Biological Wastewater Treatment

Biological Wastewater

Utilizing naturally occuring bacteria and micro-organisms to breakdown organic contaminants in wastewater

Biological wastewater treatment is a very effective and common treatment step in many industrial and municipal wastewater facilities.

Harnessing the power of bacterial and other micro-organisms, biological wastewater treatment is an economic way to breakdown organic contaminants from a wide variety of wastewater streams.

Biological Wastewater Treatment Technologies are a critical component in many wastewater treatment systems. These systems are an effective tool to breakdown organic material and other pollutants to help organizations meet discharge permit requirements and reduce sewer surcharges.

Anaerobic Wastewater Treatment


Anaerobic wastewater treatment processes use bacteria to breakdown BOD (Biological Oxygen Demand), COD (Chemical Oxygen Demand), and other organic contaminants with the absence of oxygen. Anaerobic systems do not require the addition of air to the reactors, which lowers energy costs to operate the system. In many instances, anaerobic digestion systems can be energy positive. Anaerobic systems are also able to treat wastewater that has higher concentrations of BOD/COD.

During the anaerobic digestion process, the bacteria create biogas as a by-product that can be harvested and utilized in an electrical generator or boiler. Anaerobic digestion also generally produces lower amounts of sludge, when compared to aerobic systems.

Common Anaerobic Systems:

  • High Rate - Granular Anaerobic Digestion (UASB - Upflow Anaerobic Sludge Bed & EGSB - Expanded Granular Sludge Bed)
  • Medium Rate - Anaerobic MBR (Membrane Bio Reactors)
  • Low Rate - CSTR (Continuously Stirred Tank Reactor)

Aerobic Wastewater Treatment


Aerobic wastewater treatment systems include the addition of air (oxygen) within the wastewater reactor. These systems are effective in reducing BOD/COD to very low levels. In many, cases aerobic systems are used in conjunction with anaerobic systems to polish wastewater streams to remove nutrients or polish prior to discharge. These systems are also very resilient to variations in temperature and can effectively be used in almost any climate. Also, these systems can be installed in series or combined together to increase treatment capacity.

Common Aerobic Systems


Learn more and register for one or more of our upcoming Tech Talks!
Featured Videos
Connect with global technology water & wastewater experts from Veolia as they share insights and creative ways our technologies generate value, reduce risk, and improve operations.


Featured Resources & Information

Removing nutrients can help organizations meet their discharge limits and protect the environment.
Case Studies
Browse our extensive library of case studies featuring a variety of technologies
Browse our extensive library of on-demand technical webinar resources
Browse our large selection of technologies related to water and wastewater technologies