14.2.2 The activated sludge process n Out Air Sludge Principle design of an activated sludge reactor with an aerated compartment (left) and a sludge separator(right). CoHO,Ns+O2>CO2+H2O+NH3 +biomass WH3-→NO2→NO→N2 C H O N + O → CO + H O + NH + biomass     2 2 2 3 NH3 → NO2 → NO3 → N2 − − 14.2.2 The activated sludge process