Talking Climate · The Wilkes Center for Climate Science and Policy

35: Wastewater Treatment Could be a Solution for Cleaner, More Efficient Fertilizer

·30 min·1 clip

Nitrous oxide is 270 times more potent than CO2, yet it's barely discussed in climate conversations.

The problem starts with wastewater, which is not glamorous but does a lot of damage when nutrients get loose. Chambliss opens by tying human waste to harmful algal blooms and nitrous oxide, described here as much more potent than CO2. Then the episode turns to fertilizer. Ammonia still depends on the pre-World War I Haber-Bosch process, an energy hungry route responsible for about 2% of global CO2 emissions. Roca Water is looking at the overlap. Lumley talks about wastewater less as something to throw away and more as a messy stream full of nutrients, dissolved minerals, and critical metals. Her route into the work came through water itself. She says people tend to stay in the sector for decades because it touches daily life and still has plenty left to solve. Electrochemistry is the tool she lands on. After her PhD, Lumley looked at environmental uses like desalination and critical metal recovery before narrowing in on nutrients. The fit is fairly direct. Wastewater utilities need to cut nutrient loads, while the U.S. needs a lot of fertilizer and has reason to care about lower energy domestic production. The conversation stays practical, which helps. Pilot testing is the next hurdle. Lumley says Roca plans to test wastewater samples in a controlled setting, share results with potential partners, and then build a real world pilot system, likely at a wastewater treatment plant in the Bay Area. Roca is also likely to fundraise in spring of next year to move from bench scale testing into that first pilot. If it works, the payoff is clean and useful: less nutrient pollution, plus recovered fertilizer ingredients that could replace some carbon intensive ammonia production.

As heard by us

Wastewater, fertilizer, and climate math, framed through one startup's pilot-stage wager.

Talking Climate keeps its focus on Margaret Lumley of Roca Water as she makes a tidy case that wastewater can address water pollution and the carbon cost of fertilizer together.

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Why you'd press play

For when you want wastewater climate tech that links nutrient recovery to fertilizer.

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