This Old Ditch: Oxidation Ditch Improvements for Increased Capacity and Reliability

Last Modified: Jan 31, 2019

Authors:

  • David Wankmuller, Joe Rohrbacher, Jared Hartwig, Olivia Flynn - Hazen and Sawyer

This presentation will detail the drivers and recommended optimization improvements for two different oxidation ditch projects. Both facilities implement oxidation ditches for carbon and nutrient removal and are looking to increase capacity, flexibility, and reliability of their biological process. Process evaluations were performed for both facilities and different solutions were selected based on the clients overall goals.

Facility A has a current rated capacity of 18 mgd and utilizes two oxidation ditches for carbon and ammonia removal. Oxygen is supplied via mechanical surface aerators and a supplement fine bubble diffused aeration system. A process evaluation was performed focusing on the aeration requirements to provide a capacity of 22.5 mgd within the existing oxidation ditches. The recommended improvements for the oxidation ditches to increase capacity from 18 to 22.5 mgd include, but are not limited to:

  • Keep the existing oxidation ditch flow configuration
  • Remove the existing brush rotors and ceramic diffusers and install membrane diffusers
  • Remove existing aeration system blowers and provide new blowers
  • Provide a total of four new submersible mixers per basin to achieve required basin velocity gradient
  • Facility B has a current rated capacity of 6.0 mgd and utilizes four oxidation ditches for carbon and nutrient removal. Oxygen is supplied via mechanical surface aerators. A process evaluation was performed focusing on the process improvements necessary to provide a capacity of 9.0 mgd within the existing oxidation ditches. The recommended improvements for the oxidation ditches to increase capacity from 6.0 to 9.0 mgd include, but are not limited to:

  • Modify the oxidation ditches to a plug flow configuration to increase capacity to 9.0 mgd
  • Remove the mechanical surface aerators and provide membrane diffusers
  • Provide new blowers
  • Provide control valves and instrumentation for integrated automated control of the modified aeration basins
  • This presentation will detail the drivers and recommended optimization improvements for two different oxidation ditch projects.

    For more information, please contact the author at dwankmuller@hazenandsawyer.com.

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