Ultrafiltration of Acid Whey in a Spiral-Wound Unit: Effect of Operating Parameters on Membrane Fouling

Membrane fouling by acid (cottage cheese) whey could be minimized by appropriate pH adjustment and removal of insoluble particulates. Acidifying pasteurized whey to pH 2 or 3 followed by conventional centrifugal clarification (e.g. 5000g for 20–30 sec) significantly improved flux over that of unadjusted whey. Neutralizing whey to pH 7 was also just as effective provided resulting insoluble particles could be removed efficiently. Operating at 50°C was slightly more beneficial than 40° or 30°C. High flow rates were beneficial only if transmembrane pressure was below some critical value (about 50 psig or 350 kPa in this case). At pressures higher than this, high flow rates significantly increased fouling rates. After prolonged operating time, neither flow rate nor pressure appeared to have a significant effect, due perhaps to a change in the mode of fouling from surface deposition to pore adsorption.