- 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.