Final answer:
CH4 (methane) is the product of anoxic sewage treatment that can be used to heat and power an entire water treatment facility.
Step-by-step explanation:
The product of anoxic sewage treatment that can be used to heat and power an entire water treatment facility is CH4 (methane).
Methane is produced during the anaerobic decomposition of organic waste, such as municipal sewage, garbage, and livestock manure. It can be captured and burned to generate heat or electricity. Methane is a clean fuel that burns efficiently and is considered carbon neutral.