Skip to main content


Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

Achieving phosphate removal to very low levels recently refocused the attention of the wastewater engineering profession on the design principles and various mechanisms that can produce effluent phosphate concentrations below 10 μgP/L (with TP being usually less than 100 μgP/L or 0.10 mgP/L). Current equilibrium models used for design (WEF, 1998) are based on dissociation and solubility principles and cannot account for variable precipitate stoichiometries and time dynamics. DCWASA initiated a research project to investigate the potential chemical, physico-chemical and physical mechanisms and their consequence on engineering design and operation of these systems. For iron mediated phosphate removal the iron is added to the wastewater stream in concentrated/acidic form. The alkalinity of the wastewater stream neutralizes the acidic ferric solution and results in rapid precipitation of hydrous ferric oxides (HFO). Simultaneous with HFO precipitation is soluble phosphate removal by co-precipitation and by adsorption of phosphate onto existing HFO particles. Chemically, co-precipitation and chemisorption can be viewed as the same process; phosphorus in phosphate and iron in HFO share one or more oxygen atoms. Important but frequently ignored factors for design of chemical phosphorus removal systems include sorbent to sorbate (Fe/P) ratio, G-value (mean velocity gradient) and reaction time (system SRT). The reaction time is important for both slower diffusion reactions that enhance P removal, and aging of metal flocs that reduce active surface sites and reduce the HFO sorbent capability for P removal. Experimental methods, results and the equilibrium part of the model is presented.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Document Type: Research Article

Publication date: 2007-01-01

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 These proceedings are not peer reviewed.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
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