Ammonia is a naturally occurring compound found in wastewater, but when levels are too high, it becomes a major environmental and regulatory problem. Excess ammonia fuels algal blooms, depletes oxygen, harms aquatic life, and can lead to toxic conditions in receiving streams. Understanding how to remove ammonia from wastewater efficiently is essential for any treatment operator, engineer, or municipality managing nutrient limits.
Why ammonia matters
High ammonia levels in wastewater can:
- Trigger eutrophication in lakes, ponds and streams
- Eutrophication: excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen
- Deplete dissolved oxygen that fish and other aquatic organisms depend on, ultimately leading to stress, suffocation and death
- Increase odor issues and community complaints
- Lead to costly fines as new federal and state rules tighten nutrient limits
How to remove ammonia from wastewater
Ammonia removal typically occurs through biological processes called nitrification and denitrification, in which different bacteria convert ammonia into harmless nitrogen gas under controlled oxygen conditions.
Core steps operators use:
1. Nitrification (aerobic process)
Bacteria convert ammonia into nitrite, then to nitrate using oxygen.
- Performed in aeration basins
- Requires ample dissolved oxygen
- Best bacteria: Nitrosomonas and Nitrobacter
2. Denitrification (anoxic process)
Nitrate is converted into nitrogen gas without oxygen. In reduced-oxygen environments, distressed aerobic bacteria consume oxygen from nitrate, a process sometimes referred to as nitrogen stripping.
- Occurs in specialized anoxic zones
- Reduces total nitrogen and aids in ammonia control
- Produces nitrogen gas that vents harmlessly into the atmosphere
Proven strategies
To achieve consistent ammonia reduction, operators rely on:
Biological techniques
- Extended aeration to hold solids longer and grow ammonia-eating bacteria
- Controlled air diffuser banks to switch between aerobic and anoxic cycles
- Return activated sludge management to maintain biomass
- Seed sludge startup to jump-start plant biology
Operational best practices
- Maintain sludge age of 20–30 days
- Monitor flow variations (especially in college or seasonal populations)
- Avoid oxygen intrusion into anoxic zones
- Periodically run full aeration to prevent solids buildup
Chemical methods (when needed)
Although not required for every facility, chemical approaches exist:
- Breakpoint chlorination
- Ion exchange
- Zeolite filtration
These tools are effective but often costlier than biological systems.
Real-world example of ammonia reduction: University of Louisiana Lafayette case study
A powerful demonstration of how to remove ammonia from wastewater comes from the University of Lafayette Louisiana’s (UL) 80,000 gpd treatment plant operated by Charles Corkern. UL faced a major infrastructure challenge: aging sewer lines, rapid student-housing expansion, and no available capacity to send additional flow to the city system. They needed a compact, quiet, odor-free wastewater solution installed in the middle of campus, surrounded by apartments, a daycare, pedestrian paths, and live oaks protected by strict preservation rules.
To solve the problem, Gainey’s provided a tailor-made extended aeration return-activated sludge plant engineered to handle unusually high-strength influent wastewater.
Influent vs. Effluent Results
| Parameter | Raw Influent | Final Effluent |
|---|---|---|
| BOD | 296 mg/L | 3 mg/L |
| TSS | 372 mg/L | 4 mg/L |
| Ammonia | 57 mg/L | 0.4 mg/L |
| Total Nitrogen | ~100 mg/L | 11.6 mg/L |
| Total Phosphorus | 1.8 mg/L | 6.4 mg/L |
What makes this plant impressive
- UL went from zero nutrient loading to full capacity in four days
- The plant operates entirely on airlift systems; no mechanical pumps in the process stream
- Carefully controlled aerobic and anoxic zones allow nitrifying and denitrifying bacteria to work efficiently
- Despite extreme influent strength, the system reduced ammonia levels by over 99%, from 57 mg/L to 0.4 mg/L
- The treatment performance exceeded permit limits without chemical additives
This case proves that even neighborhood-scale systems, when designed and operated strategically, can achieve big-plant results. It’s a textbook example of how to remove ammonia from wastewater using biological treatment, proper air management, and smart hydraulic configuration.
Gainey’s designs, manufactures and installs precast concrete wastewater treatment plants with third-party engineering approval. Connect with our team to learn how we can help you reduce ammonia and safeguard your discharge stream. Contact us to get started.
