A new parameter for membrane cleaning evaluation

Cleaning is an important step in membrane processes, such as microfiltration, ultrafiltration, nanofiltration and reverse osmosis; since the efficiencies of these latter are related to cost of labor, energy, chemicals and water use; cleaning can have a large effect on process productivity. Nowadays, today two kinds of parameters are used for cleaning efficiency evaluation. One compares only fluxes and the other only resistances between new and used membrane after the cleaning process. The aim of this paper is to review and compare those parameters and propose a new one, involving flux recovery and resistance recovery, which one was called: membrane performance recovery. This one was defined as the ratio between the average membrane flux after cleaning and the original membrane flux. Three different situations for determination of flux recovery, resistance recovery and membrane performance recovery were considered in this research. In the first and second ones, ceramic membranes fouled with goat and cow milk, respectively, were cleaned using Ultrasil ^®11. In the third one, a polymeric membrane fouled with beetroot juice was cleaned using Ultrasil^®10. The chosen situations showed the convenience of using this new parameter.