Reduction of Trihalomethane Precursors in Caloosahatchee River Water Using Membrane Processes

Abstract

This study investigated the effectiveness of using a polyamide, thin-film-composite low pressure membrane to remove organic constituents of Caloosahatchee River water in order to reduce trihalomethane format ion potential (THMFP). The Olga Water Plant, near Fort Myers, Florida, was selected due to a highly colored, organic-rich raw water source, and a long-term documented history of excessive trihalomethane formation following conventional treatment. A bench scale ultrafiltration unit which held a single membrane was used to test six ultrafiltration and one low pressure reverse osmosis membranes. These membranes had varying molecular weight cutoffs and varying material compositions. The optimal membrane had a nominal molecular weight cut-off of 500, operated at pressures below 120 psi, and produced a permeate quality which met the THM maximum contaminant level of 0.10 mg/L under "clean" operating conditions. The optimum membrane was used in two test matrices in which pressure and percent recovery (based on raw water input) were varied from 60 to 120 psi and 50 to 80%, respectively. The objective of the matrices was to determine the operating conditions which concurrently maximized permeate flux and minimized THM precursors. Results of short-term test matrices using a "clean" membrane indicated that a high quality permeate could be produced at feed pressures of 105 to 120 psi and at low recovery ratios of 60 to 70%, based on raw water input. Following the short-term matrices, a 700-hour duration bench scale study using the optimum membrane was performed in order to determine feasibility, and identify operating constraints. Permeate flux and permeate quality during the extended study were generally lower than the short-term tests at the same applied pressure and recovery conditions. The decrease in flux and permeate quality is attributable to membrane scaling and/or biological fouling at the membrane surface.

Notes

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Graduation Date

1989

Semester

Summer

Advisor

Taylor, James S.

Degree

Master of Science (M.S.)

College

College of Engineering

Department

Civil Engineering and Environmental Sciences

Format

PDF

Pages

162 p.

Language

English

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Identifier

DP0026951

Subjects

Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic

Accessibility Status

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