(752c) Application of Biofilter System for Removal of Ethyl Acetate: Column and Kinetic Studies

Emissions of VOCs, ethyl acetate (EA) in particular, cause serious environmental and public health concerns. Ethyl acetate (EA) is a volatile organic compound (VOC) that is one of the high-priority toxic chemicals and large volumes of EA are emitted into the atmosphere from various paints and solvent industries. The inhalation of vapors of ethyl acetate can cause severe irritation of mucous membranes and upper respiratory tract. Exposures to high concentrations of EA may cause liver and kidney damage. Thus streams polluted with the vapors of EA needs to be treated before being released into the atmosphere. The choice of treatment technique depends on the total cost of treatment method, nature of pollutant being treated, concentration and flow rate of the pollutant, and the mode of emissions of the gaseous waste streams & effluent streams. Thus bio-based techniques, especially biofiltration, is considered to be one of the better options for the removal of low to medium concentration of organic pollutants. Biofiltration incorporates all the basic processes such as adsorption, absorption, degradation and desorption of gaseous phase contaminants. The process of biofiltration has the advantage of metabolic and physiological flexibility, as well as the high adaptability of the populations of microbial species to consume the organic pollutants as a carbon source for its growth.

In this study, the performance of biofilter column was evaluated for the removal of EA using a mixture of matured compost and coal in the ratio of 2:1. The effect of various operational parameters such as inlet load, column bed height, packing material and shock loading conditions on the performance of biofilter column was investigated experimentally. The performance of biofilter was observed in terms of elimination capacity for the removal of EA by performing the experiments at different inlet loads during 45 days of biofilter operation. The value of microbial concentration obtained at the end of 15^th day was 3.64x10⁶ CFU g^-1 which represented a reasonably good growth of microorganisms and hence biofiltration study was continued till 45 days. The high microbial concentration (5.12X10⁸ CFU g^-1 of packing material) which was obtained after 45 days of biofilter operation was one of the reasons for carrying out the studies under shock loading conditions. The biofilter column was subjected to different loads varying from 23 to 53 g m^-3h^-1. The value of microbial concentration was increased to a value of 5.12x108 CFU g^-1 of packing material, with an increase in the operation time from 15 to 45 days. The reasonably good value of microbial concentration obtained was responsible for attaining the removal efficiency of around 92% during the shock loading study. The experimental results were validated with the Ottengraf-vanden Oever and Michaelis-menten kinetic models for explaining the mechanism of biofiltration. The maximum elimination capacity (EC) achieved was 32.66 g m^-3 h^-1 at an inlet load of 36 g m^-3 h^-1.