Discharge standard of pollutants for urban sewage treatment plants is a regulation implemented by the State Environmental Protection Administration on July 1 2003. The scope of application of Pollutant Discharge Standard for Urban Sewage Treatment Plants is clearly defined as the national professional pollutant discharge standard specially formulated for the discharge of sewage, waste gas and sludge from urban sewage treatment plants, which is applicable to the discharge and control management of sewage, waste gas and sludge disposal in urban sewage treatment plants.