Predicting MBR flow rates with qPCR microbial population monitoring

Flow through membranes in MBR systems determines wastewater charge rates.  Key parameters for MBR operation include:

• Flux - (L/m2/hr or GFD)
• Transmembrane Pressure (Bar or PSI)
• Permeability (LMH/Bar or GFD/PSI)

During operation, membrane pores become plugged with inorganics, particulates, and even microbial EPS.  While backflushing usually restores the membrane, the loss of flow while backflushing reduces the system charge rate.  

For the past year, Aster Bio has been working with an MBR system having issues with biomass EPS reducing flux rates through the membrane.  Using both Aster Bio's Microbial Community Analysis (MCA) and customized qPCR based on MCA results, the facility was able to:

• Identify the organisms responsible for problem EPS generation
• Use qPCR testing to monitor the populations and discover impact of operational changes on both "good" and "bad" microbial populations

In this case, the problem organisms were from the Thauera genera.  While often the most common genera in stable wastewater treatment systems, under select conditions certain groups of Thauera and Zooglea can produce excess EPS which increases transmembrane pressure and lowers permeability.  The challenge is identifying the genetic sequences for the problematic organisms (which are often system specific) and then correlating the high EPS production with operational data.  For this facility, Aster Bio determined that one group of Thauera were responsible for most loss of permeability and other Thauera were benign.  In the graph above, you can see that high percentages of Group 2 Thauera were strongly correlated with reduced permeability.