Case Study: A Municipal WWTP Reduced TN from 25mg/L to 12mg/L with Sodium Acetate

A municipal WWTP in North China had low influent carbon-nitrogen ratio; effluent TN stayed at 20~25mg/L for a long time, failing to meet the stable ≤15mg/L (Class 1A) requirement.

After bench tests determined the sodium acetate dosage, a sodium acetate dosing point was added in the anoxic zone, adjusted by feedback from influent TN and online nitrate. After two months of commissioning, effluent TN stabilized at 10~12mg/L, denitrification rate improved markedly, and system shock resistance increased.

This is a typical industry scenario overview; it shows that carbon source selection, dosing point and metering control are equally important. Specific values should follow actual bench tests.