Membrane performance with a pulp mill effluent: Relative contributions of fouling mechanisms

Abstract

Severe flux decline was observed during ultrafiltration of a pulp mill effluent. Membrane fouling was the result of varying combinations of adsorption, pore plugging and concentration polarization or gel layer formation. A wide range of membrane materials and pore sizes were evaluated, showing the relationship between the membrane material, pore size and the relative contribution of the different fouling mechanisms. Individual resistances were evaluated for adsorption, Ra, pore plugging, Rpp, and concentration polarization, Rcp, using a series resistance model. These were based on the pure water flux for (1) the new membrane, Ji, (2) after static adsorption with the mill effluent, Ja, (3) the product rate when ultrafiltering the effluent, Jr, and (4) the pure water permeability with the fouled membrane, ,If. These resistances were shown to be misleading in terms of the observed flux loss for cases with significant adsorptive fouling. Adsorptive fouling was underestimated and concentration polarization overestimated. An alternative method, which we shall call flux loss ratios, is proposed, which is based on the flux decline due to a particular mechanisms as a fraction of the overall flux decline. These new measures more accurately reflect the flux decline attributable to each fouling mechanism.

Resistance in series model for ultrafiltration of mosambi (Citrus sinensis (L.) Osbeck) juice in a stirred continuous mode

“…Here also, the fouling resistance is the major contributor and with increase in Reynolds number the contribution of pore plugging resistance decreases substantially. Similar results are reported for pulp mill effluent [19].…”

Adsorptive fouling of inorganic membranes during microfiltration of vegetable oils

“…The adsorption of molecules under static conditions (membrane soaked in the solution to be filtered) can in-troduce an additional resistance and hence lower the initial flux [33]. For the investigated oils the intensity of this effect seems to be highly dependent on all interacting species (composition of the polar lipids and surface properties of the membrane).…”

Natural organic matter removal and flux decline with charged ultrafiltration and nanofiltration membranes

“…A resistance-in-series model was used to quantify the relative contributions of the membrane (R m ), adsorptive fouling (R a ), pore plugging (R pp ) and concentration polarization (R cp ) [19] …”