Removal of a Mixture of Formaldehyde and Methanol Vapors in Biotrickling Filters under Mesophilic and Thermophilic Conditions: Potential Application in Ethanol Production

Ethanol is a significant source of energy as a biofuel; however, its production using corn involves the generation of harmful emissions from both fermentation tanks and dryers. Scrubbers control the emissions from fermentation tanks, while the emissions from the dryers are controlled by regenerative thermal oxidizers. Potential alternatives to these energy- and water-intensive technologies are biotrickling filters (BTFs). In this study, two BTFs were operated in parallel to treat formaldehyde and methanol emissions in a volumetric ratio of 4:1, one at 25 degrees C (mesophilic), and the other at 60 degrees C (thermophilic). The mesophilic BTF simulated emissions from fermentation tanks, while the thermophilic BTF simulated emissions from dryers. Both beds were operated at an empty bed residence time of similar to 30 s and influent formaldehyde concentrations of 20, 50, and 100 parts per million per volume (ppmv). Formaldehyde polymerization was reduced in this study by adding NaOH to pH levels of 7.0-7.4 and heating the solution to a temperature of 60 degrees C. BTFs have successfully removed formaldehyde at typical ethanol plants emissions similar to 21 ppm(v). The BTF technology have the potential in replacing the conventional air treatment methods used at ethanol plants.