Partitioning of BTEX constituents and chloroorganics in high-biomass systems

Henry's Law controls mass transfer rates for sparingly soluble organics and/or lower inlet VOC concentrations within a biofilter. We report measurements of apparent Henry's Law partitioning values for benzene, toluene, TCE, and chloromethane in systems that contain varying levels of biomass. The apparent air/liquid partition constant for benzene decreased from 2.9 × 10−3 atm m3 mol−1 to as low as 0.1 × 10−3 atm m3 mol−1 when biomass, in the form of yeast, was added to aqueous batch systems containing benzene. The constant for toluene decreased from 6.4 × 10−3 to 0.17 × 10−3 atm m3 mol−1. For TCE, the air/liquid partition constant decreased from 0.013 atm m3 mol−1 to less than 0.00013 atm m3 mol−1. Experimentally measured partition values were also used to calculate intrinsic “pure biomass” partitioning constants, which can be used to interpolate behavior. Apparent partitioning values for TCE were most heavily impacted by biomass levels, changing by two orders of magnitude. These data should allow other researchers to estimate and extrapolate the influence of biomass on their own biofiltration processes.