Which solids treatment method produces methane gas used in other plant processes?

The treatment method that produces methane gas for use in other plant processes is anaerobic digestion. In anaerobic digestion, organic materials are broken down by microorganisms in the absence of oxygen. This process generates biogas, which primarily consists of methane and carbon dioxide. The methane produced can be captured and utilized as a renewable energy source, for heating, electricity generation, or as a fuel for vehicles, making anaerobic digestion an effective method for both waste management and energy recovery.

In contrast, composting is an aerobic process that decomposes organic waste with the help of oxygen, resulting in rich compost but not methane. Aerobic digestion, similar to composting, also requires oxygen and therefore does not produce methane. Sand drying beds serve to dewater sludge but do not generate gas, as they rely on evaporation and do not involve microbial digestion processes that would produce methane.