Capturing carbon from wastewater
Could this innovation help to combat global warming?
Wastewater treatment contributes 2% 2% of global man-made greenhouse gas emissions. These emissions are the result of both the microbial digestion of organic matter and the generation of energy to power the treatment process.
Now, US startup CREW Carbon is working with industrial and municipal wastewater operators to offset this climate impact by capturing and storing CO2 permanently – all while treating wastewater effectively.
The company introduces naturally occurring carbonate minerals such as limestone into wastewater that contains atmospheric CO2 as a by-product of the breakdown of biological waste. The CO2 reacts with the carbonate minerals and is converted into dissolved bicarbonate ions – a form of carbon that is extremely stable. Because this bicarbonate is chemically inactive, it can be released into water courses, where the CO2 is effectively ‘locked in’ for thousands of years.
The whole process is enhanced with a patented sensor system that measures the chemistry of the carbon-rich water entering and exiting the system in real time. This is combined with smart dosing hardware that integrates into existing infrastructure and introduces precise amounts of mineral to the process water to optimise carbon removal.
CREW Carbon is set to remove
of CO2 between 2025 and 2030
CREW’s measurement, reporting, and verification system can quantify CO2 removal with high precision, meaning the process can yield valuable carbon removal credits that treatment facilities can then trade for additional income.
The technology was developed through years of research at Yale University. Having delivered its first pilot in 2022, CREW Carbon has since gone on to deliver further deployments. In December 2024, it was revealed that the startup would receive $32.1 million from carbon removal buyers to remove 71,878 tonnes of CO2 between 2025 and 2030. The deal was facilitated by advanced market commitment platform Frontier, which was created by Stripe, Alphabet, Shopify, Meta, and McKinsey.
Did you know?
The idea of using wastewater treatment for CO2 removal has several key benefits over other proposed approaches. Existing wastewater treatment infrastructure already channels CO2 into a closed system, and the CO2 in wastewater treatment tanks is more concentrated than it is in the air. As a result, CREW Carbon’s solution is very efficient from a CAPEX perspective. Moreover, many treatment facilities currently use harsh and carbon-intensive alkaline chemicals, such as caustic soda or quicklime, to regulate pH levels. Because CREW’s carbonate minerals are also alkali, they provide a safer, more consistent, lower carbon, and lower cost option for alkalinity optimisation. To remove barriers to adoption for wastewater operators, CREW takes care of the CAPEX and OPEX associated with new and expanded systems, and it also handles the sourcing and verification of the input materials.
