A membrane bioreactor (MBR) is a wastewater treatment process where a perm-selective membrane is integrated with a biological process – a suspended growth bioreactor.
A membrane bioreactor is essentially a version of the conventional activated sludge (CAS) system. Whereas the CAS process uses a secondary clarifier or settlement tank for solid/liquid separation, an MBR uses a membrane. This provides a number of advantages relating to process control and product water quality.
There is no significant difference in the design of the MBR technology for a process treating industrial rather than municipal wastewater. The key differences between the two applications are that, for industrial effluents, there are:
A full needs analysis is required before selecting a membrane bioreactor system, first of all to confirm that an MBR will be the most cost effective solution for a particular requirement, taking everything into account. Secondly, to ensure an MBR is the most appropriate choice of technology for the circumstances.
Operation and maintenance (O&M) parameters for an MBR include:
The arguments surrounding the precise target sludge (or mixed liquor suspended solids, MLSS) concentration to use when running an MBR are pretty well developed but what is it that ultimately sets the solids concentration range?