At Petaluma wastewater plant, the future is now

It is said you can learn a lot about a person by looking at their garbage. Turns out, you can learn just as much about the character of Petaluma by looking at its sewage - or, thankfully, at the facility that processes it.

During its 10 years, the Ellis Wastewater Treatment Facility has reshaped itself to take in waste produced by a rapidly changing city, factoring in an increased population and new industries like large-scale beer production.

Recently-completed projects costing roughly $9 million have changed the face of the wastewater facility by expanding treatment capacity, tackling hard-to-process industry waste and building a system that will provide biofuel to city vehicles.

“We’ve been under construction pretty much since 2014, which was five years after the plant opened,” said Deputy Director Leah Godsey Walker. “So, we’ve been building for quite a bit.”

The first project, installed in 2014, tackled the facility’s primary enemy: baby wipes. Screens were placed at the headworks facility to help catch a profusion of wipes that residents improperly flush down their toilets. Walker said these create significant blockages and create serious issues for the plant.

Although these wipes cause headaches and indignation among employees, it’s not the only type of solid waste that the facility has invested in dealing with.

“We had a plant designed for what we thought (we needed),” said Public Works Director Dan St. John during a Dec. 4 event celebrating the plant’s decennial. “Then comes Petaluma Poultry, then comes Lagunitas, then comes our other industry partners.”

Construction of the high-strength waste receiving station will soon give the plant the ability to process by-products from food and production facilities, such as Lagunitas and Petaluma Poultry, that can’t go down the drain. These include animal processing waste, fats, oils and liquids used to process food and beverages.

“One of the driving issues we had was the solids waste process,” Walker said. “We have a lot more food and beverage industries than anticipated during the facility design.”

As a result, Walker said they added a second digester in 2017 and equipment that extracts water from solid waste, added mid-2019.

In the digester, sometimes compared to a human stomach, microorganisms break down organic waste and produce methane gas. Walker said the second digester gave the facility the increased capacity it needed to go forward on its biomass to biofuel project, or B2B, which turns methane gas into fuel.

The final construction element scrubs, conditions and condenses the methane gas and transforms it into a biologically derived natural gas. The compressed natural gas station has been the most lengthy project of the five, and cost roughly $1.26 million more than the expected $3 million. Of the $9 million total in improvements, $3 million was provided through a grant from the California Energy Commission.

Both the high strength waste station and the methane gas compressor are fully constructed, but waiting on final permitting and approval before they start operations.

Walker said the goal is to be able to apply all methane production toward fueling plant operations and city vehicles, and is hopeful the first trucks powered by Petaluma’s waste will hit the roads in the next month.

(Contact Kathryn Palmer at On Twitter @KathrynPlmr.)

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