West County Wastewater (WCW) and OPTERRA Energy Services have reported progress on WCW’s Clean & Green project, which upgrades wastewater treatment infrastructure and expands energy generation and resource recovery at the district’s Water Quality and Resource Recovery Plant in California.

The project includes new digesters, rotary drum thickeners, sludge dewatering equipment and a thermal dryer designed to enable production of U.S. EPA Class A biosolids. Additional improvements include an equalization basin, upgraded headworks, solar installations, a cogeneration system and a microgrid for backup power.

The upgrades are expected to generate nearly $83 million in savings over the project’s life, reduce greenhouse gas emissions by more than 90% and cut annual biosolids disposal costs by nearly $2 million. Producing Class A biosolids could also support reuse as fertilizer and reduce reliance on chemical fertilizers.

Construction began in 2022, with the first phase covering treatment infrastructure, energy systems and resource recovery. The project also replaces open-air sludge drying lagoons, creating opportunities for Bay Trail improvements, wetland restoration and a potential living levee to protect infrastructure from rising sea levels, according to WCW General Manager Andrew Clough.