Millions of Chinese citizens are flooding into urban areas throughout the country، with 70 percent of the nation’s population expected to reside in cities by 2030. As cities face an influx of residents، they also face an influx of wastewater and sludge. Currently، 80 percent of sludge in China is improperly dumped-—an increasingly controversial environmental issue that has urban centers scrambling to decrease pollution by improving their wastewater treatment plants (WWTPs). As it grapples with these challenges، China could use an example to follow. New York City’s large size and innovative wastewater system make it one of the only municipalities in the United States that can serve as a useful case study for China’s growing cities. New York City’s five boroughs must manage and treat the wastewater and waste generated by its 8.6 million residents. The city’s households and businesses typically produce tons of waste، about one quarter of which is organic. Fortunately، this organic waste isn’t actually waste at all; it can be processed in ways that produce energy. Some of New York City’s advanced treatment plants use innovative methods to capture valuable by-products of organic waste، such as methane and digestate، which can then be reused or sold. In addition to the standardized multi-stage wastewater treatment process، all NYC wastewater treatment includes an advanced process called anaerobic digestion (AD). This process allows anaerobic bacteria to “eat away” the organics in sludge، generating methane biogas as they do so. This methane—a notorious greenhouse gas that causes 25 percent of man-made global warming-—can be captured in vessels called digesters، preventing it from entering the atmosphere. The captured methane can then be used as a source of energy in the form of heat، renewable natural gas or even vehicle biofuel. At wastewater treatment plants that don’t use AD technology to capture methane، the organic-rich sludge is sent to landfills، where methane biogas is released directly into the atmosphere. All 14 wastewater treatment plants in New York City capture methane. At Newtown Creek Wastewater Treatment Plant، the city’s largest treatment facility، methane is captured in giant digester “eggs.” Thanks to a partnership with National Grid، the captured methane will soon be productively used as renewable natural gas (RNG)، enough RNG to heat 5،200 homes and reduce greenhouse gas (GHG) emissions by 90،000 metric tons CO2 equivalent. To make even more clean energy from waste methane gas، WWTPs can co-digest food waste and sludge during the AD process. In 2013، then-Mayor Michael Bloomberg passed co-digestion and composting bills that led to an increase in organic food waste available for co-digestion at New York City’s WWTPs; Newtown Creek is leading the charge. The private company Waste Management is partnering with Newtown Creek in a pilot co-digestion project. Both partners reap benefits: Newtown Creek receives higher quality methane gas and Waste Management gets a low cost and eco-friendly alternative to disposing food waste into landfills.