Skip to main content

IFAS Process for Nitrogen Removal with an HRT of 4 Hours

Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial


This paper presents the experimental results obtained in an Integrated Fixed Film – Activated Sludge (IFAS) Bardenpho pilot plant (320 litres) operated at a Hydraulic Retention Time (HRT) of 4 hours and the comparison with HRT of 9 hours. The aerobic fraction was about 57% and divided into two main reactors (N1 and N2) which were filled with AnoxKaldnes K3 carriers (500 m2/m3). In addition, the plant was capable of providing methanol dosaging to the second anoxic reactor for the purposes of denitrification.

Batch tests of the nitrate production rate (NPR) and the endogenous carbonaceous oxygen uptake rate (OUR) were carried out in order to quantify the activity and the concentrations of nitrifying (XA) and heterotrophic (XH) bacteria in each location (the suspension and biofilms of the N1 and N2 aerobic reactors). The calculated concentrations of XH and XA were analysed on the basis of equations developed in a conceptual approach in which the bacteria concentrations are expressed as a function of the substrate removal rates, the solids retention times (SRT) and the lysis.

The operation at an HRT of 9 hours and high temperature revealed that the concentration of nitrifiers in suspension was high, but in the case of the N2 reactor was low in the biofilm. This occurred because the aerobic SRT turned out to be higher than the inverse of the nitrifier growth rate. However, at an HRT of 4 hours and T = 16°C, nitrifier concentrations in all the locations (in the suspension and biofilms of the N1 and N2 reactors) were high, resulting in very high nitrification rates (393 gN/m3aer·d) for the whole process. Concerning denitrification, reasonable effluent nitrate concentrations were achieved so as to meet the requirement of total nitrogen below 10 mgN/L.

Keywords: Batch tests; hydraulic retention time (HRT); integrated fixed film – activated sludge (IFAS) process; nitrogen removal

Document Type: Research Article


Publication date: January 1, 2010

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 These proceedings are not peer reviewed.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access.
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • ingentaconnect is not responsible for the content or availability of external websites

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
ingentaconnect 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