Skip to main content

Estimation of Autotrophic Maximum Specific Growth Rate Constant—Experience from the Long-Term Operation of a Laboratory-Scale Sequencing Batch Reactor System

Buy Article:

$30.00 plus tax (Refund Policy)


The autotrophic maximum specific growth rate constant, μ A,max, is the critical parameter for design and performance of nitrifying activated sludge systems. In literature reviews (i.e., Henze et al., 1987; Metcalf and Eddy, 1991), a wide range of μ A,max values have been reported (0.25 to 3.0 days −1); however, recent data from several wastewater treatment plants across North America revealed that the estimated μ A,max values remained in the narrow range 0.85 to 1.05 days −1. In this study, long-term operation of a laboratory-scale sequencing batch reactor system was investigated for estimating this coefficient according to the low food-to-microorganism ratio bioassay and simulation methods, as recommended in the Water Environment Research Foundation (Alexandria, Virginia) report ( Melcer et al., 2003). The estimated μ A,max values using steady-state model calculations for four operating periods ranged from 0.83 to 0.99 day −1. The International Water Association (London, United Kingdom) Activated Sludge Model No. 1 (ASM1) dynamic model simulations revealed that a single value of μ A,max (1.2 days −1) could be used, despite variations in the measured specific nitrification rates. However, the average μ A,max was gradually decreasing during the activated sludge chlorination tests, until it reached the value of 0.48 day −1 at the dose of 5 mg chlorine/(g mixed liquor suspended solids · d). Significant discrepancies between the predicted X A/ Y A ratios were observed. In some cases, the ASM1 predictions were approximately two times higher than the steady-state model predictions. This implies that estimating this ratio from a complex activated sludge model and using it in simple steady-state model calculations should be accepted with great caution and requires further investigation.

Keywords: Activated Sludge Model No. 1; bioassay; modeling; nitrification; sequencing batch reactor

Document Type: Research Article


Publication date: April 1, 2008

More about this publication?
  • Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year.

    Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
  • Editorial Board
  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Membership Information
  • Information for Advertisers
  • WEF Bookstore
  • 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