in full scale situation and in optimization. The Kiwa-test (mini-UF test) uses rather simple and inexpensive equipment which mimics the filtration and backwash cycles of the full-scale and pilot plants. Theequipment uses a four-way-valve to switch between filtration and backwash. On thepermeate-side of the membrane a storage of about 35 ml is used to store permeatefor the backwash. The pump is a piston pump with two 50 ml syringes. One syringeis filling and one is emptying all the time. The pump provides a constant flowindependent from the resistance of the ultrafiltration membrane. The flow is free ofpulses. The module uses is a small module potted by Filtrix with commercialcapillaries from different companies. The membrane surface area is about 0.0125msup2/sup. The modules are inexpensive (about 25 euro) so they can be disposed aftereach measurement. A typical experiment lasts for 6 hours. The flux during theexperiment is high (120 l/(msup2/sup.h)) to observe fouling during thisshort period. The backwash flux is the same because the pump-velocity is notchanged during an experiment. The water is pre-filtered over a 1.2 micron filter. Thepressure is measured as a function of time. About 15 liters of water is used for oneexperiment. The temperature is always 20 C. Includes 4 references, tables, figures.



Keywords: Backwash; Membranes; Equipment; Fouling; Ultrafiltration; Natural Organic Matter