City of San Jose’s Journey to Mechanical Biosolids Dewatering

Presentation Description: One of the largest water resource recovery facilities in California, the City of San José - Santa Clara Regional Wastewater Facility’s (RWF) is completing their journey to modernize their current approach to biosolids dewatering. The RWF is replacing the current 750-acre lagoon stabilization and solar drying beds with a compact and efficient Digested Sludge Dewatering Facility (DSDF) sized to process 254,000 lbs/day of digested sludge with provisions for future expandability to 320,000 lbs/day. The current process utilizes significant acreage, is a long process, and requires use of heavy equipment to excavate and load dewatered biosolids. The new DSDF modernizes the approach to dewatering through the use of centrifuge dewatering, with elevated live bottom dewatered cake storage/truck loading for an efficient, space saving modern approach to dewatering and cake hauling.

The DSDF project was executed as a progressive design build (PDB) with construction and startup of the facility completed in Fall 2025. The DB team of Walsh/Black & Veatch developed new ways to interact to gain consensus and ensure the City’s input to the design was received and implemented appropriately with the design being completed during the COVID-19 pandemic. The use of interactive tools, 3D models, and detailed presentations were pivotal to the success of the program. Concurrent to the design of the new DSDF, the City was completing a project to transition the anaerobic digestion process from mesophilic to a Temperature Phased Anaerobic Digestion (TPAD) process. This transition posed additional challenges on the dewatering team as the new facility needed to ensure adequate dewaterability for the new digestion process before the process was operational. The DB team developed processes and infrastructure, and validation steps to provide the City with a robust and reliable process while addressing the uncertainties of a changing biosolids treatment process. The presentation will: 1) present the unique attributes of the new facilities; 2) highlight operation-centric design approaches and current operation; 3) identify innovative cost saving approaches; and 4) showcase project stages from early design through final construction; 5) proving the system through testing and start-up activities.