Skip to main content

Cost Savings and Performance Improvement of Large System Iron Salt Use for Integrated Sulfide Control and Chemically Enhanced Primary Treatment by Using Peroxide Regenerated Iron Technology

Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial

Abstract:

San Diego's Point Loma WWTP is a 160 MGD (240 MGD permitted), 100% advanced primary treatment plant that has historically used iron salts for collection system sulfide control and chemically enhanced primary treatment. Beginning in 2006, a PRI-SC® (Peroxide Regenerated Iron – Sulfide Control) program was implemented by adding H2O2 at the intermediate pump station PS2 (in place of the FeCl3), and again to the plant influent (ahead of FeCl3 addition for CEPT). The application of PRI-SC® in the Point Loma system was designed to provide at least 685/day in cost savings, to be achieved through reduced ferric chloride use at PS2 and Point Loma, while improving sulfide control and CEPT performance. Since integrating the PRI-SC® program full-time in 2008, SDMWD is realizing savings of approximately 4,700 per day (∼1.72 million/yr) compared to the 2007 baseline iron salts program. At the same time, both sulfide control and CEPT performance has improved. The cost savings were helped by the hedging aspect of the PRI-SC® program – iron salt price volatility in 2008 and 2009 was upwards of 45%. The PRI program has reduced the total iron salt use from the 2007 baseline rate of 32.5 dry tons per day to approximately 19.3 dry tons per day in 2009, with the core savings coming from an overall reduction in ferric chloride use at PS2 and the treatment plant (Table 1). Significantly, ferric chloride use at PS2 was eliminated and, for CEPT, reduced from 24 mg/L to 10 mg/L (16.6 to 6.8 dry tons per day) with no loss in performance. In addition, total sulfide removal has improved over baseline levels, and average CEPT performance exceeds the permit levels at 89% for TSS and 65% for BOD, and effluent water quality has improved (with 60% less spent iron (as FeS) present in the ocean discharge). For the most part, digester biogas H2S levels were maintained below the permit requirement of < 40 ppm, but required approximately twice the baseline FeCl2 feed rate. Even so, the overall program has maintained the stated savings benefit.

Keywords: Chemically Enhanced Primary Treatment (CEPT); PRI-SC; Peroxide Regenerated Iron; Sulfide control; hydrogen peroxide; iron salts

Document Type: Research Article

DOI: https://doi.org/10.2175/193864710798158517

Publication date: 2010-01-01

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