Mathematical modeling of biofiltration in activated pine-bark charge of a biofilter |
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Authors: | Vaiskunaite Rasa Baltrenas Pranas Spakauskas Valdas |
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Institution: | (1) Assoc. Prof. Dr. Rasa Vaiškunaitė Environment Protection DepartmentEnvironmental Engineering FacultyVilnius Gediminas Technical UniversitySaulėtekio al. 11, 2-21110223 Vilnius-40LITHUANIA,;(2) Prof Dr habil Pranas Baltrėnas Vilnius Gediminas Technical University Environmental Engineering Faculty Environmental Protection Department Saulėtekio al. 11, 2-308 LT-2040 Vilnius Lithuania,;(3) Assoc Prof Dr Valdas Špakauskas Vilnius Gediminas Technical University Faculty of Fundamental Sciences Department of Physics Saulėtekio al. 11 LT-2040 Vilnius Lithuania, |
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Abstract: | Aim, Scope and Background 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 to atmosphere by various enterprises of food, chemistry,
wood processing industries, from transportation means, agricultural enterprises, etc. Therefore, when purifying air from these
pollutants, it is necessary to apply efficient and inexpensive air purification methods. In this dimension, the biological
air purification is chosen from all possible air cleaning methods. An experimental biofilter with the activated charge of
pine bark was developed at the Department of Environment Protection of the Vilnius Gediminas Technical University. In the
course of the experimental investigation, it was determined that this air purification method is efficient. Filter efficiency,
when purifying air of volatile organic compounds (butanol, butyl acetate and xylene), to a great extent, depending on the
nature and concentrations (up to 100 mg/m3) of pollutants injected, might go up to
70-98%. The mathematical model of the biofilter was developed based on the research results and fully taking into consideration
physical, chemical, and biological processes going on during its operations.
Main Features The aim of this article is to determine biodegradation constant , absorption capacity , and half empiric expressions of
filter efficiency. Knowing this, it is possible to find out the dependence of the filter efficiency on the operational parameters
of the filter (i.e. on the concentrations and the height of biocharge of the initial pollutants (butanol, butyl acetate, xylene)
fed through it).
Conclusions With the help of mathematical modeling, the biodegradation constants and absorption capability of volatile organic compounds
(butanol, butyl acetate, and xylene) fed into the biofilter charged with the activated pine bark and used for the cleaning
of volatile organic compounds, as well as the efficiency of the biofilter in half empiric expression, have been established.
It has been discovered that the constant of pollutant biodegradation is a value inverse to the time during which the amount
of pollutants in the filter becomes times higher. It is rather complicated to carry out theoretical calculation of the biodegradation
constant at a molecular level, therefore this constant has been established based on the results obtained in the course of
research. The equations describing pollutant dynamics in the filter charge and the air cleaning processes going on in it have
been derived from diffusion equations in a mobile medium. The modeling helped to find out the absorption capacity of the
examined pollutants, which by its numeric value is equal to the volume unit of the absorbed gas amount. The latter factor,
the same as the biodegradation constant, was determined basing on the experimental results. Mathematical modeling brought
a range of formulas expressing dependences of each pollutant's efficiency on its initial concentrations and filter charge
height.
Recommendation /Outlook. Based on the experimental data, a mathematical model has been developed which will allow the measuring of the filter
efficiency not only with regard to the absorption and biodegradation of the pollutants under examination, but also with regard
to other pollutants and their compounds, etc., having an impact on the filter performance. The results of the mathematical
modeling have revealed that the modeling of processes going on in the filter is much simpler than isthe performance of long
and costly experiments. The developed mathematical model makes it possible to measure the filter efficiency at the present
moment. |
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Keywords: | biocharge absorption capacity biofilter constant of biodegradation mathematical modeling volatile organic compounds |
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