SAGR™ Cold Climate Nitrification

Manufacturer: Nexom

SAGR™ Cold Climate Nitrification

Nexom is the exclusive source for the SAGR, a simple, powerful tool for fully nitrifying lagoon effluent in any climate. The SAGR consists of a clean stone bed that is fully aerated. In a typical configuration, water flows through the substrate horizontally, and a layer of insulating wood chips, mulch or shredded tires at the surface prevents ice formation in the bed, allowing the system to treat wastewater that is near freezing (<0.5°C).

Why do you need a SAGR? Lagoons are incredibly powerful ecosystems that cost-effectively, naturally remove a host of wastewater’s most harmful components with a minimum of operations or maintenance requirements. But lagoons often struggle to remove ammonia in winter for four reasons:

  1. If a facultative (un-aerated) lagoon freezes over, access to atmospheric oxygen is cut off, which is needed by nitrifying bacteria.
  2. Nitrifying bacteria require a surface to grow on, something that is not plentiful in a lagoon.
  3. The heterotrophic bacteria that consume cBOD5 tend to dominate nitrifying bacteria, meaning cBOD5 needs to drop below 25mg/L before nitrification can begin in earnest. Cold temperatures slow the metabolism of the heterotrophs. More of the lagoon retention time is required for BOD removal, reducing the available HRT for nitrification.
  4. Both the reproduction rate and the metabolism of the nitrifiers themselves slow as the water temperature drops. The low reproduction rate means that new biomass does not form quickly enough to make up for the reduced consumption of ammonia that occurs due to the lower metabolism. 

Key advantages:

  • Reduces Total Ammonia to <1 mg/L year-round, even in <0.5°C water
  • Polishes cBOD to <5 mg/L, TSS to <10mg/L, and provides partial effluent disinfection
  • O&M requirements similar to an aerated lagoon


  • Nitrification in any climate
  • Post-lagoon polishing
  • Airport de-icing fluid treatment
  • Decentralized wastewater treatment
  • Water reuse applications


HESCOland 2018

Jan 14, 2018

Several new manufacturers join us for this years HESCOland at Joint Expo

WEFTEC Road Rally

Sep 25, 2017

Visit each of our participating manufacturers booth and win prizes! 

Nexom to present, “Beating Ammonia Limits,” at Lagoon Seminar

May 2, 2017

Hear Nexom present, “Beating Ammonia Limits,” at the Lagoon Seminar to discover how your lagoon-based facility could achieve non-detect ammonia levels and broad-spectrum nutrient removal. 

HESCOland at MWEA/AWWA Joint Expo

Jan 18, 2017

HESCO will host a multi-booth interactive experience we call HESCOland.  Find the right equipment to complete your 2017 plans!