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Mark Pamperin
Product Manager - Biological Processes

VLR® System for Biological Treatment, BNR and Stormflow

Provides simultaneous nitrification / denitrification in a smaller footprint
VLR® Systems utilize looped reactors in series that allows DO stratification. The tanks are similar to oxidation ditches that have been flipped on their sides. There is an upper and lower compartment, separated by a horizontal baffle. The process was adapted from Orbal® Multichannel Oxidation Ditch technology and uses the same surface mounted discs to provide mixing and deliver oxygen. Typically, two or more basins make up the system, with the first tank operating as an aerated anoxic reactor.



  • Simultaneous nitrification/denitrification
  • Typical flow rate 2 MGD – 10 MGD
  • Biological phosphorus removal
  • Stormwater treatment
  • Contact tank for The Captivator®​ System


  • Common wall construction
  • Small footprint
  • Dual aerator design – Two sources of oxygen delivery (disc aeration and coarse bubble aeration)
  • Lengthy aeration retention time
  • Coarse bubble air diffusers add flexibility
  • DO stratification
  • Handles excessive storm water treatment

 key benefits

  • Lower construction costs
  • Less land area required
  • Operating flexibility
  • Low power costs
  • Easy to meet peak oxygen demands
  • Process adaptability
  • Peak flows five times the design flow VLR® System for Biological Treatment, BNR and Stormflow