Skip to main content

Disinfection 2005 Manuscript Presentation Number: 1 ALT B: Evaluation of Submerged Induction Mixers to Improve Coliform Disinfection by Chlorine at the Sacramento Regional Wastewater Treatment Plant

Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial

Abstract:

The Sacramento Regional Wastewater Treatment Plant (SRWTP) began implementation of a submerged induction mixers (SIMs) pilot study in late 2003 to evaluate mixing and disinfection efficiencies. A relatively high chlorine dosage had been found necessary to achieve effluent requirements for total coliform from a pure oxygen activated sludge treatment process using the current turbine pump, chlorine injectors, and flash mixers (flash mixer system, or FMS). Preliminary economic analyses indicated that there was a possibility of chemicals cost savings of chlorine and sulfur dioxide and electric energy that would recover the SIM costs in less than a year.

The pilot study included installation of six SIMs — four 20 horsepower units and two 25 horsepower units in two channels at the effluent observation structure (EOS channels). One 25-hp SIM, and two 20-hp SIMs were installed in each EOS channel, directed against flow, with an average wetted cross-sectional area of 96 ft2 (8 ft by 12 ft) and an average velocity of 1.2 to 1.8 ft/sec. Water quality and other operational data were collected prior to and post installation of the SIMs and would be used to compare with the current FMS that had a relatively low energy coefficient “G”.

Initial chlorine capacity tests indicated that chemical feed capacity of each SIM was far less than projected by the manufacturer. Additional observations included inadequate mixing, decrease of pH, and higher chlorine dosages. To address these issues, the SIM manufacturer recommended replacing the smaller vacuum enhancer with larger ones to increase chemical feed capacity and to place additional units in each EOS channel to provide better mixing. Additional tests of the SIMs with large vacuum enhancer rings, the placement of six SIM units in one EOS channel were run, and results were found to be similar to previous tests. In addition, there was no improvement of disinfection efficiency as compared with the flash mixers system even though chlorine dosage almost doubled. The SIM pilot study was therefore terminated.

It is apparent from these results that the hydraulic mixing regimes of the SIM in channel configurations, similar to SRWTP, are not well known, and care must be exercised in applications for large channels.

Document Type: Research Article

DOI: https://doi.org/10.2175/193864705783978168

Publication date: 2005-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more