Calculate plant ammonia load, including a return stream like centrate, and the oxygen needed to nitrify it.
Ammonia Loading
Formula
Ammonia load, lb/d = Q, MGD x NH3-N, mg/L x 8.34 Side stream, lb/d = Side flow, gpd / 1,000,000 x NH3-N x 8.34
Inputs used
- Influent flow (MGD)
- Influent ammonia-N (or TKN) (mg/L)
- Side-stream flow, such as centrate (optional) (gpd)
- Side-stream ammonia-N (optional) (mg/L)
Worked example (White River WRRF, fictional)
- Plant = 8.0 x 26 x 8.34 = 1,735 lb/d
- Centrate = 0.035 x 800 x 8.34 = 234 lb/d
- Increase = 234 / 1,735 x 100 = 13.5%
Tips
- Centrate from anaerobic digestion often carries 500 to 1,000 mg/L ammonia-N.
Results are estimates for operator use. Check units and inputs, and confirm decisions with plant data and procedures.