On the wastewater side they talk a lot about making treatment plants energy self-sufficient (or in the more popular language, reaching net zero energy).
They can talk that way largely because the water flowing into the plants brings an abundant and never-ending energy source, in the form of organic matter that can be converted to methane (biogas), a fuel for electric generators and boilers. They can even add materials like fats, oils, grease (FOG) and food waste to existing digesters and create even more fuel.
Water plants lack that luxury. They’re energy intensive but don’t have any obvious energy sources besides their
