Modeling and Evaluation of Pollutant Emissions from Industrial Biofilters by Dispersion Models

Abstract

With gradually increasing strict environmental regulations that control emissions of volatile organic compounds (VOCs), reduced sulphur compounds and nuisance odors from industries, there is a growing need for air pollution control systems. Biofiltration systems have been widely used in the treatment of odorous and toxic volatile organic compounds. As compared to traditional physical and chemical systems, biofilteration is cost-effective, environmentally friendly, and highly efficient for many biodegradable pollutants. The biofilter concept is about using microorganisms to metabolize the variety of contaminants such as volatile organic compounds, reduced sulphur compounds and hydrocarbons. Although the biofilters are designed to eliminate pollutants with greater than 90% efficiency, accidental releases do occur due to biofilter failures; hence, this poses serious threats to health, especially to those who live in the vicinity of biofilter locations. This research investigates the dispersion of air pollutants that are accidentally released from industrial biofilters. Two commercial biofilters that were installed in different industrial sites, located in (Hickson) and (Toronto), Ontario, Canada, were used as test cases. A mathematical (Gaussian) dispersion model, a screening model (SCREEN3), and a non-steady state Lagrangian California Puff Model (CALPUFF), were used at different biofilter removal efficiencies to predict pollutant concentrations, dispersion and health effects, and to examine the impacts of topographical and meteorological conditions on concentration of pollutant emissions at receptor locations. The study shows that geographical variations (i.e., flat versus elevated surfaces) of the location of a biofilter have an effect on the wind, and hence on pollutant dispersion. The results confirmed that the iii wind direction has a direct impact on the pollutant plume path, whereas the wind speed and atmospheric stability class influence the pollutant concentration. The results elucidated that the high concentration of pollutants due to low removal efficiency of a biofilter can cause serious health problems. The results of this work can be used as a basis to evaluate biofilter performance under various atmospheric and geographical conditions and to improve biofilter design.