Enhancement of methane production in mesophilic anaerobic digestion of secondary sewage sludge by advanced thermal hydrolysis pretreatment

Water Res. 2015 Mar 15:71:330-40. doi: 10.1016/j.watres.2014.12.027. Epub 2014 Dec 24.


Studies on the development and evolution of anaerobic digestion (AD) pretreatments are nowadays becoming widespread, due to the outstanding benefits that these processes could entail in the management of sewage sludge. Production of sewage sludge in wastewater treatment plants (WWTPs) is becoming an extremely important environmental issue. The work presented in this paper is a continuation of our previous studies with the aim of understanding and developing the advanced thermal hydrolysis (ATH) process. ATH is a novel AD pretreatment based on a thermal hydrolysis (TH) process plus hydrogen peroxide (H2O2) addition that takes advantage of a peroxidation/direct steam injection synergistic effect. The main goal of the present research was to compare the performance of TH and ATH, conducted at a wide range of operating conditions, as pretreatments of mesophilic AD with an emphasis on methane production enhancement as a key parameter and its connection with the sludge solubilization. Results showed that both TH and ATH patently improved methane production in subsequent mesophilic BMP (biochemical methane potential) tests in comparison with BMP control tests (raw secondary sewage sludge). Besides other interesting results and discussions, a promising result was obtained since ATH, operated at temperature (115 °C), pretreatment time (5 min) and pressure (1 bar) considerably below those typically used in TH (170 °C, 30 min, 8 bar), managed to enhance the methane production in subsequent mesophilic BMP tests [biodegradability factor (fB) = cumulative CH4production/cumulative CH4production (Control) = 1.51 ± 0.01] to quite similar levels than conventional TH pretreatment [fB = 1.52 ± 0.03].

Keywords: Advanced thermal hydrolysis; Biochemical methane potential tests; Mesophilic anaerobic digestion; Methane production; Secondary sewage sludge; Thermal hydrolysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaerobiosis
  • Biodegradation, Environmental
  • Bioreactors
  • Hydrogen Peroxide / chemistry
  • Hydrolysis
  • Methane / chemistry*
  • Sewage / chemistry*
  • Temperature
  • Waste Disposal, Fluid / methods*
  • Water Purification / methods


  • Sewage
  • Hydrogen Peroxide
  • Methane