Launch Slideshow

Continuously sequencing reactor

Down to a science

Down to a science

  • Continuously sequencing reactor

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    Continuously sequencing reactor

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    Source: Schreiber LLC

    The CSR process cycles through the aerobic, anoxic, and anaerobic phases in a single basin.

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    Photo: Clayton County Water Authority

    The Shoal Creek water reclamation plant in Clayton County, Ga., uses a continuously sequencing reactor for denitrification.

  • Continuously sequencing reactor

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    Continuously sequencing reactor

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    The CSR process cycles through the aerobic, anoxic, and anaerobic phases in a single basin.

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Implications for the Future

Some areas of the country have adopted goals for TN limits. Goals are not permit limits. However, the plants operating in areas in which goals have been established are directed to voluntarily strive to meet these goals. Although a plant may have a current TN permit of 10 mg/L, operators will work to meet a much more stringent target or goal.

TN limits of 3 to 4 mg/Lalready have been established as a goal in California, Florida, and the Chesapeake Bay area. Such goals often serve as precursors to future permit limits. Once it has been proven that a particular goal is achievable, it eventually will be established as an actual regulated limit for future permits.

Consequently, as wastewater treatment professionals, we should anticipate that our future TN permit limits will be set somewhere in the 3 to 4 mg/L range. CCWA, already having a rich history of TN removal, is prepared for such TN requirements.

One of the most intriguing aspects evolving from this historical review is that the relatively inexpensive solution of upgrading a control system should not be overlooked in our rush to meet new requirements. Often by simply installing a more advanced concept control system in existing facilities, we can meet the challenge of tighter requirements—without making huge investments in additional structures.

— Foreman is consulting engineer with The Resource Group, Hoover, Ala.; Beroset is the engineer of record for the Shoal Creek WRF and is currently with HDR, Austin, Texas.

The following individuals also contributed to this article:

Curtis Price, superintendent, Shoal Creek WRF; Bruce Wilson, superintendent, Northeast WRF; Jim Poff, manager of water reclamation, CCWA; Mike Buffing-ton, program manager of planning and construction, CCWA; John Shepherd, vice president of technology, Schreiber LLC, engineer of record for the Northeast WRF.