Skip to main content


Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial


The purpose of this research was to evaluate the relative merits of mesophilic and thermophilic digestion of municipal sludge in terms of polymeric conversion efficiency, process kinetics, gas productivity, and effluent quality. High-rate digestion experiments were conducted with primaryactivated sludge mixtures at 35° and 55°C at HRTs of 15, 7, and 3 days. The thermophilic cultures were developed by raising the temperature of the mesophilic inoculum to 55°C in one step. The thermophilic runs exhibited higher gas production rate, and gas and methane yields at all HRTs and loading rates of 2.1 - 7.3 kg VS/m3-day. Thermophilic effluents had higher pHs (7.5), alkalinities, and ammonia-nitrogen and VFA concentrations than mesophilic effluents under all operating conditions. The thermophilic process effected higher lipid conversion but lower carbohydrate reduction than the mesophilic process at all HRTs. However, total volatile solids reductions under thermophilic temperature were higher than those under mesophilic conditions at all test HRTs. Thermophilic effluents had much higher concentrations of ammonianitrogen, acetate, propionate, isobutyrate, isovalerate, and caproate than mesophilic effluents. These compounds were responsible, in part, for the thermophilic effluent being more odoriferous than the mesophilic effluent. Thermophilic acetogens and methanogens had higher μmax (maximum specific growth rates) and Ks (half-velocity constants) than mesophilic acetogens and methanogens. The higher Ks values explain the occurrence of C3 and higher fatty acids in higher concentrations in thermophilic effluents. Except for the slightly more odor, thermophilic digestion was superior to mesophilic digestion in all respects.

Document Type: Research Article


Publication date: 2000-01-01

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 These proceedings are not peer reviewed.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