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Membrane Bioreactor

Membrane bioreactors

The Membrane Bioreactor or MBR is based on the conventional wastewater process, but the separation of micro-organisms is performed by filtration with membranes.

3d MBR skid

3D drawing of a crossflow membrane skid

The MBR has some distinctive advantages compared with the conventional treatment systems:

•    Very stable process
The conventional biological system is sensitive to the wastewater composition. Due to variations in wastewater composition and/or presence of complex or toxic substances, high salt concentrations or low oxygen concentrations, the biomass floc formation is poor and the settling process will not perform well. This results in discharge of the micro-organisms and poor effluent quality.
The membranes will however withhold all biomass and other suspended solids, ensuring a high effluent quality.

•    Very compact design
Due to the membrane separation the active micro-organism population in the bioreactor can be maintained at a concentration 4-5 times higher than in conventional systems. This results in bioreactor tank volumes of only 20-25% of the size of conventional systems. A clarifier, being a space-consuming tank, is not required.

•    High effluent quality
The ultra filtration membranes withhold all micro-organisms and most suspended solids, resulting in a clear and highly purified effluent. The effluent may be reused as low-grade process water or for irrigation purposes.

•    Low sludge production
The MBR can operate at a low F/M ratio, being the Feed of organic substance per amount of Micro-organisms per time unit. This results in a high mineralisation of sludge. In conventional systems 1 kg COD will result in about 0,3 -0,4 kg of biomass. With MBR systems 1 kg COD is converted to 0 - 0,2 kg biomass (zero biomass production can be obtained when operating at high temperatures). The discharge of biomass can have significant impact on the operational costs of the system.
•    Treatment wastewater up to 60 °C is possible
•    Treatment of wastewater with chlorine concentrations up to 120 g/l
•    Insentive to shock and vibration (on board of ships)

Field of Application:
•    Poorly degradable water (lightly sludge-sensitive) 
•    In limited space 
•    Stringent discharge regulations 
•    Reuse

50M3 submerged mbrTwo versions of the MBR process are offered, the MemTriq® and the SubTriq®. The MemTriq® is based on a cross-flow filtration process. The biomass is filtered in a filtration unit besides the bioreactor. The SubTriq® is based on filtration with submerged membranes that are submerged in the biomass either in the bioreactor it self or in a separate tank.

50 m3/d submerged MBR system, reusing black water for toilet flushing in an office building

For publications of succesfull MBR applications see below links

Wastewater treatment on board of naval vessels

MBR systems in the offshore industry


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