AWWA MTC64556

The combination of lime softening, chlorination, clarification and filtrationhave long been used as a treatment process in beverage plantsbecause it provides consistent water quality. However, theseprocesses require a very large plant area, generate a large volume ofsludge that causes disposal problems, resulting in creating more problems thanthe benefits they offer. Chlorination produces trihalomethanes(THMs) and other byproducts which are detrimental to health andgives a taste to the final products. Using submerged spiralwound ultrafiltration membranes integrated with lime softeningmay replace the conventional lime softening, clarification andfiltration processes.This research was conducted to demonstrate the feasibility ofintegrating immersed ultrafiltration (UF) membrane with limesoftening. A pilot unit consisting of lime reactor and UF systemtreating municipal water supply was operated for a period of 1800hours, at various pH levels ranging from 7.3 to 11.2, and at membrane fluxrates of 15, 30 and 45 gfd. The filtrate from the pilot unitachieved alkalinity reduction to 20 to 30 mg/L preferred bycarbonated soft drinks bottlers, with lime dosage close to thecalculated value. The filtrate turbidity during the test wasconsistently 0.05 NTU. The TMP values obtained during the testranged from 0.1 to 2.5 psi, while the permeability values rangedfrom 18.19 to 29.6 gfd/psi. The increase in flux resulted in acorresponding increase in TMP, and the increase in operating pHincreases the rate of TMP. Permeability decreases with increasingoperating pH. The total organic carbon (TOC) reduction ranges from 2.6 % to 15.8% withincreasing operating pH. No scaling of the UF membranes was observedduring the test. A thirty day UF membrane cleaning interval waspredicted. The results from this study can be used as the basis ofdesigning and operating a full scale Integrated Lime Softening UFTreatment Plant. Includes 12 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

03/01/2007

Number of Pages:

20

File Size:

1 file , 470 KB