Biosolids Digester Facilities Plant

MWH, in conjunction with Webcor (joint venture partner), broke ground on the $1.78 billion Southeast Water Pollution Control Plant (SEP) Biosolids Digester Facilities Project (BDFP) in San Francisco in June 2019.
The San Francisco Public Utilities Commission (SFPUC) is the third largest municipal utility in California, and the SEP is the SFPUC’s largest wastewater treatment facility, treating 80% of San Francisco’s sewage and stormwater flows. An average of 60 million gallons daily (MGD) of dry weather flow moves through the SEP, reaching up to 250 MGD during rainstorms.

As part of the SFPUC’s Sewer System Improvement Program, a 20-year, multi-billion-dollar citywide investment to upgrade aging sewer systems, the BDFP will replace existing digester facilities with expanded relocated facilities, and will maximize control of odors, reduce energy consumption, reuse of biogas and present a Class A biosolids, through the thermal hydrolysis process. The new infrastructure will eventually replace almost 50% of the plant’s processes.

The BDFP is one of the first projects in the US to use the Cambi Thermal Hydrolysis Process (THP). This technology will enable the new facilities to produce higher-quality Class A biosolids, capture and treat odors more effectively, and maximize biogas utilization. Having installed THP processes for an array of clients in the UK and the US, MWH has valuable and unique expertise in these innovative systems.