Microsoft has signed a carbon removal agreement with Crew Carbon for up to 23,602 carbon removal units generated from Crew’s wastewater alkalinity enhancement (WAE) technology.

Crew’s proprietary process works by dosing alkaline minerals, such as calcium carbonate, into wastewater treatment plants in order to reduce the carbon footprint of the plants' operations. Wastewater treatment plants produce CO2 as a byproduct, which is usually released into the atmosphere. Crew claims that through its WAE technology, it can convert dissolved CO2 into stable bicarbonate ions instead of letting it escape as gas. The inert bicarbonate is subsequently discharged into oceans, rivers, or aquifers.

Instead of building new infrastructure, the company integrates the process within existing wastewater treatment plants, claiming it can take a plant from initial assessment to full deployment in about three months.

“Microsoft’s offtake agreement with Crew supports the advancement of a novel, wastewater-based approach that is highly durable and measurable,” said Phillip Goodman, carbon removal portfolio director at Microsoft. “Crew has shown that carbon removal in the wastewater sector is implementable and scalable with high Monitoring, Reporting and Verification (MRV) certainty.”

According to Crew, its closed-system approach includes inlet and outlet monitoring, and all of its carbon removals are quantified via plant-level monitoring, tracked with downstream modeling, and verified by independent registries.

“This agreement with Microsoft is a major milestone for Crew, and further validates our approach to delivering high-quality, durable carbon credits while we optimize wastewater treatment performance,” said Dr. Joachim Katchinoff, CEO and co-founder of Crew.

Crew was spun out of Yale University by Dr. Joachim Katchinoff and Professor Noah Planavsky. Its first commercial project is located at the East Shore Water Pollution Abatement Facility in New Haven, Connecticut. The plant processes 40 million gallons (151.4 million liters) of wastewater a day and is set to become one of the largest carbon removal projects on the US East Coast.

Its deal with Microsoft is not its first with a data center firm. In May of last year, it signed a $32.1 million offtake agreement with carbon buying consortium Frontier for 71,878 tons of carbon dioxide removal, to be delivered between 2025 and 2030.

Microsoft has signed numerous carbon removal deals over recent years; however, it has significantly reduced its purchasing cadence in 2026, following reports earlier this year that it was adjusting the pace of its carbon removal purchases.

Since then, it has signed two other carbon removal deals, including a 650,000-ton deal with Danish bioenergy carbon capture and storage firm BioCirc, and a 36,920-ton deal with enhanced rock weathering firm Alt Carbon in Darjeeling, India.