MBR - Membrane BioReactors for Wastewater Treatment

MBR - Membrane Bioreactor Systems are no longer viewed as a novel process as it is used more and more in wastewater treatment applications all over the world.

Wastewater represents a water resource and its reuse can significantly reduce the demand for water supply. Membrane Bioreactor is an effective and economic treatment process for water reuse and reclamation. Advanced membrane technology development includes membrane bioreactors and multibarrier reclamation processes using dual membrane stages. A common water reclamation process is by integrating MBR and RO (Reverse Osmosis) to produce high quality product water for reuse.

Compared with conventional activated sludge system, the membrane bioreactor system is much simpler, as shown below.

We supply a range of MBR Systems and modules to satisfy our customers' needs. By membrane configurations they can be classified as:

•  Hollow Fibre MBR
• Evoqua Memcor mbr module
• Zennon ZeeWeed mbr module
• Mitsubishi Rayon membrane module
• Citic Memstar mbr module
•  Plate and Frame MBR (Flat Sheet Membranes)
• Kubota mbr
• Hitachi membrane module - obselete and needs to use other compatible replacement modules e.g. WTA UNISOL MYTEX Modules
• Toray mbr module
• WTA UNISOL Mytex flat sheet backwashable membranes
• Huber
• Microdyn-Nadir/Mann+Hummel BioCel Membranes

By process configurations the MBR systems can be classified as:

•  Submerged MBR
•  Side Stream MBR (or external membrane)

For submerged MBR systems the Trans-membrane pressure is usually less than 0.5 bar (under vacuum pressure). The vacuum required for the mbr is usually from suctions pumps. Various types of pumps including centrifgal pump, gear pump, screw pump and helical rotor pumps can be used for this vacuum pumping purpose.

While for external membrane systems TMP of 1~4 bar is usual.

One typical MBR Process Flow Diagram is shown below. Raw wastewater usually pass through coarse screens and fine screens to remove particles that might possibly affect the downstream equipment and process. Membrane module can be immersed in the aeration tank itself or in a seprate membrane tank. Recirculation is utilized if denitrication is required for nitrogen nutrient removal.

Raw wastewater -> Fine Screens -> Denitrification -> Aeration -> Filtration -> Permeate

MBR system's advantages include the following:

• almost complete solids and bacteria (Giardia and Crypto) removal;
• high effluent quality; modular design with good expandability;
• robustness in recovery resistant to upsets due to shock loadings or peak and fluctuating flows;
• sludge age or SRT (solids retention time) and hydraulic residence time (HRT) are controlled separately;
• less odor;
• sophisticated but yet simple controls.

Some of the disadvantages of MBR technology are:

• membrane fouling
• higher energy consumption to overcome trans-membrane resistance and to prevent fouling using aeration etc
• high cost of membranes

Wastewater Engineering Group's expertise in Membrane Bioreactor Systems range from treatability studies to retrofit of existing systems, we have vast design, operating experiences in MBR applications for sewage and industrial wastewater treatment.