Membrane Biofilm Reactors

The hydrogen-based Membrane Biofilm Reactor (MBfR) reduces oxidized pollutants in water


A lab-scale OpenCEL unit

Many emerging water pollutants share a common characteristic:  they are chemically oxidized.  These include perchlorate, selenate, chromate, and the chlorinated solvents.  Also among the oxidized contaminants are nitrate and nitrite.  Bacteria that oxidize hydrogen gas (H2) are able to reduce all of the oxidized contaminants, turning them into harmless materials, such as chloride ion, nitrogen gas, and water.  The challenge is finding a means to deliver the H2 to the bacteria in an efficient manner, since H2 has very low water solubility and also is combustible.  Invented by Dr. Rittmann, the membrane biofilm reactor (MBfR) is the technological breakthrough that makes H2 deliver simple and efficient.  H2 gas is provided to the core of small hollow-fiber membranes at a controlled pressure.  The H2 molecules diffuse through the fiber walls and are consumed by a biofilm of H2-oxidizing bacteria that liver as a biofilm on the fibers’ outside surface.  

Using all of the tools available for biofilm research, Swette Center researchers are exploring the ecological and kinetic fundamentals of MBfR biofilms in a wide range of settings.  Current studies emphasize how to manage the biofilm communities so that desired reductions occur efficiently, while undesired ones are prevented.  For example, we are developing the means to promote the reduction of perchlorate, but to preclude the reduction of sulfate.  Likewise, we are learning what it takes to enhance the reductive dechlorination of trichloroethene (TCE) while eliminating methanogenesis.  

The MBfR is a patented, licensed, and commercialized technology.  It can be purchased today from APTwater under the ARoXXXX trade name, where ARo stands for “autotrophic reduction of” and XXXX designates the oxidized contaminant to be removed, such as NITE for nitrate and PERC for perchlorate.  Swette Center researcher cooperate with APTwater and leading consulting firms to test the MBfR in the field and develop new applications.