Experimental study and mathematical modeling of biofiltration of volatile organic compound mixtures using biofilters

Abstract

Human economic activities cause emissions of various pollutants of an organic nature: butanol, butyl acetate, methanol, formaldehyde, phenol, benzene, toluene, xylene, etc. These compounds are emitted into the atmosphere from various enterprises of food, chemistry, wood processing industries, from motor transport, agricultural enterprises, etc. Therefore, when purifying air from these pollutants, it is necessary to apply efficient and inexpensive air-purification methods. In this dimension, biological air purification from the mixtures of VOC (Volatile Organic Compounds) is chosen from all the possible air-cleaning methods. An experimental biofilter with an activated charge of pine bark was developed at the Department of Environmental Protection of Vilnius Gediminas Technical University. In the course of experimental investigation it is determined that this air-purification method is efficient. The filter efficiency, when purifying air from the mixtures of VOC (butanol, butyl acetate and xylene), to a great extent depending on the nature and concentrations (up to 100 mg/m3) of pollutants injected, might reach up to 77–80 %. However, this is not the final assessment of biofilter functioning. A mathematical model of a biofilter was developed on the basis of the investigation results with full consideration of physical, chemical and biological processes going on during the filter operation. The aim of the paper is to determine the biodegradation constant and absorption capacity preconditioning the efficiency of air cleaning, and to obtain half-empirical expressions of the filter efficiency.