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Updated: Jul 18, 2026

Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors
07:59

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Published on: December 6, 2018

Ozonation reduces sludge production and improves denitrification.

Magdalena A Dytczak1, Kathleen L Londry, Hansruedi Siegrist

  • 1Department of Civil Engineering, University of Manitoba, Winnipeg, Canada MB R3T 5V6.

Water Research
|December 26, 2006
PubMed
Summary

Partial ozonation of return activated sludge improves wastewater denitrification by up to 60%. This sludge treatment also minimizes waste solids and enhances soluble chemical oxygen demand (COD) through cell lysis, with less impact on nitrification in alternating reactors.

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Published on: September 11, 2016

Area of Science:

  • Environmental Engineering
  • Water Treatment Technologies
  • Wastewater Treatment

Background:

  • Activated sludge is a key component of biological wastewater treatment.
  • Sludge minimization and enhanced denitrification are critical challenges in wastewater management.
  • Ozonation is a potential pre-treatment method for activated sludge.

Purpose of the Study:

  • To investigate the effectiveness of partial ozonation of return activated sludge.
  • To assess the impact of ozonation on denitrification and waste sludge minimization.
  • To compare the effects of ozonation under aerobic and alternating anoxic/aerobic conditions.

Main Methods:

  • Nitrifying sequencing batch reactors were operated under aerobic and alternating anoxic/aerobic conditions.
  • One reactor in each set served as a control, while the other received partial ozonation of return activated sludge.
  • Ozone dose was varied to determine its effect on sludge properties and treatment performance.

Main Results:

  • Ozonation significantly decreased the amount of solids produced, with higher sludge reduction in alternating anoxic/aerobic reactors (up to 25%) compared to aerobic reactors (10%).
  • Denitrification rates improved by up to 60% due to increased soluble chemical oxygen demand (COD) from cell lysis caused by ozonation.
  • Nitrification rates were negatively impacted, particularly in the aerobic reactor, likely due to direct damage to nitrifying organisms and increased competition from heterotrophs.

Conclusions:

  • Partial ozonation of return activated sludge is effective in enhancing denitrification and minimizing waste sludge production.
  • Alternating anoxic/aerobic conditions mitigate the negative impacts of ozonation on nitrification compared to purely aerobic conditions.
  • Ozonation offers a promising approach for improving wastewater treatment efficiency by addressing sludge minimization and denitrification simultaneously.