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Biofiltration of Chloroform in a Trickle Bed Air Biofilter Under Acidic Conditions
Palanisamy, K., B. Mezgebe, G. Sorial, AND E. Sahle-Demessie. Biofiltration of Chloroform in a Trickle Bed Air Biofilter Under Acidic Conditions. WATER, AIR, & SOIL POLLUTION. Springer, New York, NY, 227:478, (2016).
Chloroform is volatile hazardous chemical emitted from publicly owned treatment works (POTWs), cooling towers, pulp and paper mills, hazardous waste sites and sanitary landfills Chloroform persists as a fairly stable, non-reactive compound in the atmosphere for about 0.5 yr. causing long-range air pollution. This study investigated the effect of fungi and cometabolism on the performance of the tickle bed air biofilter for the stable removal of chloroform air streams. The results of this study prove that a trickle bed air biofilter is an effective medium to treat gas phase chloroform through cometabolism under suitable environmental conditions.
In this paper, the application of biofiltration is investigated for controlled removal of gas phase chloroform through cometabolic degradation with ethanol. A trickle bed air biofilter (TBAB) operated under acidic pH 4 is subjected to aerobic biodegradation of chloroform and ethanol. The TBAB is composed of pelleted diatomaceous earth filter media inoculated with filamentous fungi species, which served as the principle biodegrading microorganism. The removal efficiencies of 5 ppmv of chloroform mixed with different ratios of ethanol as cometabolite (25, 50, 100, 150, and 200 ppmv) ranged between 69.9 and 80.9%. The removal efficiency, reaction rate kinetics, and the elimination capacity increased proportionately with an increase in the cometabolite concentration. The carbon recovery from the TBAB amounted to 69.6% of the total carbon input. It is postulated that the remaining carbon contributed to excess biomass yield within the system. Biomass control strategies such as starvation and stagnation were employed at different phases of the experiment. The chloroform removal kinetics provided a maximum reaction rate constant of 0.0018 s−1. The highest ratio of chemical oxygen demand (COD)removal/nitrogenutilization was observed at 14.5. This study provides significant evidence that the biodegradation of a highly chlorinated methane can be favored by cometabolism in a fungi-based TBAB.