Dissolved oxygen (DO) is defined in biological treatment as the relative measure of oxygen dissolved in wastewater available to sustain life, including living bacteria. The concentration of dissolved oxygen (DO) in the aeration tank(s) of an activated sludge system is one of the most important process control parameters.


Indicators of low dissolved-oxygen conditions include:

  • substantial presence of low dissolved-oxygen filamentous bacteria in the activated sludge,
  • turbid effluent,
  • Dark gray or black-colored mixed liquor (often with a putrid odor).
Typical DO Level required at all water Tanks >2.0mg/L
Comfort DO level with minimal dead zones >=5.0mg/L




  1. Use of Chemical INPUTS

OXY-SUPER: Provides sufficient dissolved oxygen; Adjust the pH; Reduces the subaqueous content of ammonium and nitrogen; Eliminates carbon dioxide and sulfureted hydrogen; Prevent anaerobe from proliferation and killing nosogenetic bacteria , Typical Dose: 5 grams/ KL/ week

  1. Increasing blower efficiency
  • Dirty Air Filters :Replace or clean air filters
  • Check for Inlet Air Flow restrictions : Can be caused by a closed valve
  • Operate atleast 2 blowers on 24X 7 basis
  1. Diffuser Cleaning:Diffusers are subject to fouling and deterioration and need to be cleaned on a regular basis
  1. Aeration in grease traps : Aerating the grease trap creates a mini-waste water treatment plant environment. Aeration increases oxygen and ubiquitous aerobic bacterial populations, and softens and greatly reduces the grease cap, thus completely eliminating odor and clarifying the water. 
  1. AIRBLOWER INPUT BARSCREEN CHAMBER/ COLLECTION TANK: Aerating the bar screen chamber will start Oxygen diffusion from this tank and will help increase DO levels and control odors.
  1. INCREASING H.R.T. in AERATION TANK: At times when BOD Load is high increasing the Hydraulic retention time of wastewater in the FAB tank will increase DO Levels and Stop nitrification bubbles in the clarifier. 
  1. Visual Inspection of Aeration Tanks :Good airflow not only ensures good dissolved-oxygen concentration, but also good mixing. Reactors should be checked periodically to ensure that all portions of the reactor are being adequately mixed and that there are no dead spots that can produce anaerobic conditions. A procedure to do this is to take mixed-liquor grab samples at different locations and depths in the biological reactors and check for consistent suspended solids levels.

We hope you will find these steps useful and easy to incorporate in your plant, for any further details  or queries, we remain to serve you.

write to us at  for a speedy solution to your wastewater trouble.


Published by superweldcasestudies

This is a blog for uploading case studies of Superweld clients

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