When sludge is withdrawn from a sludge gas collector tank, what must be added to prevent the development of negative pressure?

The correct course of action when withdrawing sludge from a sludge gas collector tank is to prevent the development of negative pressure within the system. Negative pressure can lead to issues such as the risk of air infiltrating the tank, which could disrupt the anaerobic digestion processes and potentially lead to non-optimal conditions for the treatment of sewage.

To maintain proper operating conditions, it’s essential to ensure that the pressure within the tank remains balanced. This is often achieved by either adding a certain volume of liquid or gas to create positive pressure or through careful management of the sludge withdrawal process to avoid creating a vacuum. However, the notion of adding negative pressure does not relate to traditional practices in sludge management, as this would exacerbate the problems associated with vacuum conditions.

Therefore, the answer revolves around maintaining a healthy environment in the sludge gas collector tank by carefully managing pressure to avoid complications that arise from negative pressure situations.