Techno-economic impact of air sparging prior to purification of alkaline extracted wheat bran hemicelluloses by membrane filtration

Air sparging of alkaline-extracted wheat bran hemicelluloses prior to ultrafiltration has been shown to increase the flux. The techno-economic impact of air sparging on the cost of concentration and purification of wheat bran hemicelluloses by ultrafiltration and diafiltration was studied in this work. Two alkaline hemicellulose solutions were purified until the conductivity of the diafiltration permeate was < 1 mS/cm. Both solutions were pretreated by the removal of suspended matter using dead-end filtration with diatomaceous earth as filter aid. One of the solutions was further pretreated by air sparging for 4 h at 80 degrees C prior to concentration by ultrafiltration. Air sparging increased the average flux during ultrafiltration from 52 L/m(2)h to 151 L/m(2)h, and during diafiltration from 46 L/m(2)h to 130 L/m(2)h. A higher diafiltration factor was needed for the air-sparged solution, requiring a higher amount of diafiltration water. However, the cost of purifying the hemicelluloses was reduced from 1375 (sic)/ton hemicelluloses to 1122 (sic)/ton by sparging the solution with air prior to membrane filtration.