Final answer:
It is true that dewatering an anaerobic digester can create a dangerous explosive condition due to the presence of methane gas.
Step-by-step explanation:
The statement is true. When an anaerobic digester is dewatered for maintenance, there is a risk of creating a dangerous explosive condition. This risk arises because an anaerobic digester contains a mixture of gases, predominantly methane (CH4), which is highly flammable. When the digester is dewatered for maintenance, the removal of the water can lead to a concentration of methane in the headspace above the sludge, or even in the internal spaces and nearby areas if not handled correctly. Without the water seal, methane can come into contact with oxygen in the air, creating an explosive atmosphere, especially if there are any sources of ignition nearby, like sparks from tools or equipment. Therefore, proper safety protocols, including gas monitoring and ventilation, must be followed to prevent any explosive incidents.