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Atmosphere protection using biological methods to remove wide mixtures of VOCs from waste air
Goal: Biofiltration is one of the promising waste air treatment technologies. Thus the project will evaluate biofilter operation effectively mimicking conditions frequently encountered in relevant industrial applications including the application of model pollutant mixtures and combined reactors.
Novelty: Disconnect between academic studies and real-world problems, i.e., in the application of pollutant mixtures and combined reactors, will be addressed by studying these industrially relevant systems under controlled lab conditions.
Broader impacts: The targeted application of real pollutant mixtures and conditions frequently encountered in industrial applications will enable improvement of the efficiency of real-world industrial processes and bioreactors for exhaust air cleanup.
Background: A common limitation of published feasibility studies on biofiltration is their focus on only one pollutant. However, this is not realistic, as removal of complex mixtures (instead of a single component) that are frequently encountered in industrial applications adds a number of different variables that must be further studied. The factors having adverse effects were for example: an interaction of compounds in a mixture during their degradation (toxicity, diauxic effects), accumulation of polar compounds in the bioreactor aquatic phase of causing toxic effects and oxygen depletion, stripping of such accumulated compounds back into the outlet air and rapid pH drops.
Various bioreactors/biotechniques, e.g., biofilters and biotrickling filters have been studied extensively, with each of these two classical reactors/processes having inherent advantages and disadvantages. However, synergies arising from the integration of reactors/processes, i.e., combined technologies, could be used for the improvement of waste air treatment. Bioreactor combinations, e.g., biofilter-biofilter, trickling filter-biofilter, bioscrubber-biofilter or adsorption pre-treatment-bioreactor and UV pre-treatment-bioreactor can be envisioned. Integrated processes have been shown to be more efficient for many practical conditions that are frequently encountered in industrial applications, particularly when the system exceeds its biological limit, due to pollutant toxicity, inhibitory pollutant concentration, long-term non-use periods, fluctuations in pollutant concentrations and/or air flow rates transient shock-load conditions
Methods: This project will be conducted in lab-scale combined technology during their long-term operation. Specific reactor configuration and specific pollutant composition will be selected for this project on the basis of the actual experimental work occurring at the moment in our reactor lab, starting with a study of promising bubble column-biofilter combined system treating a mixture of hydrophobic and hydrophilic pollutants. The bioreactors are equipped with advanced measurement and control systems allowing semi- unattended operation. pH and dissolved oxygen level are measured automatically. However to obtain key information about degradation the monitoring of pollutants and metabolites in the incoming and outgoing gas and aquatic phase have to be conducted with more efficient offline methods. This will be the student responsibility, along with the primary analysis of the observed effects and suggestion of the next steps. The work will be based on setting the selected parameters and measurement of system performance using chromatographic methods. CG-FID and HPLC-DAD and HPLC-RI will be used for routine quantitative analyses of gaseous and liquid samples. GC-MS together with extraction (solvent extraction, SPE, MSPE available) and/or derivatization will be used for occasional qualitative analyses of gaseous and liquid samples. Also the biocatalyst (free cells or biofilm) characterization using microbial methods e.g., microscopy, cell staining will be conducted to complete the assessment of the results obtained. These analytical methods were previously used and described in our articles. Our group is interested in training students who are interested in analytical chemistry, as their complementary prior experience can improve the existing analysis methods or even lead to developing different approaches to sample analyses from bioreactors.