Removal of ammonia nitrogen from wastewater using modified activated sludge

The removal of medium-low N-NH4 on activated sludge modified by ferric hydroxide suspension (FH-MAS) in batch studies was conducted as a function of pH, concentration of modifier, contact time, and initial concentration. The kinetics study showed that the sorption behavior fit well the pseudo second-order equation. An adsorption isotherms study indicated that FHMAS had a higher adsorption capacity for N-NH4 than other adsorbents. The mechanism of removal of N-NH4 by FHMAS was coexistence of adsorption and cation exchange. Initial N-NH4 concentration being 116 mg/l in metallurgical wastewater was reduced to 11 mg/l after adsorption treatment.