The city's investing $67 million to increase efficiency at the Hunts Point Wastewater Treatment Plant.
Crews are installing 16 new centrifuges, which are used in the final steps of treatment.
The new machines consume 60 percent less electricity, and process 25 percent more waste than older models.
The Department of Environmental Protection says this will save the city more than $1.7 million a year on average and cut down on greenhouse gas emissions.
The agency is funding the work, while the New York Power Authority is implementing the upgrades, which are expected to be completed in 2020.