Final answer:
Methane (CH4) is the product of anoxic sewage treatment used to heat and power water treatment facilities by combustion.
Step-by-step explanation:
The product of anoxic sewage treatment that can be used to heat and power an entire water treatment facility is methane (CH4). During the process of anaerobic decomposition or fermentation, organic waste such as municipal sewage and garbage is broken down by anaerobic bacteria, resulting in the production of methane. This methane is a relatively clean fuel that burns efficiently and can be captured to generate electricity or supply heat. Thus, methane is the component that can be combusted to provide energy for heating and power generation, which aligns with option D, 'both rely on the generation and combustion of methane', in the reference material provided.
The product of anoxic sewage treatment that can be used to heat and power an entire water treatment facility is methane (CH4). Methane is generated through the anaerobic decomposition of organic waste, such as municipal sewage and garbage, livestock manure, and kitchen and garden scraps. It can be captured and burned to produce heat or electricity, making it a renewable and efficient energy source.