Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry

La industria de la pintura de automóviles es una fuente de contaminación ambiental causada por los compuestos orgánicos volátiles (COV) presentes en el aire de ventilación descargado. Para contribuir a la mitigación de este tipo de contaminación atmosférica, Ekoinwentyka Ltd. desarrolló -desde la es...

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Autores:: Kasperczyk, Damian
Urbaniec, Krzysztof
Barbusinski, Krzysztof
Rene, Eldon R.
Colmenares Quintero, Ramón Fernando

Tipo de recurso:: Article of investigation

Fecha de publicación:: 2021

Institución:: Universidad Cooperativa de Colombia

Repositorio:: Repositorio UCC

Idioma:

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network_acronym_str	COOPER2
network_name_str	Repositorio UCC
repository_id_str
dc.title.spa.fl_str_mv	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry
title	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry
spellingShingle	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry Compuestos orgánicos volátiles Biorreactor compacto de lecho de goteo Taller de pintura industrial Sistema de ventilación Biodegradación de contaminantes Volatile organic compound Compact trickle bed bioreactor Industrial painting shop Ventilation system Pollutant biodegradation
title_short	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry
title_full	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry
title_fullStr	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry
title_full_unstemmed	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry
title_sort	Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry
dc.creator.fl_str_mv	Kasperczyk, Damian Urbaniec, Krzysztof Barbusinski, Krzysztof Rene, Eldon R. Colmenares Quintero, Ramón Fernando
dc.contributor.author.none.fl_str_mv	Kasperczyk, Damian Urbaniec, Krzysztof Barbusinski, Krzysztof Rene, Eldon R. Colmenares Quintero, Ramón Fernando
dc.subject.spa.fl_str_mv	Compuestos orgánicos volátiles Biorreactor compacto de lecho de goteo Taller de pintura industrial Sistema de ventilación Biodegradación de contaminantes
topic	Compuestos orgánicos volátiles Biorreactor compacto de lecho de goteo Taller de pintura industrial Sistema de ventilación Biodegradación de contaminantes Volatile organic compound Compact trickle bed bioreactor Industrial painting shop Ventilation system Pollutant biodegradation
dc.subject.other.spa.fl_str_mv	Volatile organic compound Compact trickle bed bioreactor Industrial painting shop Ventilation system Pollutant biodegradation
description	La industria de la pintura de automóviles es una fuente de contaminación ambiental causada por los compuestos orgánicos volátiles (COV) presentes en el aire de ventilación descargado. Para contribuir a la mitigación de este tipo de contaminación atmosférica, Ekoinwentyka Ltd. desarrolló -desde la escala piloto hasta la escala completa- y adaptó la tecnología del biorreactor de lecho de goteo compacto (CTBB), cuyo principio de funcionamiento se basa en el flujo descendente de la fase gaseosa (aire contaminado) y la fase líquida (solución de sales minerales) a través de un lecho empacado en el que los microorganismos activos se inmovilizan en la biopelícula de las superficies de los elementos de empaquetado. El biorreactor a escala piloto de 0,32 m de diámetro y 1,50 m de altura total tenía su lecho empacado inoculado con un consorcio de microorganismos dominado por la bacteria Pseudomonas fluorescens. Durante el programa experimental, que duró varios meses, el caudal de aire extraído del sistema de ventilación del taller de pintura variaba entre 1,0 y 10,0 m3/h y la concentración de entrada de COV oscilaba entre 10 y 200 ppm. Al medir la concentración de COV en el aire purificado, se comprobó que el factor de biodegradación de los COV oscilaba entre el 85 y el 99%. A partir de los experimentos a escala piloto, se ha desarrollado un CTBB a escala real de 2,8 m de diámetro y 10 m de altura total y se ha instalado como componente adicional del sistema de ventilación del taller de pintura. Las pruebas realizadas con caudales de gas de hasta 6.000 m3/h confirmaron un factor de biodegradación de COV del 85-99%, lo que demuestra un resultado positivo de la adaptación de la tecnología CTBB a las condiciones de la industria de la pintura de automóviles.
publishDate	2021
dc.date.accessioned.none.fl_str_mv	2021-05-20T19:06:35Z
dc.date.available.none.fl_str_mv	2021-05-20T19:06:35Z 2022-06-09
dc.date.issued.none.fl_str_mv	2021-05-09
dc.type.none.fl_str_mv	Artículos Científicos
dc.type.coar.none.fl_str_mv	http://purl.org/coar/resource_type/c_2df8fbb1
dc.type.coarversion.none.fl_str_mv	http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.driver.none.fl_str_mv	info:eu-repo/semantics/article
dc.type.version.none.fl_str_mv	info:eu-repo/semantics/publishedVersion
format	http://purl.org/coar/resource_type/c_2df8fbb1
status_str	publishedVersion
dc.identifier.issn.spa.fl_str_mv	09596526
dc.identifier.uri.spa.fl_str_mv	https://doi.org/10.1016/j.jclepro.2021.127440
dc.identifier.uri.none.fl_str_mv	https://hdl.handle.net/20.500.12494/34345
dc.identifier.bibliographicCitation.spa.fl_str_mv	Kasperczyk, D., Urbaniec, K., Barbusiński, K., Rene, E., & Colmenares-Quintero, R. (2021). Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry. Journal of Cleaner Production, 309, 127440–. https://doi.org/10.1016/j.jclepro.2021.127440
identifier_str_mv	09596526 Kasperczyk, D., Urbaniec, K., Barbusiński, K., Rene, E., & Colmenares-Quintero, R. (2021). Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry. Journal of Cleaner Production, 309, 127440–. https://doi.org/10.1016/j.jclepro.2021.127440
url	https://doi.org/10.1016/j.jclepro.2021.127440 https://hdl.handle.net/20.500.12494/34345
dc.relation.isversionof.spa.fl_str_mv	https://bbibliograficas.ucc.edu.co:2152/science/article/pii/S0959652621016590?via%3Dihub
dc.relation.ispartofjournal.spa.fl_str_mv	Journal of Cleaner Production
dc.relation.references.spa.fl_str_mv	Álvarez-Hornos et al., 2011 F.J. Álvarez-Hornos, C. Lafita, V. Martínez-Soria, J.M. Penya-Roja, M.C. Pérez, C. Gabaldón Evaluation of a pilot-scale biotrickling filter as a VOC control technology for the plastic coating sector Biochem. Eng. J., 58–59 (2011), pp. 154-161 Bak et al., 2017 A. Bak, V. Kozik, P. Dybal, S. Sułowicz, D. Kasperczyk, S. Kus, K. Barbusinski Abatement robustness of volatile organic compounds using compact trickle-bed bioreactor: biotreatment of styrene, ethanol and dimethyl sulfide mixture in contaminated airstream Int. Biodeterior. Biodegrad., 119 (2017), pp. 316-328 Barbusinski et al., 2017 K. Barbusinski, K. Kalemba, D. Kasperczyk, K. Urbaniec, V. Kozik Biological methods for odor treatment - a review J. Clean. Prod., 152 (2017), pp. 223-241 Brancher et al., 2017 M. Brancher, K.D. Griffiths, D. Franco, H. de Melo Lisboa A review of odour impact criteria in selected countries around the world Chemosphere, 168 (2017), pp. 1531-1570 Brinkmann et al., 2016 T. Brinkmann, G. Giner Santonja, H. Yükseler, S. Roudier, L. Delgado Sancho Best available techniques (BAT) reference document for common waste water and waste gas treatment/management systems in the chemical sector Available at https://eippcb.jrc.ec.europa.eu/reference (2016) Cox and Deshusses, 2001 H.H.J. Cox, M.A. Deshusses Biotrickling filters C. Kennes, M.C. Veiga (Eds.), Bioreactors for Waste Gas Treatment, Kluwer, Dordrecht (2001), pp. 133-162 Cui et al., 2020 P. Cui, G. Schito, Q. Cui VOC emissions from asphalt pavement and health risks to construction workers J. Clean. Prod., 244 (2020), p. 118757 Delvigne and Lecomte, 2010 F. Delvigne, J. Lecomte Foam formation and control in bioreactors M.C. Flickinger (Ed.), Encyclopedia of Industrial Biotechnology: Bioprocess, Bioseparation, and Cell Technology, Wiley (2010) Diks and Ottengraf, 1991 R.M.M. Diks, S.P.P. Ottengraf Verification studies of a simplified model for the removal of dichloromethane from waste gases using a biological trickling filter Bioprocess Eng. Part I, 6 (1991), pp. 93-99 Part II vol. 6, 131-140 Gąszczak et al., 2018 A. Gąszczak, G. Bartelmus, A. Rotkegel, R. Sarzynski Experiments and modelling of a biotrickling filter (BTF) for removal of styrene from airstreams J. Chem. Technol. Biotechnol., 93 (9) (2018), pp. 2659-2670 Gospodarek et al., 2019 M. Gospodarek, P. Rybarczyk, B. Szulczynski, J. Gębicki Comparative evaluation of selected biological methods for the removal of hydrophilic and hydrophobic odorous VOCs from air Processes, 7 (2019), p. 187 Kasperczyk and Urbaniec, 2015 D. Kasperczyk, K. Urbaniec Application of a compact trickle-bed bioreactor to the biodegradation of pollutants from the ventillation air in a copper-ore mine J. Clean. Prod., 87 (2015), pp. 971-976 Kasperczyk et al., 2019 D. Kasperczyk, K. Urbaniec, K. Barbusiński, E.R. Rene, R.F. Colmenares-Quintero Application of a compact trickle-bed bioreactor for the removal of odor and volatile organic compounds emitted from a wastewater treatment plant J. Environ. Manag., 236 (2019), pp. 413-419 Kasperczyk et al., 2019 D. Kasperczyk, K. Urbaniec, K. Barbusiński, E.R. Rene, R.F. Colmenares-Quintero Application of a compact trickle-bed bioreactor for the removal of odor and volatile organic compounds emitted from a wastewater treatment plant J. Environ. Manag., 236 (2019), pp. 413-419 Kennes et al., 2009 C. Kennes, M. Montes, M.E. López, M.C. Veiga Waste gas treatment in bioreactors: environmental engineering aspects Can. J. Civ. Eng., 36 (2009), pp. 1887-1894 Kennes and Thalasso, 1998 C. Kennes, F. Thalasso Waste gas biotreatment technology J. Chem. Technol. Biotechnol., 72 (1998), pp. 303-319 Kirchner et al., 1996 K. Kirchner, S. Wagner, H.-J. Rehm Removal of organic air pollutants from exhaust gases in the trickle-bed bioreactor. Effect of oxygen Appl. Microbiol. Biotechnol., 45 (1996), pp. 415-419 Lafita et al., 2012 C. Lafita, J.‐M. Penya‐Roja, C. Gabaldón, V. Martínez‐Soria Full‐scale biotrickling filtration of volatile organic compounds from air emission in wood‐coating activities J. Chem. Technol. Biotechnol., 87 (2012), pp. 732-738 Liao et al., 2018 D. Liao, E. Li, J. Li, P. Zeng, R. Feng, M. Xu, G. Sun Removal of benzene, toluene, xylene and styrene by biotrickling filters and identification of their interactions PloS One, 13 (2018), Article e0189927 Mudliar et al., 2010 S. Mudliar, B. Giri, K. Padoley, D. Satpute, R. Dixit, P. Bhatt, R. Pandey, A. Juwarkar, A. Vaidya Bioreactors for treatment of VOCs and odours – a review J. Environ. Manag., 91 (2010), pp. 1039-1054 Oyarzun et al., 2019 P. Oyarzun, L. Alarcón, G. Calabriano, J. Bejarano, D. Nuñez, N. Ruiz-Taglec, H. Urrutia Trickling filter technology for biotreatment of nitrogenous compounds emitted in exhaust gases from fishmeal plants J. Environ. Manag., 232 (2019), pp. 165-170 Rybarczyk et al., 2019 P. Rybarczyk, B. Szulczyński, J. Gębicki, J. Hupka Treatment of malodorous air in biotrickling filters: a review Biochem. Eng. J., 141 (2019), pp. 146-162 Salamanca et al., 2017 D. Salamanca, D. Dobslaw, K.H. Engesser Removal of cyclohexane gaseous emissions using a biotrickling filter system Chemosphere, 176 (2017), pp. 97-107 San-Valero et al., 2018 P. San-Valero, A.D. Dorado, V. Martínez-Soria, C. Gabaldón Biotrickling filter modeling for styrene abatement. Part 1: model development, calibration and validation on an industrial scale Chemosphere, 191 (2018), pp. 1066-1074 San-Valero et al., 2019 P. San-Valero, C. Gabaldón, F.J. Álvarez-Hornos, M. Izquierdo, V. Martínez-Soria Removal of acetone from air emissions by biotrickling filters: providing solutions from laboratory to full-scale J. Environ. Sci. Health A Tox Hazard Subst. Environ. Eng., 54 (1) (2019), pp. 1-8 Search ScienceDirect Outline Abstract Keywords 1. Introduction 2. Materials and methods 3. Results and discussion 4. Discussion 5. Conclusions CRediT authorship contribution statement Declaration of competing interest Acknowledgements References Figures (10) Fig. 1. Simplified scheme of the laboratory setup for CTBB tests: 1) Blower 2) Valves,… Fig. 2. Photograph of the laboratory setup Fig. 3. Stages of delivery, assembly, and commissioning of CTBB at the industrial site Fig. 4. CTBB and its control panel during the tests of bio-purification of air Fig. 5. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg=2 Fig. 6. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg=5m3/h;… Elsevier Journal of Cleaner Production Volume 309, 1 August 2021, 127440 Journal of Cleaner Production Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry Author links open overlay panelDamianKasperczykaKrzysztofUrbaniecbKrzysztofBarbusińskicEldon R.RenedRamon F.Colmenares-Quinteroe https://doi.org/10.1016/j.jclepro.2021.127440Get rights and content Abstract The automotive painting industry is a source of environmental pollution caused by Volatile Organic Compounds (VOCs) present in the discharged ventilation air. To contribute to the mitigation of this type of air pollution, Ekoinwentyka Ltd. developed – from pilot scale to full scale – and adapted the technology of Compact Trickle Bed Bioreactor (CTBB) whose operating principle builds upon co-current downflow of the gas phase (polluted air) and liquid phase (solution of mineral salts) through a packed bed where active microorganisms are immobilized in the biofilm on the surfaces of packing elements. Pilot-scale bioreactor 0.32 m in diameter and 1.50 m total height had its packed bed inoculated with a consortium of microorganisms dominated by Pseudomonas fluorescens bacteria. During the experimental programme that lasted several months, the flow rate of air drawn from the ventilation system of the painting shop was changing between 1.0 and 10.0 m3/h and the inlet concentration of VOCs ranged from 10 to 200 ppm. By measuring VOC concentration in the purified air, the factor of VOC biodegradation was found to range between 85 and 99%. Based on pilot-scale experiments, full-scale CTBB has been developed 2.8 m in diameter and 10 m total height and installed as an add-on component of the ventilation system of the painting shop. Test operation at gas flow rates up to 6000 m3/h, confirmed VOC biodegradation factor at the level of 85–99% thus proving a positive result of CTBB technology adaptation to the conditions of the automotive painting industry. Previous article in issueNext article in issue Keywords Volatile organic compoundCompact trickle bed bioreactorIndustrial painting shopVentilation systemPollutant biodegradation 1. Introduction Volatile Organic Compounds (VOC's) constitute one of the most important groups of pollutants that are emitted from industrial activities to the atmosphere (Cui et al., 2020) and may pose a great exposure risk to surrounding residents (Zhang et al., 2020). Apart from being odorous and toxic, these substances as precursors of photochemical oxidation are responsible for the formation of tropospheric ozone and the occurrence of smog (Speight, 2018). To avoid violation of emission standards (Brancher et al., 2017), it may be necessary to remove VOC's from industrial waste gases (Brinkmann et al., 2016). Various chemical and physical techniques of gas cleaning are available for the elimination of organic and other odorous compounds from waste gas streams (Wysocka et al., 2019). A broad spectrum of compounds can be removed using chemical methods, however, they are energy intensive and/or necessitate the use of chemicals. If waste gases are treated by physical methods, then pollutants are shifted to solid or liquid sorbents, and the subsequent regeneration of these results often in the creation of a new pollutant. As a more sustainable alternative, energy efficient and environment friendly biological techniques employing indigenous bacteria can be applied for the removal of VOCs from waste gases as indicated by Kennes and Thalasso (1998), and extensively discussed in the book edited by Shareefdeen and Singh (2005). Reflecting the progress in research and the accumulation of industrial experience, the application potential of biological VOC removal was later evaluated by Thakur et al. (2011) and more recently, discussed by Barbusinski et al. (2017). As another option of environment friendly waste gas cleaning, VOC oxidation by discharge plasma may also be mentioned (Shang et al., 2019) but this is an emerging technology not yet ripe for industrial application. Odors and VOCs removal in simple biofilters with soil beds dates back to the 1950ties. At the turn of the 20th century, the application of more sophisticated biotrickling filters (BFs) was studied theoretically and experimentally (Diks and Ottengraf, 1991), and introduced to industries (Kirchner et al., 1996), including metal painting shops (Webster et al., 1999) where the cleaning of waste gases is a necessity. The advantages of BF technology for the biodegradation of VOCs were recognized (Cox and Deshusses, 2001) making for a continuation of this line of research (Álvarez-Hornos et al., 2011) and BF applications in the wood finishing and painting industry (Lafita et al., 2012). It is now widely understood that VOCs removal can be performed in biofilters, bioscubbers, and biotrickling filters. A specific equipment type is usually selected depending on its range of economic application (Mudliar et al., 2010) but when the application requires operational flexibility of the equipment, biotrickling filters – also known as trickle-bed-bioreactors – are preferred providing also the advantage of compactness and moderate cost (Rybarczyk et al., 2019). However, as pointed out by Oyarzun et al. (2019), biotrickling filtration still is considered an innovative technology, and its transfer to new application areas is rather slow. In recent years, using laboratory or pilot scale BFs, researchers investigated biodegradation of individual VOC species including cyclohexane (Salamanca et al., 2017) and 1-butanol (Schmidt and Anderson, 2017), or VOCs mixtures exemplified by ones containing benzene, toluene, xylene, and styrene (Liao et al., 2018), and by waste gases from chemical fibre wastewater treatment plant (Yang et al., 2019). Full-scale application of BF technology for VOC biodegradation in the wood finishing and painting industry was reported by e.g., San Valero et al. (2019). The key component of a BF is its filter bed made of some synthetic or natural inert material on which active microorganisms are immobilized forming a biofilm. An aqueous phase (mineral salt solution) is trickled over the filter bed, while the gas phase to be cleaned flows in co- or counter-current through the bed. The pollutants to be removed are initially dissolved in the aqueous film that covers the biofilm and then diffused into the biofilm where biodegradation occurs (Kasperczyk et al., 2019). Given the above characteristics of BF operation, hydrophilicity or hydrophobicity of the pollutants should be accounted for in the selection of equipment for VOCs treatment (Gospodarek et al., 2019). As pointed out by Wu et al. (2018), the VOCs and odorants removal performance by BF may be limited by the hydrophobicity, toxicity, and low bioavailability of these pollutants. Therefore, the issues of selection and adaptation of microorganisms to the degraded pollutants are particularly important for this type of process. Understanding and modeling of the phenomena occurring in the BFs, as well as a detailed analysis of the biodegradation process, constitute the basis for their design, optimization, and maintenance of the BFs, as can be seen in a study on styrene removal from airstreams published by Gąszczak et al. (2018). A similar approach was adopted by San-Valero et al. (2018) in their investigations of styrene abatement. The present authors have previously investigated applications of a specific BF design to the elimination of hydrogen sulphide, and other odorous compounds from the streams of waste air discharged from a deep copper-ore mine (Kasperczyk and Urbaniec, 2015) and wastewater treatment plant (Kasperczyk et al., 2019). The bioreactor, developed by Ekoinwentyka Ltd, is known as the compact trickle-bed bioreactor (CTBB). In the present work, the attention is turned to CTBB application for the removal of VOCs, such as solvent vapors, emitted from the automotive painting industry. The aim of the research was twofold: - Firstly, to isolate microorganisms suitable for VOC removal and to test a pilot scale CTBB, inoculated with these microorganisms. The bioreactor was initially installed and tested in the company's laboratory and later moved to an industrial site where the tests were continued. By performing pilot-scale tests in the industrial plant, the efficiency of the microorganisms in degrading the VOCs was ascertained. - Secondly, based on the experience from the pilot scale, to develop and apply a full scale CTBB for the removal of VOCs from the ventilation air discharged from an industrial painting shop. Measurements and observations were made to evaluate the performance of CTBB, including the efficiency of VOC degradation, under industrial conditions where disturbances in process parameters may occur. Positive results of VOCs removal in the full-scale CTBB in the automotive painting shop constitute the main novelty of the present work. Upon the completion of bioreactor tests, the CTBB was put into commercial operation of the shop's ventilation system. 2. Materials and methods 2.1. Selection of microorganisms for VOC removal The process concept assumes the use of microorganisms naturally occurring at the place where pollutants are present. To achieve that, it is necessary to develop and apply procedures for isolation and selection of suitable bacterial strains followed by their adaptation to the target pollutants, and to optimize the conditions for the growth of bacterial flora. Potentially useful microorganisms are initially secured by collecting soil samples from industrial sites where automotive painting shops are in operation. In the next stage, a bacterial consortium capable of degrading VOCs is isolated using the enrichment culture technique. It requires supplying nutrients and creating environmental conditions for the growth of microorganism mixture so controlled as to favour the growth of bacterial strains that degrade the VOCs efficiently. Following the formation of a suitable microbial consortium, the final stage of the procedure is executed by exposing the consortium to the target pollutants at real-life concentration levels. The adaptation to the application conditions is completed when stable growth of the microorganisms has been observed during that stage. 2.2. Testing Compact Trickle Bed Bioreactor in pilot scale The pilot-scale tests were aimed to determine the optimal parameters of VOC biodegradation conducted in CTBB to achieve high efficiency of the process, as well as to acquire information needed for creating a data map that would allow upscaling this technology and implementing it in selected industrial painting shops. After inoculating the bioreactor bed with the selected microorganisms and securing biofilm formation on the bed packing, the pilot CTBB was ready for testing biodegradation of VOCs present in the air stream supplied to the bioreactor inlet. The set of relevant process parameters included, gas and liquid phase flowrates, VOCs concentrations in the gas stream at bioreactor inlet and outlet, gas residence time (dependent on the characteristics of bed packing), oxygen content in the mineral salt solution, temperature, pH, and physiological parameters of biomass formation in bioreactor bed. Apart from measuring these parameters, pilot studies conducted in the laboratory enabled verifying the choice of packing elements and estimating the relationship between the efficiency of VOCs biodegradation and changing process conditions. The scheme of laboratory setup in which the process of cleaning the air from volatile impurities was conducted is shown in Fig. 1. Its main component is the Compact Trickle Bed Bioreactor made of stainless steel with a diameter of 0.315 m and active bed 0.6 m high, packed with polypropylene Ralu Rings sized 15 × 15 mm. The gas phase in the tests was air pumped by a compressor (1). After passing through the filter system (4), the air was heated to about 25 °C (during test operation, the system was carefully thermostated) and supplied to the bioreactor. The solution of VOCs used in the industrial process of varnishing/painting was dosed by a micro-pump connected to a column packed with glass particles, where the VOCs evaporated to the main air stream. Pollutant concentration in the supplied gas was determined near the bioreactor inlet. The liquid phase circulating in the system was a solution of mineral salts (total volume around 25 L) whose parameters, including flowrate, pH, temperature, and absorbance (indicating the concentration of microorganisms in the solution) were controlled, and regulated on-line using auxiliary equipment such as micro-pumps dispensing buffer solutions, control valves and heaters. The liquid distributor (13) placed above the bioreactor bed ensured that gas and liquid flowing co-currently downwards were brought into contact over the packing surface. The concentration of pollutant remaining in the purified gas was determined after the discharged gas passed the droplet separator. Fig. 1 Download : Download high-res image (480KB)Download : Download full-size image Fig. 1. Simplified scheme of the laboratory setup for CTBB tests: 1) Blower 2) Valves, 3) Gas-phase control system 4) Pre-filter, 5) Gas flow meter, 6) Liquid source, 7) Droplet separator, 8) Liquid tank in bioreactor base, 9) Liquid level meter, 10) Inverter-controlled pump, 11) Liquid flow meter, 12) Pumps dispensing buffer solutions to maintain the required living environment for microorganisms, 13) Liquid distributor, 14) Pump, 15) Level-control valves, 16) Measurements of process-relevant parameters in the gas and liquid phases, G – bed support grate, S – sight glass, ---- liquid phase, --- gas phase. A photo of the laboratory setup including its control equipment is shown in Fig. 2. Before starting the process, to minimize the presence of microorganisms other than the selected ones, the entire setup was sterilized by rinsing three times with alcohol solution and irradiated for several hours using a UV lamp. This was followed by the immobilization of microorganisms on the packing of the bioreactor bed. To this end, microorganisms adapted to VOC degradation (mainly Pseudomonas fluorescens; more information is given in Section 3.1) were mixed with 10 L of the liquid phase, and the resulting suspension was circulated through the bed for around 3 days until changes in the absorbance of suspension occurred thus indicating the formation of biofilm layer on the packing. After that, the suspension was removed from the setup, the bed was rinsed with sterile mineral-salt solution, and the process was started by setting gas and liquid flowrates, and pollutant concentration in the gas supplied to the bioreactor. Fig. 2 Download : Download high-res image (514KB)Download : Download full-size image Fig. 2. Photograph of the laboratory setup. The VOC biodegradation setup was continuously operated in the laboratory for several months. By varying the flowrates of gas and liquid phases, different values were set of specific pollutant load Ms defined as: (1)Ms = Cgin / tg [g/(m3h)] where: Cgin – VOC concentration at bioreactor inlet [g/m3], and tg – average gas residence time: (2)tg = Vbed / Vg [h] where Vbed – empty bed volume [m3] and Vg – gas phase flowrate [m3/h]. The efficiency of biodegradation process was assessed by calculating specific elimination capacity (purification efficiency) EC defined as: (3)EC = (Cgin – Cgout)/ tg [g/(m3h)] and VOC conversion factor defined as: (4)K = [(Cgin – Cgout)/ Cgin]·100% where Cg out – VOC concentration at bioreactor outlet [g/m3]. After completing CTBB tests in the laboratory, the bioreactor was moved to the industrial site and connected with the ventilation system of the painting shop. Additional tests were carried out of VOCs biodegradation at air flowrates between 1.0 and 10.0 m3/h, and variable inlet concentration of pollutant resulting from the operations performed in the painting shop. Apart from measuring process parameters and evaluating biodegradation efficiency, pilot studies conducted in industrial conditions allowed verifying the importance of such factors as, the rate of changes in air flowrate and the concentration of pollutant, biofilm growth on the elements of bed packing, and the risk of process inhibition due to presence of toxic impurities in the air drawn from the ventilation system. 2.3. Testing full-scale CTBB in industry The full-scale industrial system for VOC biodegradation included the CTBB with a diameter of 2.8 m and a total height of 7.7 m. The photos of CTBB taken during the delivery of its components, as well as assembly and commissioning of the biodegradation system, are shown in Fig. 3. Fig. 3 Download : Download high-res image (1MB)Download : Download full-size image Fig. 3. Stages of delivery, assembly, and commissioning of CTBB at the industrial site. The working CTBB and control panel of its automation system are shown in Fig. 4. Tests of the biodegradation of VOC mixture were carried out continuously for several months, at gas and liquid phase flow rates Vg = 300–6000 m3/h and Vc = 10–100 m3/h, respectively, and VOC concentration in the gas phase at CTBB inlet Cg in = 5–1800 ppm. Fig. 4 Download : Download high-res image (515KB)Download : Download full-size image Fig. 4. CTBB and its control panel during the tests of bio-purification of air. 2.4. Analytical methods Before CTBB testing, it was necessary to develop appropriate measurement methods for the investigation of microflora growth, as well as possible growth inhibition effects, in microflora samples exposed to air at variable VOCs concentration. To determine the concentration of microbial cells in the suspension by absorbance measurement, a wavelength of 350 nm was selected. During CTBB tests, this made it possible to monitor the concentration of microorganisms in the circulating liquid phase by spectrophotometric measurement using Hach Lange DR 2800 from Mettler-Toledo; in addition, turbidity monitoring was performed using optical sensor JUMO ecoLine NTU (JUMO, Germany). The appearance of microorganisms was also evaluated by optical microscopy. As a complement to the quantitative analysis of microflora, the qualitative analysis of biological material was periodically carried out using the commercial identification kit NEFERMtest (http://www.erbalachema.com). Measurements of the content of VOCs and other components of the gas phase at the bioreactor inlet and outlet were performed using PID and FID detection equipment. During CTBB tests in full scale, VOC concentration measurements for the determination of VOC conversion factor were carried out in parallel by portable analyzer units Mudliar et al. (2010) model PGM-7600, MiniRAE 3000, and MultiRAE with PID detector from Honeywell. Periodic FID-based measurements were carried out using portable analyzers AWE-PW and AWE-PW2 (LAT, Poland). For safety reasons, the lower explosive limit and the concentration of carbon monoxide in the gas phase were also monitored. 3. Results and discussion 3.1. Selection of microorganisms and adaptation to target pollutant The isolation procedure mentioned in section 2.1 above was applied to a mixture of microorganisms coming from three sources: - collected soil samples, - bacterial cultures selected from the collection of microorganisms owned by Ekoinwentyka Ltd, - bacterial cultures purchased from a publicly available collection of microorganisms; these cultures included Pseudomonas fluorescens whose suitability for degrading the VOCs was investigated by some members of the author team in their previous research (Bak et al., 2017). In creating the conditions to favour the growth of microorganisms capable of degrading the VOCs, the target pollutants were simulated by a mixture of dichloromethane and formic acid in concentrations gradually increasing from 1 to 100 mg/dm3. Later, during the four-week adaptation period, several dozens of microorganism cultures that passed the simulation stage were exposed to air polluted by the VOCs actually present in the vapors generated from solvent formulations used in an industrial painting shop. After completing the procedure, 17 different cultures of bacterial consortia dominated by Pseudomonas fluorescens were found suitable for application in the industrial systems for VOC biodegradation. 3.2. CTBB tests in pilot scale In the pilot-scale tests, while aiming at the determination of rational ranges of parameters of the biodegradation process to ensure a high VOC conversion factor, much attention was also paid to the chemical composition of the liquid phase circulated in the system to ensure the supply of micronutrients needed for the growth of microorganisms in the bioreactor bed. The monitoring of pollutant load in the wastewater collected from CTBB circuit (mainly water vapor condensing in the stack and carryover of microdroplets of the liquid phase, up to 2 m3 per month) indicated BOD5 values not higher than 150 g/m3. Considered as an indirect measure of biofilm growth on the packing elements, air pressure drop across the bioreactor bed was below 200 Pa. Fig. 5, Fig. 6 depict examples of results of VOC biodegradation measurements aimed at determining how the efficiency of biodegradation depends on the mass of pollutants entering the bioreactor bed. Performed in the laboratory at variable gas-phase flowrate and liquid phase flowrate in the range Vc = 1.2–1.4 m3/h, the measurements enabled to identify relationships between specific elimination capacity EC and specific pollutant load Ms. As shown in Fig. 5, at Vg = 2.5 m3/h and Ms below 4.0 g/(m3h), it was possible to maintain high EC values up to around 3.8 g/(m3h) and VOC conversion factor up to K = 72–91%; however, when specific pollutant load was increased to Ms = 4–6 g/(m3h), the elimination capacity tended to decrease and VOC conversion factor dropped below 65%. Fig. 5 Download : Download high-res image (224KB)Download : Download full-size image Fig. 5. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg = 2.5 m3/h; the dashed line represents physical limit (VOC conversion factor 100%). Fig. 6 Download : Download high-res image (245KB)Download : Download full-size image Fig. 6. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg = 5 m3/h; the dashed line represents physical limit (VOC conversion factor 100%). The results obtained for higher flowrates of the gas phase indicated improvements in pollutant elimination capacity. As can be seen in Fig. 6, at Vg = 5 m3/h and specific pollutant loads up to Ms = 4.2 g/(m3h), the highest values of elimination capacity increased linearly to around 5.9 g/(m3h) and VOC conversion factor K = 94–99% was maintained, indicating bioreactor operation in the diffusion limiting regime (DLR). According to Kennes et al. (2009), a linear increase of EC with increasing Ms is characteristic of DLR conditions (in this case, Ms < 4.20 g/(m3·h)) because the interface between the gas and biofilm is relatively small and pollutant degradation occurs in the biofilm. The CTBB could be operated at still higher pollutant loads because a further increase in the EC would take place until a stationary phase is reached. Indeed, CTBB operation at higher values of Ms = 4.20–8.72 g/(m3h) resulted in EC values in the range 5.9–8.0 g/(m3h), and K values 89–94%. After completing laboratory tests, the CTBB was moved to the industrial site and installed in a piping circuit that allowed connecting the bioreactor with different air streams from the ventilation system of the painting shop. Measurements of the composition and concentrations of VOCs in the air streams at bioreactor inlet and outlet, at flowrates between 1.0 and 10.0 m3/h, were carried out by the personnel of a testing organization accredited following PN-EN ISO/IEC 17025. The range of chemical compounds found in the VOCs mixture varied depending on the production tasks executed in the painting shop. Typical components were solvent naphtha (petroleum) light aromatic, ethanol, isobutyl acetate, n - Butyl-acetate, propylene glycol methyl ether acetate, styrene, methyl methacrylate, n-butyl acrylate copolymer, 4-Methyl-2-pentanone. Examples of results obtained from the industrial tests of VOCs biodegradation in two different air streams (denoted E1 and E2) drawn from the ventilation system are shown in Fig. 7, Fig. 8. As can be seen, at inlet concentrations of the pollutant up to 170 ppm, VOCs concentration in the purified air Cgout was maintained below 20 ppm. This value was well below the upper limit of 50 ppm set by the management of the industrial site, per the relevant environmental permit. Fig. 7 Download : Download high-res image (409KB)Download : Download full-size image Fig. 7. Results of industrial tests of VOCs biodegradation in pilot-scale CTBB, air stream E1. Fig. 8 Download : Download high-res image (414KB)Download : Download full-size image Fig. 8. Results of industrial tests of VOCs biodegradation in pilot-scale CTBB, air stream E2. 3.3. CTBB tests in full scale The full-scale CTBB was installed in an industrial site as an add-on component of the ventilation system of a painting shop. During the initial phase of operation of full-scale CTBB, the focus was on critically important immobilization of microorganisms and biofilm growth, and starting up of measurements of process parameters. To ensure the success of that phase, mild process conditions were kept by setting air flowrate at Vg = 500 m3/h and maintaining VOC concentration at bioreactor inlet in the range Cgin = 4.0–5.5 ppm. According to the measurements of inlet and outlet concentrations of the pollutant illustrated in Fig. 9, VOC conversion factor K = 99.9% was achieved throughout the initial phase. Fig. 9 Download : Download high-res image (337KB)Download : Download full-size image Fig. 9. VOC concentrations at bioreactor inlet and outlet, and VOC conversion factor determined during the initial phase of CTBB tests in full scale. Positive results of the initial phase of CTBB operation made it possible to allow air flowrate and pollutant concentration at the bioreactor inlet to fluctuate freely with changing parameters of the discharged stream of ventilation air. During the period of test operation, air flowrate varied in the range Vg = 300–6000 m3/h and the inlet concentration of the pollutant was changing between 5 ppm and 2000 ppm. At typical values of air flowrate between 4000 m3/h and 6000 m3/h, air pressure drop across bioreactor bed ranged between 150 Pa and 300 Pa. The results of measurements of pollutant concentrations performed during a representative time interval of 20 h, shown in Fig. 10, indicate considerable flexibility of the VOC biodegradation system. Despite the widely changing air flowrate and inlet concentration of VOCs, their concentration at the bioreactor outlet was maintained in the range of 0.1–55 ppm. At moderate values of inlet VOC concentration lower than, or just above 200 ppm, pollutant conversion factor not lower than 99% was achieved. Short-lived concentration peaks – above 1000 ppm, and sometimes as high as 1800 ppm – typically resulted in the reduction of the conversion factor to around 85%. However, each time VOC concentration was back at the moderate level, the conversion factor quickly returned to the range of 95–99%. Fig. 10 Download : Download high-res image (572KB)Download : Download full-size image Fig. 10. VOC concentrations at bioreactor inlet and outlet, and VOC conversion factor determined during a representative 20-h interval of CTBB tests in full scale. The tests of full-scale CTBB confirmed the optimal ranges of parameters of the biodegradation process, namely temperature 20–35 °C, and pH = 6.0–7.5. Regarding process safety, the concentration of carbon monoxide was found to vary between 0 and 40 ppm without detectable inhibitory effects. No explosion risk occurred as VOC concentration never exceeded 4% of LEL (lower explosive limit). 4. Discussion The experimental results presented in 1 Introduction, 2 Materials and methods, 3 Results and discussion.3 above can be compared with the results of research performed by other researchers on biodegradation of VOCs in biotrickling filters on a laboratory or pilot scale and summarized in the review paper by Rybarczyk et al. (2019). As long as moderate values below 200 ppm of pollutant concentration at bioreactor inlet were maintained during CTBB tests in both pilot and full scale, typical values of VOC conversion factor K = 95–99% obtained in the present research were comparable with the highest K values reported by other researchers. Moreover, while short-lived concentration peaks up to 1800 ppm were found to reduce the conversion factor to around 85%, its value quickly returned to the typical range as soon as VOC concentration was back at the moderate level. Apart from quantitative information acquired through measurements and processing of measurement data, important qualitative information was collected during the period of test operation of full-scale CTBB. As long as the values of process parameters were maintained within or close to their optimal r Shang et al., 2019 K. Shang, M. Wang, B. Peng, J. Li, N. Lu, N. Jiang, Y. Wu Characterization of a novel volume-surface DBD reactor: discharge characteristics, ozone production and benzene degradation J. Phys. D Appl. Phys., 53 (2019) 065201 Shareefdeen and Singh, 2005 Z. Shareefdeen, A. Singh (Eds.), Biotechnology for Odor and Air Pollution Control, Springer, Berlin Heidelberg, New York (2005) Speight, 2018 J.G. Speight Reaction Mechanisms in Environmental Engineering – Analysis and Prediction 978-0-12-804422-3, Elsevier/Butterworth-Heinemann (2018) Thakur et al., 2011 P.K. Thakur, M.A. Kumar, B. Chandrajit Biofiltration of volatile organic compounds (VOCs) – an overview Res. J. Chem. Sci., 1 (8) (2011), pp. 83-92 Webster et al., 1999 T.S. Webster, A.P. Togna, W.J. Guarini, L. McKnight Application of a biological trickling filter reactor to treat volatile organic compound emissions from a spray paint booth operation Met. Finish., 97 (3) (1999), pp. 24-26 Wu et al., 2018 H. Wu, H. Yan, Y. Quan, H. Zhao, N. Jiang, C. Yin Recent progress and perspectives in biotrickling filters for VOCs and odorous gases treatment J. Environ. Manag., 222 (2018), pp. 409-419 Wysocka et al., 2019 I. Wysocka, J. Gębicki, J. Namieśnik Technologies for deodorization of malodorous gases Environ. Sci. Pollut. Res., 26 (10) (2019), pp. 9409-9434 Yang et al., 2019 Z. Yang, J. Li, J. Liu, J. Cao, D. Sheng, T. Cai Evaluation of a pilot-scale bio-trickling filter as a VOCs control technology for the chemical fibre wastewater treatment plant J. Environ. Manag., 246 (2019), pp. 71-76 Yoshikawa et al., 2017 M. Yoshikawa, M. Zhang, K. Toyota Integrated anaerobic-aerobic biodegradation of multiple contaminants including chlorinated ethylenes, benzene, toluene, and dichloromethane Water Air Soil Pollut., 228 (1) (2017) article No. 25 Zhang et al., 2020 T. Zhang, G. Li, Y. Yu, Y. Ji, T. An Atmospheric diffusion profiles and health risks of typical VOC: numerical modelling study J. Clean. Prod., 275 (2020), Article 122982
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spelling	Kasperczyk, DamianUrbaniec, KrzysztofBarbusinski, KrzysztofRene, Eldon R.Colmenares Quintero, Ramón Fernando3092021-05-20T19:06:35Z2022-06-092021-05-20T19:06:35Z2021-05-0909596526https://doi.org/10.1016/j.jclepro.2021.127440https://hdl.handle.net/20.500.12494/34345Kasperczyk, D., Urbaniec, K., Barbusiński, K., Rene, E., & Colmenares-Quintero, R. (2021). Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry. Journal of Cleaner Production, 309, 127440–. https://doi.org/10.1016/j.jclepro.2021.127440La industria de la pintura de automóviles es una fuente de contaminación ambiental causada por los compuestos orgánicos volátiles (COV) presentes en el aire de ventilación descargado. Para contribuir a la mitigación de este tipo de contaminación atmosférica, Ekoinwentyka Ltd. desarrolló -desde la escala piloto hasta la escala completa- y adaptó la tecnología del biorreactor de lecho de goteo compacto (CTBB), cuyo principio de funcionamiento se basa en el flujo descendente de la fase gaseosa (aire contaminado) y la fase líquida (solución de sales minerales) a través de un lecho empacado en el que los microorganismos activos se inmovilizan en la biopelícula de las superficies de los elementos de empaquetado. El biorreactor a escala piloto de 0,32 m de diámetro y 1,50 m de altura total tenía su lecho empacado inoculado con un consorcio de microorganismos dominado por la bacteria Pseudomonas fluorescens. Durante el programa experimental, que duró varios meses, el caudal de aire extraído del sistema de ventilación del taller de pintura variaba entre 1,0 y 10,0 m3/h y la concentración de entrada de COV oscilaba entre 10 y 200 ppm. Al medir la concentración de COV en el aire purificado, se comprobó que el factor de biodegradación de los COV oscilaba entre el 85 y el 99%. A partir de los experimentos a escala piloto, se ha desarrollado un CTBB a escala real de 2,8 m de diámetro y 10 m de altura total y se ha instalado como componente adicional del sistema de ventilación del taller de pintura. Las pruebas realizadas con caudales de gas de hasta 6.000 m3/h confirmaron un factor de biodegradación de COV del 85-99%, lo que demuestra un resultado positivo de la adaptación de la tecnología CTBB a las condiciones de la industria de la pintura de automóviles.The automotive painting industry is a source of environmental pollution caused by Volatile Organic Compounds (VOCs) present in the discharged ventilation air. To contribute to the mitigation of this type of air pollution, Ekoinwentyka Ltd. developed – from pilot scale to full scale – and adapted the technology of Compact Trickle Bed Bioreactor (CTBB) whose operating principle builds upon co-current downflow of the gas phase (polluted air) and liquid phase (solution of mineral salts) through a packed bed where active microorganisms are immobilized in the biofilm on the surfaces of packing elements. Pilot-scale bioreactor 0.32 m in diameter and 1.50 m total height had its packed bed inoculated with a consortium of microorganisms dominated by Pseudomonas fluorescens bacteria. During the experimental programme that lasted several months, the flow rate of air drawn from the ventilation system of the painting shop was changing between 1.0 and 10.0 m3/h and the inlet concentration of VOCs ranged from 10 to 200 ppm. By measuring VOC concentration in the purified air, the factor of VOC biodegradation was found to range between 85 and 99%. Based on pilot-scale experiments, full-scale CTBB has been developed 2.8 m in diameter and 10 m total height and installed as an add-on component of the ventilation system of the painting shop. Test operation at gas flow rates up to 6000 m3/h, confirmed VOC biodegradation factor at the level of 85–99% thus proving a positive result of CTBB technology adaptation to the conditions of the automotive painting industry.https://scienti.colciencias.gov.co/cvlac/visualizador/generarCurriculoCv.do?cod_rh=0000192503https://orcid.org/0000-0001-8240-6650https://orcid.org/0000-0001-5974-2808https://orcid.org/0000-0003-1166-1982https://scienti.minciencias.gov.co/gruplac/jsp/visualiza/visualizagr.jsp?nro=00000000005961biuro@ekoinwentyka.plkrzysztof.urbaniec@pw.edu.plkrzysztof.barbusinski@polsl.ple.raj@un-ihe.orgramon.colmenaresq@campusucc.edu.cohttps://scholar.google.com/citations?user=9HLAZYUAAAAJ&hl=es1-10 p.Universidad Cooperativa de Colombia, Facultad de Ingenierías, Ingeniería Civil, Medellín y EnvigadoIngeniería CivilMedellínhttps://bbibliograficas.ucc.edu.co:2152/science/article/pii/S0959652621016590?via%3DihubJournal of Cleaner ProductionÁlvarez-Hornos et al., 2011 F.J. Álvarez-Hornos, C. Lafita, V. Martínez-Soria, J.M. Penya-Roja, M.C. Pérez, C. Gabaldón Evaluation of a pilot-scale biotrickling filter as a VOC control technology for the plastic coating sector Biochem. Eng. J., 58–59 (2011), pp. 154-161Bak et al., 2017 A. Bak, V. Kozik, P. Dybal, S. Sułowicz, D. Kasperczyk, S. Kus, K. Barbusinski Abatement robustness of volatile organic compounds using compact trickle-bed bioreactor: biotreatment of styrene, ethanol and dimethyl sulfide mixture in contaminated airstream Int. Biodeterior. Biodegrad., 119 (2017), pp. 316-328Barbusinski et al., 2017 K. Barbusinski, K. Kalemba, D. Kasperczyk, K. Urbaniec, V. Kozik Biological methods for odor treatment - a review J. Clean. Prod., 152 (2017), pp. 223-241Brancher et al., 2017 M. Brancher, K.D. Griffiths, D. Franco, H. de Melo Lisboa A review of odour impact criteria in selected countries around the world Chemosphere, 168 (2017), pp. 1531-1570Brinkmann et al., 2016 T. Brinkmann, G. Giner Santonja, H. Yükseler, S. Roudier, L. Delgado Sancho Best available techniques (BAT) reference document for common waste water and waste gas treatment/management systems in the chemical sector Available at https://eippcb.jrc.ec.europa.eu/reference (2016)Cox and Deshusses, 2001 H.H.J. Cox, M.A. Deshusses Biotrickling filters C. Kennes, M.C. Veiga (Eds.), Bioreactors for Waste Gas Treatment, Kluwer, Dordrecht (2001), pp. 133-162Cui et al., 2020 P. Cui, G. Schito, Q. Cui VOC emissions from asphalt pavement and health risks to construction workers J. Clean. Prod., 244 (2020), p. 118757Delvigne and Lecomte, 2010 F. Delvigne, J. Lecomte Foam formation and control in bioreactors M.C. Flickinger (Ed.), Encyclopedia of Industrial Biotechnology: Bioprocess, Bioseparation, and Cell Technology, Wiley (2010)Diks and Ottengraf, 1991 R.M.M. Diks, S.P.P. Ottengraf Verification studies of a simplified model for the removal of dichloromethane from waste gases using a biological trickling filter Bioprocess Eng. Part I, 6 (1991), pp. 93-99 Part II vol. 6, 131-140Gąszczak et al., 2018 A. Gąszczak, G. Bartelmus, A. Rotkegel, R. Sarzynski Experiments and modelling of a biotrickling filter (BTF) for removal of styrene from airstreams J. Chem. Technol. Biotechnol., 93 (9) (2018), pp. 2659-2670Gospodarek et al., 2019 M. Gospodarek, P. Rybarczyk, B. Szulczynski, J. Gębicki Comparative evaluation of selected biological methods for the removal of hydrophilic and hydrophobic odorous VOCs from air Processes, 7 (2019), p. 187Kasperczyk and Urbaniec, 2015 D. Kasperczyk, K. Urbaniec Application of a compact trickle-bed bioreactor to the biodegradation of pollutants from the ventillation air in a copper-ore mine J. Clean. Prod., 87 (2015), pp. 971-976Kasperczyk et al., 2019 D. Kasperczyk, K. Urbaniec, K. Barbusiński, E.R. Rene, R.F. Colmenares-Quintero Application of a compact trickle-bed bioreactor for the removal of odor and volatile organic compounds emitted from a wastewater treatment plant J. Environ. Manag., 236 (2019), pp. 413-419Kasperczyk et al., 2019 D. Kasperczyk, K. Urbaniec, K. Barbusiński, E.R. Rene, R.F. Colmenares-Quintero Application of a compact trickle-bed bioreactor for the removal of odor and volatile organic compounds emitted from a wastewater treatment plant J. Environ. Manag., 236 (2019), pp. 413-419Kennes et al., 2009 C. Kennes, M. Montes, M.E. López, M.C. Veiga Waste gas treatment in bioreactors: environmental engineering aspects Can. J. Civ. Eng., 36 (2009), pp. 1887-1894Kennes and Thalasso, 1998 C. Kennes, F. Thalasso Waste gas biotreatment technology J. Chem. Technol. Biotechnol., 72 (1998), pp. 303-319Kirchner et al., 1996 K. Kirchner, S. Wagner, H.-J. Rehm Removal of organic air pollutants from exhaust gases in the trickle-bed bioreactor. Effect of oxygen Appl. Microbiol. Biotechnol., 45 (1996), pp. 415-419Lafita et al., 2012 C. Lafita, J.‐M. Penya‐Roja, C. Gabaldón, V. Martínez‐Soria Full‐scale biotrickling filtration of volatile organic compounds from air emission in wood‐coating activities J. Chem. Technol. Biotechnol., 87 (2012), pp. 732-738Liao et al., 2018 D. Liao, E. Li, J. Li, P. Zeng, R. Feng, M. Xu, G. Sun Removal of benzene, toluene, xylene and styrene by biotrickling filters and identification of their interactions PloS One, 13 (2018), Article e0189927Mudliar et al., 2010 S. Mudliar, B. Giri, K. Padoley, D. Satpute, R. Dixit, P. Bhatt, R. Pandey, A. Juwarkar, A. Vaidya Bioreactors for treatment of VOCs and odours – a review J. Environ. Manag., 91 (2010), pp. 1039-1054Oyarzun et al., 2019 P. Oyarzun, L. Alarcón, G. Calabriano, J. Bejarano, D. Nuñez, N. Ruiz-Taglec, H. Urrutia Trickling filter technology for biotreatment of nitrogenous compounds emitted in exhaust gases from fishmeal plants J. Environ. Manag., 232 (2019), pp. 165-170Rybarczyk et al., 2019 P. Rybarczyk, B. Szulczyński, J. Gębicki, J. Hupka Treatment of malodorous air in biotrickling filters: a review Biochem. Eng. J., 141 (2019), pp. 146-162Salamanca et al., 2017 D. Salamanca, D. Dobslaw, K.H. Engesser Removal of cyclohexane gaseous emissions using a biotrickling filter system Chemosphere, 176 (2017), pp. 97-107San-Valero et al., 2018 P. San-Valero, A.D. Dorado, V. Martínez-Soria, C. Gabaldón Biotrickling filter modeling for styrene abatement. Part 1: model development, calibration and validation on an industrial scale Chemosphere, 191 (2018), pp. 1066-1074San-Valero et al., 2019 P. San-Valero, C. Gabaldón, F.J. Álvarez-Hornos, M. Izquierdo, V. Martínez-Soria Removal of acetone from air emissions by biotrickling filters: providing solutions from laboratory to full-scale J. Environ. Sci. Health A Tox Hazard Subst. Environ. Eng., 54 (1) (2019), pp. 1-8Search ScienceDirect Outline Abstract Keywords 1. Introduction 2. Materials and methods 3. Results and discussion 4. Discussion 5. Conclusions CRediT authorship contribution statement Declaration of competing interest Acknowledgements References Figures (10) Fig. 1. Simplified scheme of the laboratory setup for CTBB tests: 1) Blower 2) Valves,… Fig. 2. Photograph of the laboratory setup Fig. 3. Stages of delivery, assembly, and commissioning of CTBB at the industrial site Fig. 4. CTBB and its control panel during the tests of bio-purification of air Fig. 5. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg=2 Fig. 6. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg=5m3/h;… Elsevier Journal of Cleaner Production Volume 309, 1 August 2021, 127440 Journal of Cleaner Production Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry Author links open overlay panelDamianKasperczykaKrzysztofUrbaniecbKrzysztofBarbusińskicEldon R.RenedRamon F.Colmenares-Quinteroe https://doi.org/10.1016/j.jclepro.2021.127440Get rights and content Abstract The automotive painting industry is a source of environmental pollution caused by Volatile Organic Compounds (VOCs) present in the discharged ventilation air. To contribute to the mitigation of this type of air pollution, Ekoinwentyka Ltd. developed – from pilot scale to full scale – and adapted the technology of Compact Trickle Bed Bioreactor (CTBB) whose operating principle builds upon co-current downflow of the gas phase (polluted air) and liquid phase (solution of mineral salts) through a packed bed where active microorganisms are immobilized in the biofilm on the surfaces of packing elements. Pilot-scale bioreactor 0.32 m in diameter and 1.50 m total height had its packed bed inoculated with a consortium of microorganisms dominated by Pseudomonas fluorescens bacteria. During the experimental programme that lasted several months, the flow rate of air drawn from the ventilation system of the painting shop was changing between 1.0 and 10.0 m3/h and the inlet concentration of VOCs ranged from 10 to 200 ppm. By measuring VOC concentration in the purified air, the factor of VOC biodegradation was found to range between 85 and 99%. Based on pilot-scale experiments, full-scale CTBB has been developed 2.8 m in diameter and 10 m total height and installed as an add-on component of the ventilation system of the painting shop. Test operation at gas flow rates up to 6000 m3/h, confirmed VOC biodegradation factor at the level of 85–99% thus proving a positive result of CTBB technology adaptation to the conditions of the automotive painting industry. Previous article in issueNext article in issue Keywords Volatile organic compoundCompact trickle bed bioreactorIndustrial painting shopVentilation systemPollutant biodegradation 1. Introduction Volatile Organic Compounds (VOC's) constitute one of the most important groups of pollutants that are emitted from industrial activities to the atmosphere (Cui et al., 2020) and may pose a great exposure risk to surrounding residents (Zhang et al., 2020). Apart from being odorous and toxic, these substances as precursors of photochemical oxidation are responsible for the formation of tropospheric ozone and the occurrence of smog (Speight, 2018). To avoid violation of emission standards (Brancher et al., 2017), it may be necessary to remove VOC's from industrial waste gases (Brinkmann et al., 2016). Various chemical and physical techniques of gas cleaning are available for the elimination of organic and other odorous compounds from waste gas streams (Wysocka et al., 2019). A broad spectrum of compounds can be removed using chemical methods, however, they are energy intensive and/or necessitate the use of chemicals. If waste gases are treated by physical methods, then pollutants are shifted to solid or liquid sorbents, and the subsequent regeneration of these results often in the creation of a new pollutant. As a more sustainable alternative, energy efficient and environment friendly biological techniques employing indigenous bacteria can be applied for the removal of VOCs from waste gases as indicated by Kennes and Thalasso (1998), and extensively discussed in the book edited by Shareefdeen and Singh (2005). Reflecting the progress in research and the accumulation of industrial experience, the application potential of biological VOC removal was later evaluated by Thakur et al. (2011) and more recently, discussed by Barbusinski et al. (2017). As another option of environment friendly waste gas cleaning, VOC oxidation by discharge plasma may also be mentioned (Shang et al., 2019) but this is an emerging technology not yet ripe for industrial application. Odors and VOCs removal in simple biofilters with soil beds dates back to the 1950ties. At the turn of the 20th century, the application of more sophisticated biotrickling filters (BFs) was studied theoretically and experimentally (Diks and Ottengraf, 1991), and introduced to industries (Kirchner et al., 1996), including metal painting shops (Webster et al., 1999) where the cleaning of waste gases is a necessity. The advantages of BF technology for the biodegradation of VOCs were recognized (Cox and Deshusses, 2001) making for a continuation of this line of research (Álvarez-Hornos et al., 2011) and BF applications in the wood finishing and painting industry (Lafita et al., 2012). It is now widely understood that VOCs removal can be performed in biofilters, bioscubbers, and biotrickling filters. A specific equipment type is usually selected depending on its range of economic application (Mudliar et al., 2010) but when the application requires operational flexibility of the equipment, biotrickling filters – also known as trickle-bed-bioreactors – are preferred providing also the advantage of compactness and moderate cost (Rybarczyk et al., 2019). However, as pointed out by Oyarzun et al. (2019), biotrickling filtration still is considered an innovative technology, and its transfer to new application areas is rather slow. In recent years, using laboratory or pilot scale BFs, researchers investigated biodegradation of individual VOC species including cyclohexane (Salamanca et al., 2017) and 1-butanol (Schmidt and Anderson, 2017), or VOCs mixtures exemplified by ones containing benzene, toluene, xylene, and styrene (Liao et al., 2018), and by waste gases from chemical fibre wastewater treatment plant (Yang et al., 2019). Full-scale application of BF technology for VOC biodegradation in the wood finishing and painting industry was reported by e.g., San Valero et al. (2019). The key component of a BF is its filter bed made of some synthetic or natural inert material on which active microorganisms are immobilized forming a biofilm. An aqueous phase (mineral salt solution) is trickled over the filter bed, while the gas phase to be cleaned flows in co- or counter-current through the bed. The pollutants to be removed are initially dissolved in the aqueous film that covers the biofilm and then diffused into the biofilm where biodegradation occurs (Kasperczyk et al., 2019). Given the above characteristics of BF operation, hydrophilicity or hydrophobicity of the pollutants should be accounted for in the selection of equipment for VOCs treatment (Gospodarek et al., 2019). As pointed out by Wu et al. (2018), the VOCs and odorants removal performance by BF may be limited by the hydrophobicity, toxicity, and low bioavailability of these pollutants. Therefore, the issues of selection and adaptation of microorganisms to the degraded pollutants are particularly important for this type of process. Understanding and modeling of the phenomena occurring in the BFs, as well as a detailed analysis of the biodegradation process, constitute the basis for their design, optimization, and maintenance of the BFs, as can be seen in a study on styrene removal from airstreams published by Gąszczak et al. (2018). A similar approach was adopted by San-Valero et al. (2018) in their investigations of styrene abatement. The present authors have previously investigated applications of a specific BF design to the elimination of hydrogen sulphide, and other odorous compounds from the streams of waste air discharged from a deep copper-ore mine (Kasperczyk and Urbaniec, 2015) and wastewater treatment plant (Kasperczyk et al., 2019). The bioreactor, developed by Ekoinwentyka Ltd, is known as the compact trickle-bed bioreactor (CTBB). In the present work, the attention is turned to CTBB application for the removal of VOCs, such as solvent vapors, emitted from the automotive painting industry. The aim of the research was twofold: - Firstly, to isolate microorganisms suitable for VOC removal and to test a pilot scale CTBB, inoculated with these microorganisms. The bioreactor was initially installed and tested in the company's laboratory and later moved to an industrial site where the tests were continued. By performing pilot-scale tests in the industrial plant, the efficiency of the microorganisms in degrading the VOCs was ascertained. - Secondly, based on the experience from the pilot scale, to develop and apply a full scale CTBB for the removal of VOCs from the ventilation air discharged from an industrial painting shop. Measurements and observations were made to evaluate the performance of CTBB, including the efficiency of VOC degradation, under industrial conditions where disturbances in process parameters may occur. Positive results of VOCs removal in the full-scale CTBB in the automotive painting shop constitute the main novelty of the present work. Upon the completion of bioreactor tests, the CTBB was put into commercial operation of the shop's ventilation system. 2. Materials and methods 2.1. Selection of microorganisms for VOC removal The process concept assumes the use of microorganisms naturally occurring at the place where pollutants are present. To achieve that, it is necessary to develop and apply procedures for isolation and selection of suitable bacterial strains followed by their adaptation to the target pollutants, and to optimize the conditions for the growth of bacterial flora. Potentially useful microorganisms are initially secured by collecting soil samples from industrial sites where automotive painting shops are in operation. In the next stage, a bacterial consortium capable of degrading VOCs is isolated using the enrichment culture technique. It requires supplying nutrients and creating environmental conditions for the growth of microorganism mixture so controlled as to favour the growth of bacterial strains that degrade the VOCs efficiently. Following the formation of a suitable microbial consortium, the final stage of the procedure is executed by exposing the consortium to the target pollutants at real-life concentration levels. The adaptation to the application conditions is completed when stable growth of the microorganisms has been observed during that stage. 2.2. Testing Compact Trickle Bed Bioreactor in pilot scale The pilot-scale tests were aimed to determine the optimal parameters of VOC biodegradation conducted in CTBB to achieve high efficiency of the process, as well as to acquire information needed for creating a data map that would allow upscaling this technology and implementing it in selected industrial painting shops. After inoculating the bioreactor bed with the selected microorganisms and securing biofilm formation on the bed packing, the pilot CTBB was ready for testing biodegradation of VOCs present in the air stream supplied to the bioreactor inlet. The set of relevant process parameters included, gas and liquid phase flowrates, VOCs concentrations in the gas stream at bioreactor inlet and outlet, gas residence time (dependent on the characteristics of bed packing), oxygen content in the mineral salt solution, temperature, pH, and physiological parameters of biomass formation in bioreactor bed. Apart from measuring these parameters, pilot studies conducted in the laboratory enabled verifying the choice of packing elements and estimating the relationship between the efficiency of VOCs biodegradation and changing process conditions. The scheme of laboratory setup in which the process of cleaning the air from volatile impurities was conducted is shown in Fig. 1. Its main component is the Compact Trickle Bed Bioreactor made of stainless steel with a diameter of 0.315 m and active bed 0.6 m high, packed with polypropylene Ralu Rings sized 15 × 15 mm. The gas phase in the tests was air pumped by a compressor (1). After passing through the filter system (4), the air was heated to about 25 °C (during test operation, the system was carefully thermostated) and supplied to the bioreactor. The solution of VOCs used in the industrial process of varnishing/painting was dosed by a micro-pump connected to a column packed with glass particles, where the VOCs evaporated to the main air stream. Pollutant concentration in the supplied gas was determined near the bioreactor inlet. The liquid phase circulating in the system was a solution of mineral salts (total volume around 25 L) whose parameters, including flowrate, pH, temperature, and absorbance (indicating the concentration of microorganisms in the solution) were controlled, and regulated on-line using auxiliary equipment such as micro-pumps dispensing buffer solutions, control valves and heaters. The liquid distributor (13) placed above the bioreactor bed ensured that gas and liquid flowing co-currently downwards were brought into contact over the packing surface. The concentration of pollutant remaining in the purified gas was determined after the discharged gas passed the droplet separator. Fig. 1 Download : Download high-res image (480KB)Download : Download full-size image Fig. 1. Simplified scheme of the laboratory setup for CTBB tests: 1) Blower 2) Valves, 3) Gas-phase control system 4) Pre-filter, 5) Gas flow meter, 6) Liquid source, 7) Droplet separator, 8) Liquid tank in bioreactor base, 9) Liquid level meter, 10) Inverter-controlled pump, 11) Liquid flow meter, 12) Pumps dispensing buffer solutions to maintain the required living environment for microorganisms, 13) Liquid distributor, 14) Pump, 15) Level-control valves, 16) Measurements of process-relevant parameters in the gas and liquid phases, G – bed support grate, S – sight glass, ---- liquid phase, --- gas phase. A photo of the laboratory setup including its control equipment is shown in Fig. 2. Before starting the process, to minimize the presence of microorganisms other than the selected ones, the entire setup was sterilized by rinsing three times with alcohol solution and irradiated for several hours using a UV lamp. This was followed by the immobilization of microorganisms on the packing of the bioreactor bed. To this end, microorganisms adapted to VOC degradation (mainly Pseudomonas fluorescens; more information is given in Section 3.1) were mixed with 10 L of the liquid phase, and the resulting suspension was circulated through the bed for around 3 days until changes in the absorbance of suspension occurred thus indicating the formation of biofilm layer on the packing. After that, the suspension was removed from the setup, the bed was rinsed with sterile mineral-salt solution, and the process was started by setting gas and liquid flowrates, and pollutant concentration in the gas supplied to the bioreactor. Fig. 2 Download : Download high-res image (514KB)Download : Download full-size image Fig. 2. Photograph of the laboratory setup. The VOC biodegradation setup was continuously operated in the laboratory for several months. By varying the flowrates of gas and liquid phases, different values were set of specific pollutant load Ms defined as: (1)Ms = Cgin / tg [g/(m3h)] where: Cgin – VOC concentration at bioreactor inlet [g/m3], and tg – average gas residence time: (2)tg = Vbed / Vg [h] where Vbed – empty bed volume [m3] and Vg – gas phase flowrate [m3/h]. The efficiency of biodegradation process was assessed by calculating specific elimination capacity (purification efficiency) EC defined as: (3)EC = (Cgin – Cgout)/ tg [g/(m3h)] and VOC conversion factor defined as: (4)K = [(Cgin – Cgout)/ Cgin]·100% where Cg out – VOC concentration at bioreactor outlet [g/m3]. After completing CTBB tests in the laboratory, the bioreactor was moved to the industrial site and connected with the ventilation system of the painting shop. Additional tests were carried out of VOCs biodegradation at air flowrates between 1.0 and 10.0 m3/h, and variable inlet concentration of pollutant resulting from the operations performed in the painting shop. Apart from measuring process parameters and evaluating biodegradation efficiency, pilot studies conducted in industrial conditions allowed verifying the importance of such factors as, the rate of changes in air flowrate and the concentration of pollutant, biofilm growth on the elements of bed packing, and the risk of process inhibition due to presence of toxic impurities in the air drawn from the ventilation system. 2.3. Testing full-scale CTBB in industry The full-scale industrial system for VOC biodegradation included the CTBB with a diameter of 2.8 m and a total height of 7.7 m. The photos of CTBB taken during the delivery of its components, as well as assembly and commissioning of the biodegradation system, are shown in Fig. 3. Fig. 3 Download : Download high-res image (1MB)Download : Download full-size image Fig. 3. Stages of delivery, assembly, and commissioning of CTBB at the industrial site. The working CTBB and control panel of its automation system are shown in Fig. 4. Tests of the biodegradation of VOC mixture were carried out continuously for several months, at gas and liquid phase flow rates Vg = 300–6000 m3/h and Vc = 10–100 m3/h, respectively, and VOC concentration in the gas phase at CTBB inlet Cg in = 5–1800 ppm. Fig. 4 Download : Download high-res image (515KB)Download : Download full-size image Fig. 4. CTBB and its control panel during the tests of bio-purification of air. 2.4. Analytical methods Before CTBB testing, it was necessary to develop appropriate measurement methods for the investigation of microflora growth, as well as possible growth inhibition effects, in microflora samples exposed to air at variable VOCs concentration. To determine the concentration of microbial cells in the suspension by absorbance measurement, a wavelength of 350 nm was selected. During CTBB tests, this made it possible to monitor the concentration of microorganisms in the circulating liquid phase by spectrophotometric measurement using Hach Lange DR 2800 from Mettler-Toledo; in addition, turbidity monitoring was performed using optical sensor JUMO ecoLine NTU (JUMO, Germany). The appearance of microorganisms was also evaluated by optical microscopy. As a complement to the quantitative analysis of microflora, the qualitative analysis of biological material was periodically carried out using the commercial identification kit NEFERMtest (http://www.erbalachema.com). Measurements of the content of VOCs and other components of the gas phase at the bioreactor inlet and outlet were performed using PID and FID detection equipment. During CTBB tests in full scale, VOC concentration measurements for the determination of VOC conversion factor were carried out in parallel by portable analyzer units Mudliar et al. (2010) model PGM-7600, MiniRAE 3000, and MultiRAE with PID detector from Honeywell. Periodic FID-based measurements were carried out using portable analyzers AWE-PW and AWE-PW2 (LAT, Poland). For safety reasons, the lower explosive limit and the concentration of carbon monoxide in the gas phase were also monitored. 3. Results and discussion 3.1. Selection of microorganisms and adaptation to target pollutant The isolation procedure mentioned in section 2.1 above was applied to a mixture of microorganisms coming from three sources: - collected soil samples, - bacterial cultures selected from the collection of microorganisms owned by Ekoinwentyka Ltd, - bacterial cultures purchased from a publicly available collection of microorganisms; these cultures included Pseudomonas fluorescens whose suitability for degrading the VOCs was investigated by some members of the author team in their previous research (Bak et al., 2017). In creating the conditions to favour the growth of microorganisms capable of degrading the VOCs, the target pollutants were simulated by a mixture of dichloromethane and formic acid in concentrations gradually increasing from 1 to 100 mg/dm3. Later, during the four-week adaptation period, several dozens of microorganism cultures that passed the simulation stage were exposed to air polluted by the VOCs actually present in the vapors generated from solvent formulations used in an industrial painting shop. After completing the procedure, 17 different cultures of bacterial consortia dominated by Pseudomonas fluorescens were found suitable for application in the industrial systems for VOC biodegradation. 3.2. CTBB tests in pilot scale In the pilot-scale tests, while aiming at the determination of rational ranges of parameters of the biodegradation process to ensure a high VOC conversion factor, much attention was also paid to the chemical composition of the liquid phase circulated in the system to ensure the supply of micronutrients needed for the growth of microorganisms in the bioreactor bed. The monitoring of pollutant load in the wastewater collected from CTBB circuit (mainly water vapor condensing in the stack and carryover of microdroplets of the liquid phase, up to 2 m3 per month) indicated BOD5 values not higher than 150 g/m3. Considered as an indirect measure of biofilm growth on the packing elements, air pressure drop across the bioreactor bed was below 200 Pa. Fig. 5, Fig. 6 depict examples of results of VOC biodegradation measurements aimed at determining how the efficiency of biodegradation depends on the mass of pollutants entering the bioreactor bed. Performed in the laboratory at variable gas-phase flowrate and liquid phase flowrate in the range Vc = 1.2–1.4 m3/h, the measurements enabled to identify relationships between specific elimination capacity EC and specific pollutant load Ms. As shown in Fig. 5, at Vg = 2.5 m3/h and Ms below 4.0 g/(m3h), it was possible to maintain high EC values up to around 3.8 g/(m3h) and VOC conversion factor up to K = 72–91%; however, when specific pollutant load was increased to Ms = 4–6 g/(m3h), the elimination capacity tended to decrease and VOC conversion factor dropped below 65%. Fig. 5 Download : Download high-res image (224KB)Download : Download full-size image Fig. 5. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg = 2.5 m3/h; the dashed line represents physical limit (VOC conversion factor 100%). Fig. 6 Download : Download high-res image (245KB)Download : Download full-size image Fig. 6. Elimination capacity of VOCs biodegradation in pilot-scale CTBB at Vg = 5 m3/h; the dashed line represents physical limit (VOC conversion factor 100%). The results obtained for higher flowrates of the gas phase indicated improvements in pollutant elimination capacity. As can be seen in Fig. 6, at Vg = 5 m3/h and specific pollutant loads up to Ms = 4.2 g/(m3h), the highest values of elimination capacity increased linearly to around 5.9 g/(m3h) and VOC conversion factor K = 94–99% was maintained, indicating bioreactor operation in the diffusion limiting regime (DLR). According to Kennes et al. (2009), a linear increase of EC with increasing Ms is characteristic of DLR conditions (in this case, Ms < 4.20 g/(m3·h)) because the interface between the gas and biofilm is relatively small and pollutant degradation occurs in the biofilm. The CTBB could be operated at still higher pollutant loads because a further increase in the EC would take place until a stationary phase is reached. Indeed, CTBB operation at higher values of Ms = 4.20–8.72 g/(m3h) resulted in EC values in the range 5.9–8.0 g/(m3h), and K values 89–94%. After completing laboratory tests, the CTBB was moved to the industrial site and installed in a piping circuit that allowed connecting the bioreactor with different air streams from the ventilation system of the painting shop. Measurements of the composition and concentrations of VOCs in the air streams at bioreactor inlet and outlet, at flowrates between 1.0 and 10.0 m3/h, were carried out by the personnel of a testing organization accredited following PN-EN ISO/IEC 17025. The range of chemical compounds found in the VOCs mixture varied depending on the production tasks executed in the painting shop. Typical components were solvent naphtha (petroleum) light aromatic, ethanol, isobutyl acetate, n - Butyl-acetate, propylene glycol methyl ether acetate, styrene, methyl methacrylate, n-butyl acrylate copolymer, 4-Methyl-2-pentanone. Examples of results obtained from the industrial tests of VOCs biodegradation in two different air streams (denoted E1 and E2) drawn from the ventilation system are shown in Fig. 7, Fig. 8. As can be seen, at inlet concentrations of the pollutant up to 170 ppm, VOCs concentration in the purified air Cgout was maintained below 20 ppm. This value was well below the upper limit of 50 ppm set by the management of the industrial site, per the relevant environmental permit. Fig. 7 Download : Download high-res image (409KB)Download : Download full-size image Fig. 7. Results of industrial tests of VOCs biodegradation in pilot-scale CTBB, air stream E1. Fig. 8 Download : Download high-res image (414KB)Download : Download full-size image Fig. 8. Results of industrial tests of VOCs biodegradation in pilot-scale CTBB, air stream E2. 3.3. CTBB tests in full scale The full-scale CTBB was installed in an industrial site as an add-on component of the ventilation system of a painting shop. During the initial phase of operation of full-scale CTBB, the focus was on critically important immobilization of microorganisms and biofilm growth, and starting up of measurements of process parameters. To ensure the success of that phase, mild process conditions were kept by setting air flowrate at Vg = 500 m3/h and maintaining VOC concentration at bioreactor inlet in the range Cgin = 4.0–5.5 ppm. According to the measurements of inlet and outlet concentrations of the pollutant illustrated in Fig. 9, VOC conversion factor K = 99.9% was achieved throughout the initial phase. Fig. 9 Download : Download high-res image (337KB)Download : Download full-size image Fig. 9. VOC concentrations at bioreactor inlet and outlet, and VOC conversion factor determined during the initial phase of CTBB tests in full scale. Positive results of the initial phase of CTBB operation made it possible to allow air flowrate and pollutant concentration at the bioreactor inlet to fluctuate freely with changing parameters of the discharged stream of ventilation air. During the period of test operation, air flowrate varied in the range Vg = 300–6000 m3/h and the inlet concentration of the pollutant was changing between 5 ppm and 2000 ppm. At typical values of air flowrate between 4000 m3/h and 6000 m3/h, air pressure drop across bioreactor bed ranged between 150 Pa and 300 Pa. The results of measurements of pollutant concentrations performed during a representative time interval of 20 h, shown in Fig. 10, indicate considerable flexibility of the VOC biodegradation system. Despite the widely changing air flowrate and inlet concentration of VOCs, their concentration at the bioreactor outlet was maintained in the range of 0.1–55 ppm. At moderate values of inlet VOC concentration lower than, or just above 200 ppm, pollutant conversion factor not lower than 99% was achieved. Short-lived concentration peaks – above 1000 ppm, and sometimes as high as 1800 ppm – typically resulted in the reduction of the conversion factor to around 85%. However, each time VOC concentration was back at the moderate level, the conversion factor quickly returned to the range of 95–99%. Fig. 10 Download : Download high-res image (572KB)Download : Download full-size image Fig. 10. VOC concentrations at bioreactor inlet and outlet, and VOC conversion factor determined during a representative 20-h interval of CTBB tests in full scale. The tests of full-scale CTBB confirmed the optimal ranges of parameters of the biodegradation process, namely temperature 20–35 °C, and pH = 6.0–7.5. Regarding process safety, the concentration of carbon monoxide was found to vary between 0 and 40 ppm without detectable inhibitory effects. No explosion risk occurred as VOC concentration never exceeded 4% of LEL (lower explosive limit). 4. Discussion The experimental results presented in 1 Introduction, 2 Materials and methods, 3 Results and discussion.3 above can be compared with the results of research performed by other researchers on biodegradation of VOCs in biotrickling filters on a laboratory or pilot scale and summarized in the review paper by Rybarczyk et al. (2019). As long as moderate values below 200 ppm of pollutant concentration at bioreactor inlet were maintained during CTBB tests in both pilot and full scale, typical values of VOC conversion factor K = 95–99% obtained in the present research were comparable with the highest K values reported by other researchers. Moreover, while short-lived concentration peaks up to 1800 ppm were found to reduce the conversion factor to around 85%, its value quickly returned to the typical range as soon as VOC concentration was back at the moderate level. Apart from quantitative information acquired through measurements and processing of measurement data, important qualitative information was collected during the period of test operation of full-scale CTBB. As long as the values of process parameters were maintained within or close to their optimal ranges, VOC biodegradation was running smoothly and efficiently. However, when the processes conducted in the painting shop were modified resulting in the changed chemical composition of pollutants in the discharged ventilation air and subsequent pH increase in the liquid phase to 8.6–9.0, inhibitions of the biodegradation process were observed. These appeared to be cases of the impairment of biodegradability of VOCs mixture due to chemical interactions between some mixture components and degradation products of other co-existing components, analogous to those previously reported by Yoshikawa et al. (2017) who studied biodegradation of chlorinated ethylenes, benzene, toluene, and dichloromethane, and by Liao et al. (2018) who observed interaction effects in the biodegradation of benzene, toluene, xylene, and styrene. In the present work, problems of this kind were solved by adjusting the parameters of the painting processes and also supplying stronger buffer solutions to the control devices of the biodegradation system. As soon as pH in the liquid phase was back at a level close to 7.5, the microorganisms returned to their normal activity and efficient VOC biodegradation was quickly resumed. It was also observed at higher values of air flowrate, that excessive foaming of the circulating liquid phase occurs thus disturbing CTBB operation. This was recognized as a problem known from the experience with other applications of bioreactors (Delvigne and Lecomte, 2010). Corrective action was necessary to avoid foam spreading with the stream of purified air and to the industrial site area. From the range of foam prevention agents available on the market, a suitable defoamer – non-toxic and friendly to the microorganisms – was selected, and the functioning of the biodegradation system was brought back to normal by periodic dosing of the defoamer into the liquid phase upstream of the liquid distributor operated inside the bioreactor. Overall, the experimental results indicated a positive outcome of upscaling and adaptation of CTBB technology to the conditions of the automotive painting industry. The operation of the full scale bioreactor also confirmed the environmental friendliness of VOCs biodegradation. Energy demand is low, around 1 kWh per 1000 m3 air processed. (Energy is needed mainly for driving inverter-controlled pump that circulates the liquid phase, rated power 5,5 kW, and compensating for heat losses from thermally insulated bioreactor vessel where temperature 20–35 °C should be maintained, using electric heater rated 12 kW during periods of cold weather). Water demand is also low as water is needed mainly for offsetting vapor discharge in the stream of purified air that has been moisturized when in contact with liquid phase inside the bioreactor (order of magnitude 10 kg/h). Bearing in mind that the mass flow of degraded VOCs is rather small (usually less than 1 kg/h), there is no problem with solid waste as a part of pollutant mass is converted to bacterial biomass while biodegradation metabolites remain in the circulating liquid phase and can be periodically removed by liquid purge if needed. 5. Conclusions As a result of the sequence of research actions performed in the laboratory and at the industrial site, useful knowledge was gained on CTBB application to the biodegradation of VOCs emitted from the automotive painting industry. The established laboratory procedures made it possible to select the right type of micro-organisms and to adapt these to the target pollutants. Upon inoculation of CTBB in a pilot scale with the selected microorganisms, the bioreactor was installed and tested in the laboratory of Ekoinwentyka Ltd under strictly controlled process conditions. In a series of experiments, the CTBB performed satisfactorily and the microorganisms were found to degrade the VOCs efficiently. The bioreactor was later moved to the industrial site and used for biodegradation of VOCs discharged in air stream drawn from the ventilation system of the painting shop at flowrates between 1.0 and 10.0 m3/h and inlet concentration of VOCs ranging from 10 to 200 ppm. By measuring VOC concentrations both in the polluted and purified air, the factor of VOC biodegradation was found to range between 85 and 99%. The full-scale CTBB was installed in an industrial site as an add-on component of the ventilation system of a painting shop. Following successful immobilization of microorganisms and biofilm formation on the packing of bioreactor bed, a test programme was performed. The optimal ranges of parameters of the biodegradation process were confirmed as temperature 20–35 °C and pH = 6.0–7.5. At moderate values of VOC concentration in the air at CTBB inlet below 200 ppm, pollutant conversion factor not lower than 99% was maintained. Short-lived concentration peaks up to 1800 ppm were observed to reduce the conversion factor to around 85%. Overall, the tests proved highly efficient air purification in the bioreactor and the ability of CTBB to reduce VOC emissions in a sustainable way, that is, at mild operating conditions ensuring low energy consumption and avoidance of environmental risks. The biodegradation process proved robust as the microorganisms were able to survive VOC concentration peaks and other process disturbances and to resume their activity quickly after favourable process conditions have been restored. CRediT authorship contribution statement Damian Kasperczyk: Conceptualization, Investigation, Visualization, Project administration. Krzysztof Urbaniec: Methodology, Validation, Writing – original draft. Krzysztof Barbusiński: Methodology, Supervision, Writing – review & editing. Eldon R. Rene: Investigation, Writing – review & editing. Ramon F. Colmenares-Quintero: Investigation, Writing – review & editing. Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements The authors acknowledge the financial support received from the National Center for Research and Development, Warsaw, Poland under grant No. POIR.01.01.01-00-0664/17. Support and guidance from Warsaw University of Technology; Silesian University of Technology; IHE Delft Institute for Water Education and Universidad Cooperativa de Colombia are also acknowledged. References Álvarez-Hornos et al., 2011 F.J. Álvarez-Hornos, C. Lafita, V. Martínez-Soria, J.M. Penya-Roja, M.C. Pérez, C. Gabaldón Evaluation of a pilot-scale biotrickling filter as a VOC control technology for the plastic coating sector Biochem. Eng. J., 58–59 (2011), pp. 154-161 ArticleDownload PDFView Record in ScopusGoogle Scholar Bak et al., 2017 A. Bak, V. Kozik, P. Dybal, S. Sułowicz, D. Kasperczyk, S. 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Sci. Pollut. Res., 26 (10) (2019), pp. 9409-9434Yang et al., 2019 Z. Yang, J. Li, J. Liu, J. Cao, D. Sheng, T. Cai Evaluation of a pilot-scale bio-trickling filter as a VOCs control technology for the chemical fibre wastewater treatment plant J. Environ. Manag., 246 (2019), pp. 71-76Yoshikawa et al., 2017 M. Yoshikawa, M. Zhang, K. Toyota Integrated anaerobic-aerobic biodegradation of multiple contaminants including chlorinated ethylenes, benzene, toluene, and dichloromethane Water Air Soil Pollut., 228 (1) (2017) article No. 25Zhang et al., 2020 T. Zhang, G. Li, Y. Yu, Y. Ji, T. An Atmospheric diffusion profiles and health risks of typical VOC: numerical modelling study J. Clean. Prod., 275 (2020), Article 122982Compuestos orgánicos volátilesBiorreactor compacto de lecho de goteoTaller de pintura industrialSistema de ventilaciónBiodegradación de contaminantesVolatile organic compoundCompact trickle bed bioreactorIndustrial painting shopVentilation systemPollutant biodegradationDevelopment and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industryArtículos Científicoshttp://purl.org/coar/resource_type/c_2df8fbb1http://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionAtribucióninfo:eu-repo/semantics/closedAccesshttp://purl.org/coar/access_right/c_14cbPublicationORIGINAL2021_Development_technology_trickle-bed_licenciadeuso.pdf2021_Development_technology_trickle-bed_licenciadeuso.pdfLicencia de 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Development and adaptation of the technology of air biotreatment in trickle-bed bioreactor to the automotive painting industry

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