ANALYSIS ON DESIGN CHARACTERISTICS OF A LARGE-SCALE SEMI-UNDERGROUND WASTEWATER TREATMENT PLANT

The Futian Sewage Treatment Plant (STP) is the first semi-underground STP in China,with a design capacity of 4×10⁵ m³/d, and the covering land as the second floor was planned to build as a municipal park. This STP effluent complied with the first A standard of Discharge Standard of Pollutants for Urban Sewage Treatment Plants (GB 18918-2002). The moisture content of sludge cake was reduced to 50%. This paper introduced the wastewater treatment process selection, design features, and application of innovating technologies. Due to the higher concentration influent SS, heavy nitrogen removal, and high requirements of sludge treatment, the treatment processes included rectangular primary sedimentation tank for the pretreatment process, multi-influent, multi-stage enhanced denitrification and improved A²/O biological tank, rectangular secondary sedimentation tank, fiber rotary filter and ultraviolet disinfection. The sludge treatment process finally employed the combination of mechanical concentration + plate and frame deep dehydration. After the project completed, the production operation was stable, and the water quality of effluent was better than the design standard.