Recorded Webinar: Food Waste Co-Digestion in California

Technology and Innovation

Webinar Speaker Bios

Moderator: Greg Kester, Director of Renewable Resource Programs, California Association of Sanitation Agencies

Greg serves as both the technical and programmatic contact for CASA members and conduit for emerging issues on state and federal level on all biosolids, renewable energy, recycled water, and related issues. Prior to joining CASA, Greg served as the state biosolids coordinator for the Wisconsin Department of Natural Resources. He represented all states in the nation, by their election, to USEPA on all biosolids issues. He served on the National Academy of Sciences Committee which evaluated federal biosolids regulations and produced the 2002 report: Biosolids Applied to Land: Advancing Standards and Practices. Greg holds a BS in Civil and Environmental Engineering from the University of Wisconsin – Madison and is a registered PE in Wisconsin.

Speaker Panelist: Charlotte Ely

Charlotte Ely is a supervisor in the State Water Resources Control Board’s Climate and Conservation unit. From 2006 to 2016, she worked for the U.S. Environmental Protection Agency’s Sustainable Water Infrastructure program, providing technical and financial support to increase water and energy efficiency in water, wastewater, and stormwater infrastructure. She lives in Sacramento with her husband and two daughters.

Speaker Panelist: Rashi Gupta, Vice President / Project Manager, Carollo Engineers

As a vice president and project manager with Carollo Engineers, Rashi Gupta has specialized in delivering sustainable solutions for biosolids management and wastewater treatment throughout her 17-year career. She obtained her Bachelors of Science in Civil Engineering from the University of California, Davis, and her Master’s Degree from the University of Texas at Austin. Rashi now serves as Carollo’s Biosolids Technology Integration Lead, focusing on solids projects throughout the country. She is a licensed civil engineer in California, and a member of the WEF Residuals and Biosolids Committee, where she serves as the vice-chair of the Solids Separation Sub-Committee.

Speaker Panelist: Elizabeth Charbonnet, Lead Engineer, Carollo Engineers

Elizabeth Charbonnet is a Lead Environmental Engineer at Carollo Engineers. She joined Carollo in 2013 and since that time has focused on wastewater solids management. Her experience includes integrated master planning, innovative biosolids treatment technologies, cogeneration design, and grant applications. She holds a Master’s Degree in Environmental Engineering from U.C. Berkeley and a Bachelor of Science Degree in Environmental Engineering Science from MIT.

Speaker Panelist: Sarah Deslauriers, Vice President, Carollo Engineers

Sarah has been specializing in sustainability, resource recovery, climate change analyses, greenhouse gas emission management, biosolids management, and master planning throughout her 17 year career (15 years at Carollo). She is a Vice President and Project Manager at Carollo serving as their Climate Change and Resilience Lead, and serves as the program manager for the California Association of Sanitation Agency’s Climate Change Program and the Bay Area Biosolids Coalition. In addition, Sarah is the Chair of the Bioenergy Technology Subcommittee for the WEF Residuals and Biosolids Committee. Sarah received her bachelor’s and master’s degrees from the University of Michigan.

Download the Report and Related Materials

State Water Board Report Announcement

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new report issued today by the California Environmental Protection Agency shows that at least half of California’s landfill-bound food waste could be processed at the state’s wastewater treatment plants and serve as an innovative power source.


Waste can be “co-digested” at these facilities, which involves adding organic wastes including municipal food scraps and industrial food processing wastes such as chicken blood to a facility’s anaerobic digester.

Building on a survey of the nearly 225 wastewater treatment plants in California, the report finds that many have the existing anaerobic digestion capacity to accommodate diverted food waste. While maximizing the use of that excess capacity would require additional infrastructure investments, the report shows such investments would benefit California’s economy while advancing environmental goals.

“We release this report just as California is experiencing the very real impacts of climate change,” said Jared Blumenfeld, California’s Secretary for Environmental Protection. “As our environmental problems become more tangled, we have to start planning for cross-cutting solutions like this. Co-digestion can be a triple threat against climate change: it can reduce organic waste in landfills while cutting greenhouse gas emissions and helping to clean wastewater.”

The report estimates the statewide capital investments required to use the co-digestion capacity range between $900 million and $1.4 billion. The net benefits to the state could be up to $255 million each year. 

Maximizing co-digestion capacity could reduce statewide greenhouse gas emissions by as much as 2.4 million metric tons of CO2-equivalent per year. That’s more than half of the emissions from landfills that California committed to reducing by 2030.

“The report’s findings are very promising,” said State Water Board Chair E. Joaquin Esquivel. “It shows California’s wastewater treatment plants have the existing anaerobic digestion capacity to accommodate at least half of California’s landfilled food waste—likely more. We look forward to working with our industry partners to get more of these projects off the ground.”