Graduation Year

2006

Document Type

Thesis

Degree

M.S.E.V.

Degree Granting Department

Civil and Environmental Engineering

Major Professor

Robert P. Carnahan, Ph.D.

Co-Major Professor

Marilyn Barger, Ph.D.

Committee Member

Daniel H. Yeh, Ph.D.

Keywords

lime softening, membrane water treatment, carbonated soft drinks, alkalinity reduction, immersed membrane

Abstract

Lime softening, chlorination, clarification and filtration have been long recognized

treatment processes for beverage water specifically the carbonated soft drink (CSD) because

it provides consistent water quality required for bottling plants, however these processes are

becoming uneconomical and causes more problems than the benefits they offer. These

processes require very large foot print, occupy large plant volume, and generate large

volume of sludge which causes disposal problems. Chlorination produces trihalomethanes

(THMs) and other by-products which are detrimental to health and imparts tastes to the final

products. Using the newly developed submerged spiral wound ultrafiltration membranes in

conjunction with lime softening may replace the conventional lime softening, clarification

and filtration processes.

This research was conducted to demonstrate the feasibility of integrating immersed

ultrafiltration (UF) membrane with lime softening. The objectives of this research was to

achieve the water quality required by the CSD bottlers; determine the relationships of

operating parameters such as pH and membrane flux with trans-membrane pressure (TMP),

and membrane permeability; determine the optimum dosage of lime; evaluate the operating

parameters as basis for the design and construction of the full scale plant; and predict the

membrane cleaning intervals.

A pilot unit consisting of lime reactor and UF system was designed and built for this

research. The pilot unit was operated at various pH ranging from 7.3 to 11.2 and at

membrane flux rates of 15, 30 and 45 gfd. The pilot unit was also operated at the CSD

bottler’s operating conditions which is pH 9.8 at flux of 30 gfd. The pilot unit operated for a

total of 1800 hours. The raw water source was from city water supply.

The filtrate from the pilot unit achieved alkalinity reduction to 20 to 30 mg/L

preferred by CSD bottlers, with lime dosage close to the calculated value. The filtrate

turbidity during the test was consistently within 0.4 to 0.5 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 research can use as the basis of

designing and operating a full scale Lime Softening UF Treatment Plant.

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