Enabling lagoons to remove cold water ammonia with less space and cost
Tuesday, September 29, 2026 12:45 PM to 2:15 PM · 1 hr. 30 min. (US/Central)
New Orleans Convention Center
Technology Spotlight
Hall H Booth 7249
Information
Recent advancements in submerged attached-growth reactor (SAGR) technology are making lagoon wastewater treatment a more accessible option for small and rural wastewater systems looking to meet tomorrow's nutrient treatment requirements.
As regulatory pressures tighten and infrastructure constraints persist, small communities require compact, reliable, and cost-effective solutions. The SAGR system, developed and implemented at over 150 installations, directly addresses these needs by enabling post-lagoon nitrification under cold-water conditions while maintaining a low operational burden and reduced footprint.
The technology consists of a fully aerated reactor bed utilizing clean stone media to support biofilm growth, enabling ammonia oxidation even in temperatures below 0.5°C. In addition to ammonia removal, the system provides polishing for biochemical oxygen demand (BOD), total suspended solids (TSS), and enables opportunities for total nitrogen (TN) reduction through recycle configurations. These characteristics make SAGR particularly well-suited for small lagoon-based systems seeking upgrades without full process replacement.
The primary objective of the study was to evaluate whether SAGR systems could be reduced in size and cost while maintaining treatment performance, thereby improving accessibility for small and rural communities. Methodologies included pilot-scale and full-scale testing in Manitoba, Canada under cold weather conditions, focusing on increased hydraulic and ammonia loading rates as well as alternative aggregate gradations in the media bed. Loading rates up to five times historical design standards were evaluated, alongside comparative testing of multiple aggregate sizes to determine impacts on treatment efficiency, system capacity and cost.
Findings demonstrate that SAGR systems can be downsized by 35–65% without compromising nitrification performance or effluent quality, even under winter operating conditions. Broadened aggregate specifications further reduce capital costs by increasing material availability and enabling beneficial use of quarry byproducts, while maintaining ammonia removal, as well as BOD and TSS polishing. These results highlight key design considerations, including loading thresholds, media gradation, and site-specific constraints such as footprint and hydraulics.
The system operates with relatively low automation and operator attention compared to conventional mechanical plants, making it appropriate for small communities with limited staffing resources. Its passive biological process and simple aeration requirements reduce operational complexity while ensuring consistent compliance.
This work provides a learning opportunity by presenting the scientific basis of cold-temperature nitrification, the influence of media characteristics on biofilm performance, and practical insights into scaling treatment technologies for small systems. It also introduces a proven supplier and solution pathway for rural communities facing emerging ammonia regulations, reinforcing the role of innovative yet accessible infrastructure in sustainable water management.
As regulatory pressures tighten and infrastructure constraints persist, small communities require compact, reliable, and cost-effective solutions. The SAGR system, developed and implemented at over 150 installations, directly addresses these needs by enabling post-lagoon nitrification under cold-water conditions while maintaining a low operational burden and reduced footprint.
The technology consists of a fully aerated reactor bed utilizing clean stone media to support biofilm growth, enabling ammonia oxidation even in temperatures below 0.5°C. In addition to ammonia removal, the system provides polishing for biochemical oxygen demand (BOD), total suspended solids (TSS), and enables opportunities for total nitrogen (TN) reduction through recycle configurations. These characteristics make SAGR particularly well-suited for small lagoon-based systems seeking upgrades without full process replacement.
The primary objective of the study was to evaluate whether SAGR systems could be reduced in size and cost while maintaining treatment performance, thereby improving accessibility for small and rural communities. Methodologies included pilot-scale and full-scale testing in Manitoba, Canada under cold weather conditions, focusing on increased hydraulic and ammonia loading rates as well as alternative aggregate gradations in the media bed. Loading rates up to five times historical design standards were evaluated, alongside comparative testing of multiple aggregate sizes to determine impacts on treatment efficiency, system capacity and cost.
Findings demonstrate that SAGR systems can be downsized by 35–65% without compromising nitrification performance or effluent quality, even under winter operating conditions. Broadened aggregate specifications further reduce capital costs by increasing material availability and enabling beneficial use of quarry byproducts, while maintaining ammonia removal, as well as BOD and TSS polishing. These results highlight key design considerations, including loading thresholds, media gradation, and site-specific constraints such as footprint and hydraulics.
The system operates with relatively low automation and operator attention compared to conventional mechanical plants, making it appropriate for small communities with limited staffing resources. Its passive biological process and simple aeration requirements reduce operational complexity while ensuring consistent compliance.
This work provides a learning opportunity by presenting the scientific basis of cold-temperature nitrification, the influence of media characteristics on biofilm performance, and practical insights into scaling treatment technologies for small systems. It also introduces a proven supplier and solution pathway for rural communities facing emerging ammonia regulations, reinforcing the role of innovative yet accessible infrastructure in sustainable water management.