Odor and Corrosion Mitigation Strategies for a Complex Large Diameter Interceptor System

摘要

North Texas Municipal Water District (NTMWD) owns and operates the Upper East Fork Interceptor System (UEFIS), a large collection system serving 12 customer cities in North Central Texas and comprised of 216 miles of 8- to 72-inch gravity sewer, force mains and 19 lift stations. Wastewater from the UEFIS is treated by two regional wastewater treatment plants (RWWTP): Wilson Creek and Rowlett Creek RWWTP, both owned and operated by NTMWD. NTMWD currently implements a combination of vapor-phase and liquid-phase (ferrous salts, hydrogen peroxide, calcium hydroxide, magnesium hydroxide, and calcium nitrate) odor control in the UEFIS. NTMWD is experiencing rapid growth in infrastructure and community encroachment, which necessitated an odor control project with the following objectives: 1. Evaluate the effectiveness of cunent odor control practices 2. Develop additional odor and conosion control strategies to proactively address these emerging needs 3. Update NTMWD's current odor control master plan. To meet the project objectives, NTMWD contracted with Hazen and Sawyer (Hazen) for an odor control study. As part of the study, Hazen developed an odor control road map which included evaluation of the existing system, identification of system hot spots from odor and corrosion perspective, field sampling of odor parameters and development of a hydrogen sulfide model to predict current and future sulfide generation in the system. The field sampling and modeling results were used to develop and evaluate potential odor and corrosion control alternatives. In addition, development of cost-effective liquid and gas phase odor control recommendations, including optimization of current liquid phase treatment, to obtain target liquid and vapor hydrogen sulfide in the system from an odor and corrosion perspective were included.