Technologies: Membrane Bioreactor (MBR)


Wehrle MBR systems rank among the most efficient biological wastewater treatment plants. By using membrane filtration to separate biomass from the treated effluent, it is possible to achieve an extremely compact construction, high standards of treatment and an effluent completely free of micro-organisms. These are only a few of the many advantages of this technology.

Wehrle MBR systems are provided in one of the four following configurations:

In the 1980's Wehrle Werk AG, the University of Stuttgart and Rheinland-Westfalen College in Germany developed the basis of membrane bioreactor technology. The first full scale Wehrle MBR-HS treatment plant, based on the results of this collaborative research, was conceived and in operation in 1992.

UF energy consumption

By reason of the then high membrane costs, the first treatment plants were built with a specific membrane area energy consumption of 800 to 1000 W/m2 of membrane area. However, energy costs were generally favourable since the utilisation of landfill gas, on the many landfill sites on which these plants were installed, provided a cheap source of energy.

UF membrane hollow fibres

In 2003 the first Wehrle MBR-LS plant was built, with a reduced energy consumption of only 150 W/m2 of membrane area.

Further development of membranes and modules has led to external membranes becoming an economic alternative in municipal wastewater treatment.

As a medium-sized engineering company, Wehrle Environmental has an independent choice of membrane configuration and materials. This flexibility allows us to find the most technically optimal and economical solution.

With over 100 full scale references worldwide, Wehrle is the market leader of membrane bioreactor plants with external membranes.

In MBR systems, no clarifiers are required as separation of solids takes place using UF membranes rather than clarification. Treated effluent quality from MBR systems is of a superior quality.

Wehrle’s MBR design is based on a modular concept with systems capable of being extended with additional membrane modules. Cross-flow tubular membranes are used, the activated sludge being pumped along the membrane surface, with a proportion recycled back through the feed pump and the remainder returned to the bioreactor. A proportion of the solids are filtered through the membrane wall, which provides an absolute barrier to form solids-free MBR permeate.

Aerators in typical bioreactor

Wehrle Environmental MBR systems generally ensure COD loadings of recalcitrant wastewater are reduced by up to 85-99%, the latter the norm for industrial food applications. By treating the permeate from the MBR by tertiary treatment technologies such as UV and/or Nanofiltration, treated water COD can be reduced to below 10 mg/l. Ammonia levels at up to 2000 mg/l can be reduced to less than 5 mg/l, and suspended solids are reduced to non-detectable levels. By using combinations of post-treatment technologies, MBR permeate can be processed to meet the necessary quality standards.