Abstract:The design scale of reconstruction and extension project of a wastewater treatment plant (WWTP) in Nantong is from 48 000 m3/d to 96 000 m3/d. The design effluent quality is upgraded to B standard in Discharge Standard of Pollutants for Urban Wastewater Treatment Plants (DB 32/4440—2022). The main difficulties to be faced are the high requirements for effluent quality parameters, solidification of the existing structure frame for civil engineering, and the construction process not able to affect the normal operation of the WWTP. Therefore, the main technology is considered to use the modified Bardenpho process and to extend the treatment capacity of secondary treatment facilities in order to achieve the purpose of replacing the old with the new. In addition, through in-depth research on the current facilities, the flexible cut-over construction processes are used to ensure the minimum influence on the operation of the WWTP during the reconstruction and extension. The main technology of reconstruction and extension is the pre-treatment + modified Bardenpho biological reaction tank + radial flow secondary sedimentation tank + high-efficiency sedimentation tank + cloth filter + ultraviolet combined with chlorine disinfection. According to the current facilities complying the new effluent standard, the technological idea is determined, which can be referred for the similar projects.
