Cleaning of membranes fouled by proteins to evaluate the importance of fully developed flow

The success of chemically cleaning membranes depends on the cleaning cycle, type of cleaner, concentration, hydrodynamics, pressure and temperature. These are very important parameters and the majority of the flux is recovered if they are chosen correctly. The aim of this work was to clean membranes fouled under similar conditions using different hydrodynamics. Cleaning was either conducted in place or in a stirred beaker. When cleaning was conducted in place the importance of entry designs, fully developed flow, sudden expansion, and gradual contraction were compared to the dynamics in a stirred cell. It was found that when the flow was fully developed cleaning was significantly better. High cleaning efficiency could also be reached if the flow was not fully developed so long as there was a sudden expansion between the inlet pipe and the module. Further more, cleaning in place was found to be 20-35% more efficient than cleaning in a beaker. Even when the membrane cleaned in the beaker was also physically cleaned (wiping the surface) the recovered flux was still 20% less than that obtained for membranes cleaned in place.