What is the purpose of a vacuum/pressure relief valve on an anaerobic digester?

The primary purpose of a vacuum/pressure relief valve on an anaerobic digester is to maintain safe operating pressures within the system. Anaerobic digesters produce biogas, primarily composed of methane and carbon dioxide, during the degradation of organic matter. As gas is generated, the pressure inside the digester can build up. If this pressure exceeds the design limits, it can lead to structural damage or potential failure of the digester. Conversely, if the pressure becomes too low, it can create a vacuum that might disrupt the process and affect the integrity of the digester.

The vacuum/pressure relief valve acts as a safety device that opens at predetermined pressure levels, allowing excess gas to escape if pressure is too high, or allowing air in to prevent a vacuum condition if pressure drops too low. This ensures that the digester operates within safe pressure parameters, protecting both the equipment and the environment.

In contrast, other options do not accurately represent the function of this valve. For instance, preventing methane gas from reaching the heat exchanger or preventing CO2 from being released to the atmosphere are not functions associated with the relief valve. Additionally, while increasing digester capacity can be a consequence of efficient gas management, it is not the primary purpose of the relief valve