Low-Energy Nitrification of Wastewaters Using Membrane Aerated Biofilm Reactors
The membrane aerated biofilm reactor is a new energy-efficient technology that utilizes bubbles-less aeration to supply oxygen for biological nitrification and degradation of wastewater. GE Water & Process Technologies recently released a new oxygen-permeable hollow-fiber membrane specifically designed for use in membrane aerated biofilm reactors (MABRs). These fibers are organized into bundles which are wrapped around a reinforcing yarn core for strength. The design, marketed by GE as the Zeelung™ cord, not only provides a vast surface area for oxygen transfer, but includes the strength and durability needed for industrial uses. The purpose of this study was to evaluate the performance of MABRs using ZeeLung™ cords. Synthetic influents with a range of COD/N ratios from 1.3 to 4.6 were prepared and tested at multiple loading rates to determine the impact on nitrification, oxygen transfer, and biofilm composition. Experimental results demonstrated nitrification and oxygen transfer abilities of up to 6.5 g/m2/d and 20.0 g/m2/d, respectively for the experimental test conditions. Results also showed that increasing the COD/N ratio up to 4.6 by increasing the glucose concentration in the feed resulted in substantial heterotrophic growth, which inhibited nitrification but increased denitrification of any nitrified effluent.