CHEMICAL CLEANING OF A TUBULAR MINERAL MICROFILTRATION MEMBRANE FOULED WITH A WHEY PROTEIN CONCENTRATE SUSPENSION- CHARACTERISATION OF HYDRAULIC AND CHEMICAL CLEANLINESS

摘要

We have characterised the cleaning efficiency of a microfiltration membrane in terms of both chemical and hydraulic cleanliness and searched for existing relationships between the water flux recovery and the residual amount of proteins deposited on membrane surface after cleaning. Fouling-cleaning sequences were carried out at pilot scale on a 0.1 μm tubular ceramic microfiltration membrane. A 3.5 wt % whey protein concentrate suspension was selected as a model fouling suspension. Sodium hydroxide was selected as a simple alkaline cleaning agent. Hydraulic cleanliness was evaluated by : i) percentage flux recovery, ii) a useful cleaning criterion representing the ratio of the residual fouling resistance to the initial membrane resistance : (Rn-Rm)/Rm<0.05 . Chemical cleanliness was evaluated by means of the measurement of the amount of residual proteins per unit membrane surface area (in μg.cm~-2) via the desorption of proteins using an anionic surfactant (sodium dodecyl sulphate). Two filtration operating parameters defining the cleaning operation were investigated : crossflow velocity (v) and cleaning time (tc). Crossflow velocity (1