VACOMASS®  Biocontrol

  • Software for the control of intermittent aeration for nitrification/denitrification: process transitions can be recognized based on the response of simple process parameters such as DO, pH and Redox (ORP)
  • Software to manage the actual aerated volume of tanks or zones
  • Prevents over- and under-aeration
  • Reduces energy costs and improves process stability
VACOMASS® Biocontrol Software to control load-depending DO-level (based on actual NH4+-N), internal recirculation rate (based on NO3—N)

VACOMASS®  Biocontrol

Plants require individual aeration control concepts based on plant capacity, plant design and permit requirements. The level of capital investment and the potential for energy cost reduction also play a significant role.

The combination of VACOMASS® system components allows you to implement individual concepts for aeration control, as well as intermittent aeration. It begins with simple installations to ensure equal air distribution, continues to the implementation of conventional dissolved oxygen control, and carries through to complex installations with control loops for individual, local airflow control, load-based header pressure control during nitrification and scheduling of nitrification and denitrification phases based on process parameters such as pH and Redox (ORP).  

VACOMASS® biocontrol is an optional module in the VACOMASS® flexcontrol cabinet.

VACOMASS® biocontrol controls the nitrification and denitrification of an intermittently aerated wastewater treatment plant. Based on process parameters such as pH, Redox (ORP), ammonium and/or nitrate concentration in the secondary treatment tank, the system recognizes when nitrification is complete and shuts off the aeration. The timely switch-over prevents over-aeration and reduces energy costs.

This also provides additional time for improved denitrification, reducing the total Nitrogen in the plant effluent.
In plants with pre-anoxic zones for denitrification, depending on actual loading or the ammonium concentration at the end of the secondary treatment, the plant can:

  • adjust the DO set points based on the loading and
  • switch the aeration to swing zones on and off.


This improves nitrification performance in winter months, when the wastewater temperatures are lower and the biological activity is down. During summer or during extended low-load periods, such as weekends, denitrification is improved due to the greater anoxic volume. The control of the DO set points prevents, or at least reduces, DO being recycled from over-aerated nitrification zones to the anoxic zone where it would inhibit denitrification.

The internal nitrate recycle rate can be controlled based on the nitrate concentration in the effluent. This not only saves pumping energy during low-load periods, it also improves denitrification because of the higher residence time.