1. Biofiltration for the Treatment of Recalcitrant VOCs in Polluted Air Streams Sarah Mahon, PE Mane6960H01 Air & Water Pollution Control Engineering Fall 2013

2. The Problem http://www.bioremediation-specialists.com/Reductive-Processes.php

3. Solution: Soil Vapor Extraction http://commons.wikimedia.org/wiki/File:Conceptual_Diagram_of_Basic_Soil_Vapor_Extraction_(SVE)_System_for_Vadose_Zone_Remediation.png

4. Air Treatment Options for Destruction of VOCs Thermal oxidation (expensive, creates dioxins, constant fuel to maintain 1300-1500F) Catalytic oxidation (expensive, rare earth metals, constant fuel to maintain 600-800F) Activated carbon (expensive, frequent replacement of spent carbon) Biofilters (inexpensive, but can not treat all VOCs)

5. Biofiltration Dehalogenation (directly consume target contaminants) Dehalorespiration (use of halogenated compounds as electron acceptors in anaerobic respiration) Cometabolism (microbes breakdown compound while using another as a primary substrate) http://www.washoecounty.us/water/PCE_background.htm

6. Biofiltration Bioaugmentation (insert multiple strains of bacteria that breakdown specific compounds) UV Photodegredation (pretreatment – breakdown compounds into components easier for biofilter to digest)

7. Conclusions Need bacterial strains capable of breaking down toxic compounds Some degradation products more toxic than parent compounds, which can kill bacterial strains Some benchscale studies have shown success with cometabolism and UV pretreatment (few full-scale studies due to concerns) More research needed for certain types of recalcitrant VOCs