In order to ensure a homogeneous and stable effluent quality is fed to the biological treatment process, a mixed balance tank with 24-hour residence time is generally required.
This prevents cleaning processes in the mill (utilizing high temperature, variable pH wash water) from upsetting the anaerobic digester, which is sensitive to pH change.
Externally mounted mixing pumps recirculate the fluid in the tank, providing the necessary mixing to create a homogeneous solution ready for treatment.
The tank can be of constructed from concrete, steel panels or can be a covered pond.
Some methane gas may be generated in this tank due to initial anaerobic decomposition, so the tank may need to be connected to the biogas storage.
