Membrane Bioreactor (MBR)
A membrane bioreactor combines biological activated-sludge treatment with membrane filtration (typically UF or MF), replacing secondary clarifiers and producing high-quality effluent suitable for reuse in a compact footprint.
How it works
In an MBR, micro- or ultrafiltration membranes retain biomass and suspended solids directly, decoupling solids separation from settling. This allows operation at high mixed-liquor suspended-solids concentrations, shrinking tank volumes and eliminating clarifier upsets from poor sludge settleability.
Membranes are most commonly submerged directly in the bioreactor (immersed MBR) as hollow-fibre or flat-sheet modules, with permeate drawn under slight vacuum and air scour controlling fouling.
Advantages and limits
MBRs deliver very low effluent turbidity and near-complete solids removal, a strong basis for reuse, in roughly half the footprint of conventional plants. The trade-offs are higher energy demand for aeration and membrane scour, membrane replacement costs, and sensitivity to fouling — the focus of continual module and operating-strategy improvement.
MBR technology scaled rapidly in Asia, where suppliers such as Beijing OriginWater and Kubota deployed it across large municipal reuse programs.
- [1]The MBR Book: Principles and Applications of Membrane Bioreactors for Water and Wastewater Treatment. Butterworth-Heinemann, 2010.
- [2]Membrane Bioreactors for Wastewater Treatment. IWA Publishing, 2019.