Exhaust Gas Monitoring from MABR: A New Alternative for Biological Process Control

The increasing adoption of MABR in the wastewater treatment industry is leading to new understandings of behavior under field conditions. One example is the unique behavior of MABR biofilms under diurnal load variations. The natural Ammonia-Based-Nitrification-Control (ABNC) of counter-diffusional MABR biofilms is explored with respect to its potential for process monitoring and process control. Process monitoring because mixed liquor ammonia concentrations can be directly correlated to MABR exhaust oxygen. MABR exhaust gas monitoring can therefore provide a low-cost alternative, or complement, to immersed liquid ammonia sensors. Process control because knowledge and insights from exhaust oxygen monitoring can be used to better optimize, in hybrid systems, the synergistic balance between biofilm and mixed liquor nitrification. The resilience of MABR-based process monitoring and control is highlighted. Exhaust gas sensors, which are kept “high and dry”, are found to be more reliable than liquid sensors, which are subjected to the corrosive environment of wastewater and mixed liquor.