Effect of a Ternary Mixture of Volatile Organic Compounds on Degradation of TCE in Biotrickling Filter Systems
2016
Chheda, Dhawal | Sorial, George A.
The primary goal of this research was to evaluate the effect of a ternary mixture of toluene, methanol, and trichloroethylene (TCE) on the elimination of TCE in a biotrickling filter. Two biotrickling filters—Biofilter I and Biofilter II—were run in parallel, each with a different toluene/methanol/TCE loading ratio of 3:2.7:1 and 1.9:0.9:1, respectively. Both systems were seeded with fungal strains grown on diatomaceous earth media and were run at pH 4 maintained by formate buffer. To control excess biomass growth, the systems were “starved” for 2 days a week and run continuously for the rest of the week. TCE loading rates for each system ranged from 1.61 to 6.44 g/m³ h⁻¹ across three phases while toluene and methanol were loaded at rates corresponding to the influent composition ratios. More than 95 % methanol was removed from the gaseous streams throughout, while TCE removal was a function of the influent organic ratio and the corresponding concentrations. At and above loading rates of 3.22 g/m³ h⁻¹, elimination capacities obtained from Biofilter II surpassed those from Biofilter I due to a lower feed of bio-accessible carbon (toluene and methanol) offering reduced competition to TCE removal. While over 90 % toluene was removed from both systems, its elimination capacities dropped as the phases progressed due to competition and TCE cytotoxicity. Most carbon was converted to CO₂ and biomass, and no TCE oxidation by-products were detected.
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