California utility selects thermal hydrolysis systems for biosolids digesters

San Francisco

San Francisco Public Utilities (SFPUC) has selected three Cambi thermal hydrolysis technology systems for new biosolids digester facilities. The technology will allow the SFPUC to enhance odour control, boost energy recovery, and reduce the plant’s environmental footprint.

The SFPUC is investing over $3 billion to upgrade and modernize the Southeast Treatment Plant, the City’s largest wastewater treatment facility, as part of a more extensive citywide Sewer System Improvement Program.

The Biosolids Digester Facilities Project is an essential component of the larger Southeast Treatment Plant upgrade, which will replace and relocate the existing, outdated solids treatment facilities with more reliable, efficient, and modern technologies and facilities. The new digesters will use a state-of-the-art sludge treatment line using Cambi’s thermal hydrolysis systems.

“We are making generational investments at the Southeast Treatment Plant, our largest wastewater treatment facility,” said Dennis Herrera, General Manager of the SFPUC. “We took great care in designing it to be a modern and efficient resource-recovery centre, improving operations and the well-being of employees and nearby residents. We are pleased to see the project taking another major step toward completion with this contract for thermal hydrolysis technology. This is about doing what’s right for our communities, the environment, and our ratepayers.”

The contract is a win-win for both Cambi and the SFPUC. It is a major contract in the United States for Cambi, and the use of thermal hydrolysis technology will allow the SFPUC to produce higher quality “Class A” biosolids. The nutrient-rich wastewater byproduct, known as ‘biosolids’, are used as a high-quality fertilizer. The higher classification will expand the byproduct’s beneficial uses.

In addition, the Cambi technology allows the SFPUC to enhance odour control and boost biogas output and energy recovery. Once operational, the new facilities will reduce the carbon and environmental footprint associated with biosolids management.

“We are honored to have a role in assisting the SFPUC in achieving their ambitious sustainability goals.”, said Eirik Fadnes, Cambi CEO.

He added: “Thermal hydrolysis was selected as a core technology for the project in 2016 to provide greater security as biosolids regulations become increasingly stringent and restrictive. We look forward to getting started on this important delivery for the metropolitan area of San Francisco”,

The project is carried out by a joint venture of MWH Constructors and Webcor Builders. Cambi has worked with MWH on several thermal hydrolysis projects in the US and other countries.

The project is Cambi’s tenth in the US but the first on the West Coast. The current project timeline plans the delivery of the thermal hydrolysis systems in 2027 and commissioning in 2028.

The large-scale investments to the Southeast Treatment Plant will reduce odours – improving the quality of life for nearby residents and employees –, improve earthquake resiliency, prepare for sea level rise, and ensure operational redundancy and efficiency. Once the upgrades are finished, the upgraded facility will look better, smell better, and work better for the community, SFPUC staff and all of San Francisco.