Abstract:The design scale of a wastewater treatment plant (WWTP) upgrading and expansion project in Shenzhen is expanded from 60 000 m3/d to 160 000 m3/d. The designed effluent quality is upgraded from the Class I B standard in the Discharge Standard of Pollutants from Municipal Wastewater Treatment Plant (GB18918-2002) to Quasi IV class water standard in Environmental Quality Standards for Surface Water (GB3838-2002). The actual land area of this project is only 4.2 hm2. Through the demolition of the original structures, a set of sewage treatment facilities with a design scale of 160,000 m3/d is newly built. The technological process of multi-stage AO biological reaction tank + double-layer secondary sedimentation tank + magnetic coagulation sedimentation tank + UV disinfection is adopted in the upgrading and expansion project. The total investment of this project is 521.65 million rmb, and the operating cost is 1.13 rmb/m3. The main part of this project was completed and opened to water in 2019. The effluent water quality can stably reach the Quasi-IV water standard.