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.
This calculator also appears on ActivatedSludge.com, our consulting site. Results are for training and operator use; always follow your plant’s procedures.