Integrated Precipitative Softening and Immersed Spiral Wound Ultrafiltration Membrane Treatment of Beverage Water

摘要

Lime softening, chlorination, clarification and filtration have been long recognized treatment processes in beverage plants because it provides consistent water quality however, these processes require very large plant area, generate large volume of sludge which causes disposal problems and causes more problems than the benefits they offer. Chlorination produces trihalomethanes (THMs) and other by-products which are detrimental to health and imparts tastes to the final products. Using the submerged spiral wound ultrafiltration membranes when integrated with lime softening may replace the conventional lime softening, clarification and filtration processes.rnThis research was conducted to demonstrate the feasibility of integrating immersed ultrafiltration (UF) membrane with lime softening. A pilot unit consisting of lime reactor and UF system treating municipal water supply was operated for a period of 1800 hours, at various pH ranging from 7.3 to 11.2 and at membrane flux rates of 15, 3 0 and 45 gfd. The filtrate from the pilot unit achieved alkalinity reduction to 20 to 30 mg/L preferred by carbonated soft drinks bottlers, with lime dosage close to the calculated value. The filtrate turbidity during the test was consistently 0.05 NTU. The TMP values obtained during the test ranges from 0.1 to 2.5 psi, while the permeability values ranges from 18.19 to 29.6 gfd/psi. The increase in flux results to corresponding increase in TMP, and increase in operating pH, increases the rate of TMP. Permeability decreases with increasing operating pH. The TOC reduction ranges from 2.6 % to 15.8% with increasing operating pH. No scaling of the UF membranes was observed during the test. Thirty days UF membrane cleaning interval was predicted. The results from this study can use as the basis of designing and operating a full scale Integrated Lime Softening UF Treatment Plant.