Contextualized project-based learning for training chemical engineers in graphic expression

Abstract This paper describes the planning of a computer-aided design (CAD) laboratory for training chemical engineers in graphic expression. The CAD laboratory was organised into four projects following a project-based learning method. Flipped classroom and contextualised learning were used to motivate the students and promote meaningful learning. The laboratory mainly focused on engaging the students by replicating 2D and 3D plans of common industrial engineering equipment and piping and instrumentation diagrams of industrial facilities. Two surveys carried out before and after the course showed that the student’s perception of their graphic expression skills significantly increased. Gend…

Removal of acetone from air emissions by biotrickling filters: providing solutions from laboratory to full-scale

A full-scale biotrickling filter (BTF) treating acetone air emissions of wood-coating activities showed difficulties to achieve outlet concentrations lower than 125 mg C m-3, especially for high inlet concentrations and oscillating emissions. To solve this problem, a laboratory investigation on acetone removal was carried out simulating typical industrial conditions: discontinuous and variable inlet concentrations and intermittent spraying. The results were evaluated in terms of removal efficiency and outlet gas emission pattern. Industrial emissions and operational protocols were simulated: inlet load up to 70 g C m-3 h-1 during 2 cycles of 4 h per day and intermittent trickling of 15 min …

Current challenges and perspectives in gas fluxes biotreatment

Abstract Nowadays, there is a wide variety of bioreactor configurations to treat specific pollutants from gas streams; however, biotechnologies share benchmark aspects that are herein described. In this chapter, the reader is introduced to the biological gas treatment field by means of a historical overview on how the initial devices used for gas treatment evolved to the innovative systems that are currently applied worldwide. The technical and operational fundamentals of biofilters, biotrickling filters, bioscrubbers, and emerging technologies such as two-phase partitioning bioreactors, multistage systems, and membranes are included. Perspectives and key research niches in the field are al…

Solvent production from rice straw by a co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae: effect of pH control

One of the challenges in biofuel production from lignocellulosic wastes is to improve its conversion to solvents; therefore, new strategies to enhance xylose uptake are required due to be the secondary abundant sugar. In this context, a novel fermentation strategy integrating a co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae with pH control was developed. Initially, two different buffers, ammonium acetate and calcium carbonate, were tested under pHmin > 4.8 by fermenting 60 g L−1 of glucose with the C. acetobutylicum monoculture. Ammonium acetate was selected for fermenting media as butanol production was increased from 9.8 to 10.9 g L−1 over the calcium carbonate test…

Modelling mass transfer properties in a biotrickling filter for the removal of isopropanol

A study was carried out to model mass transfer properties in biotrickling filters, treating isopropanol as the target pollutant. This study was extended to the mass transfer of oxygen related to the fact that the treatment of hydrophilic compounds by biotrickling filtration is often limited by oxygen. A simple method for each compound was developed based on their physical properties. The influence of temperature on the Henry"s law constant of isopropanol was determined. An increase of 1.8 per 10ºC for the dimensionless Henry"s law constant was obtained. The determination of the overall mass transfer coefficients of isopropanol (KGa) was carried out, obtaining values between 500 and 1800 h-1…

Evolution of Bacterial Community in a Full-scale Biotrickling Filter by Fluorescence in Situ Hybridization (FISH)

The performance of a full-scale biotrickling system for the treatment of exhaust gases from two different paint sources at a furniture facility, was investigated applying Fluorescense in situ hybridization (FISH). This technique allowed the detection of major bacteria groups and, therefore, helped in understanding complex microbial communities. The results indicated that Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria were more predominant than Firmicutes and Actiniobacterias. In addition, a variation in the composition of the bacterial community throughout the time of operation and with the paint source was observed. Betaproteobacteria showed similar r…

Fed-batch simultaneous saccharification and fermentation including in-situ recovery for enhanced butanol production from rice straw

Abstract This paper describes a study of fed-batch SSFR (simultaneous saccharification, fermentation and recovery) for butanol production from alkaline-pretreated rice straw (RS) in a 2-L stirred tank reactor. The initial solid (9.2% w/v) and enzyme (19.9 FPU g-dw-1) loadings were previously optimized by 50-mL batch SSF assays. Maximum butanol concentration of 24.80 g L-1 was obtained after three biomass feedings that doubled the RS load (18.4% w/v). Butanol productivity (0.344 g L-1h−1) also increased two-fold in comparison with batch SSF without recovery (0.170 g L-1h−1). Although fed-batch SSFR was able to operate with a single initial enzyme dosage, an extra dosage of nutrients was requ…

Workshops of innovation in chemical engineering to train communication skills in science and technology

Abstract This paper shows the application of an innovate pedagogical approach based on the project-based learning technique, focused on the training of communication skills in the framework of a workshop of innovation in chemical engineering. Written, graphical verbal, and non-verbal communication were tackled. For that purpose, a project of technological innovation was developed by the students in teams within the specific area of chemical engineering. A professional-like environment was simulated by a final workshop where the students defenced and supported their project by using oral presentation and production of a poster and a video. Several surveys were performed before and after the …

A Tool for Predicting the Dynamic Response of Biotrickling Filters for VOC Removal

This article presents the development of a MATLAB® computer program to simulate the performance of biotrickling filters. Since these filters behave differently during spraying and nonspraying cycles, the presented simulation tool is built on top of a mathematical description of each situation. The resulting variable-structure model is then used as the basis for simulation experiments. The model presented herein represents the first attempt to take into account the variable spraying pattern usually found in industrial installations. Overall, the software is flexible and easy to use, allowing the user to specify the emission concentration pattern, the gas concentration pattern, as well as the…

Modelling mass transfer properties in a biotrickling filter for the removal of isopropanol

Abstract A study was carried out to model mass transfer properties in biotrickling filters, treating isopropanol as the target pollutant. This study was extended to the mass transfer of oxygen related to the fact that the treatment of hydrophilic compounds by biotrickling filtration is often limited by oxygen. A simple method for each compound was developed based on their physical properties. The influence of temperature on Henry’s law constant of isopropanol was determined. An increase of 1.8 per 10 °C for the dimensionless Henry’s law constant was obtained. The determination of the overall mass transfer coefficients of isopropanol (KGa) was carried out, obtaining values between 500 and 18…

Performance of a polypropylene membrane contactor for the recovery of dissolved methane from anaerobic effluents: Mass transfer evaluation, long-term operation and cleaning strategies

Abstract A polypropylene membrane contactor was used for the recovery of dissolved methane from an anaerobic reactor effluent. Effect of operational parameters, operation mode and fouling on long-term operation was studied using vacuum pressure or N 2 as sweep gas. Results were analyzed based on the mass transfer estimations. Lower performance was observed in the shell-side mode due to the lower liquid velocity and the probable channeling. Membrane pore wetting was observed with the increase in Q L in the vacuum-pressure mode. This was confirmed with mass transfer resistance analysis, resulting in an estimated wetted pore fraction of between 0.25 and 0.53. The highest removal efficiencies w…

Enhanced styrene removal in a two-phase partitioning bioreactor operated as a biotrickling filter: Towards full-scale applications

Abstract Styrene vapor abatement was investigated in a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The removal performance of the TPPB-BTF was simultaneously compared with a conventional BTF, which served as a control. Industrial-grade silicone oil was used as the non-aqueous phase in the TPPB-BTF due to its high affinity for styrene. Both bioreactors were operated at styrene inlet concentrations ranging from 55 to 323 mg C m −3 and empty bed residence times (EBRT) of 15–30 s, corresponding to pollutant loading rates of 13–77 g C m −3  h −1 . Both bioreactors exhibited styrene removal efficiencies (REs) higher than 90% at an EBRT of 30 s. Nevertheless, th…

Evolution of bacterial community in isopropanol-degrading biotrickling filters by fluorescence in situ hybridization (FISH)

In this study, the bacterial population of two biotrickling filters (BFTs) treating isopropanol by using fluorescence in situ hybridization (FISH) is analyzed. The experimental system consists in two identical laboratoryscale BFTs named as BFT1 and BFT2. The two bioreactors were operated in parallel during an experimental period of one year working under intermittent feeding conditions Operating conditions and maintenance were identical in both BFT.

Biotrickling filter modeling for styrene abatement. Part 2: Simulating a two-phase partitioning bioreactor.

Abstract A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase. The three phases considered were gas, a water–silicone liquid mixture, …

Biotrickling filtration of isopropanol under intermittent loading conditions

This paper investigates the removal of isopropanol by gas phase biotrickling filtration. Two plastic packing materials, one structured and one random, have been evaluated in terms of oxygen mass transfer and isopropanol removal efficiency (RE). Oxygen mass transfer experiments were performed at gas velocities of 104 and 312 m h-1 and liquid velocities between 3 and 33 m h-1. Both materials showed similar mass transfer coefficients up to liquid velocities of 15 m h-1. At greater liquid velocities, the structured packing exhibited greater oxygen mass transfer coefficients. Biotrickling filtration experiments were carried out at inlet loads (IL) from 20 to 65 g C m-3 h -1 and empty bed residen…

Study of Mass Oxygen Transfer in a Biotrickling Filter for Air Pollution Control

Biotrickling filtration is a potential and cost effective alternative for the treatment of volatile organic compound (VOC) emissions in air, so it is necessary to deepen into the key aspects of design and operation for the optimization of this technology. One of these factors is the oxygen mass transfer of the process. This study would facilitate the selection of the packing material and the mathematical modelling and simulation of bioreactors. Four plastic packing materials with a different specific surface area have been evaluated in terms of oxygen mass transfer. For the tested range of superficial liquid velocities, data show a relationship between the kLa and the superficial liquid vel…

Aspen Plus process-simulation model: Producing biogas from VOC emissions in an anaerobic bioscrubber

A process-simulation model for a novel process consisted of an anaerobic bioscrubber was developed in Aspen Plus®. A novel approach was performed to implement the anaerobic reactor in the simulation, enabling it to be connected to the scrubber. The model was calibrated and validated using data from an industrial prototype that converted air emissions polluted with volatile organic compounds with an average daily concentration of 1129 mgC Nm−3 into bioenergy for more than one year. The scrubber, which showed a removal efficiency within 83-93%, was successfully predicted with an average absolute relative error of 5.2 ± 0.08% using an average height-to-theoretical-plate value of 1.05 ± 0.08 m …

Microbial community analysis in biotrickling filters treating isopropanol air emissions

The evolution of the microbial community was analysed over one year in two biotrickling filters operating under intermittent feeding conditions and treating isopropanol emissions, a pollutant typically found in the flexography sector. Each reactor was packed with one media: plastic cross-flow-structured material or polypropylene rings. The communities were monitored by fluorescence in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rRNA region. After inoculation with activated sludge, the biotrickling filters were operated using inlet loads (ILs) from 20 to 65gCm−3 h−1 and empty-bed residence times (EBRTs) from 14 to 160 s. Removal efficienci…

Optimization of alkali pretreatment to enhance rice straw conversion to butanol

Abstract The use of rice straw (RS) was enhanced to produce biobutanol as biofuel, for which the NaOH pretreatment was optimized by considering the butanol-biomass ratio that quantify the mass balance efficiency of the three sequential stages of the process: pretreatment, enzymatic hydrolysis and fermentation by Clostridium beijerinckii. The optimum point (solid loading of 5% w/v with 0.75% w/v NaOH at 134 °C for 20 min) of the best cost-wise option yielded an enhanced biomass use of 77.6 g kg RS−1. A maximum butanol titer of 10.1 g L−1 was reached after 72 h of fermentation with the complete uptake of glucose and nearly complete uptake of xylose. The NaOH concentration was the most influen…

Anaerobic degradation of glycol ether-ethanol mixtures using EGSB and hybrid reactors: Performance comparison and ether cleavage pathway.

Abstract The anaerobic biodegradation of ethanol-glycol ether mixtures as 1-ethoxy-2-propanol (E2P) and 1-methoxy-2-propanol (M2P), widely used in printing facilities, was investigated by means of two laboratory-scale anaerobic bioreactors at 25oC: an expanded granular sludge bed (EGSB) reactor and an anaerobic hybrid reactor (AHR), which incorporated a packed bed to improve biomass retention. Despite AHR showed almost half of solid leakages compared to EGSB, both reactors obtained practically the same performance for the operating conditions studied with global removal efficiencies (REs) higher than 92% for organic loading rates (OLRs) as high as 54 kg of chemical oxygen demand (COD) m−3 d…

Enhancement of biomass retention in an EGSB reactor used to treat 1-methoxy-2-propanol

Fully aerobic bioscrubber for the desulfurization of H2S-rich biogas

Abstract A fully aerobic bioscrubber for the desulfurization of H2S-rich biogas was developed in the present study by coupling an absorption column and a bubble column bioreactor. The bioscrubber treated H2S loading rates of 37, 59, and 100 g S mliquid−3 h−1 at gas residence times of 6.6, 4.1 and 2.4 min in the absorption column, respectively. Stable H2S removal efficiencies above 80% were recorded at all the conditions tested. The bioscrubber was robust towards short- and long-term operation shutdowns (5 and 18 days), the H2S removal performance being recovered after few hours. The aerated bubble column bioreactor was operated at slightly alkaline conditions (pH 8 ± 0.5), which prevented H…

Biotrickling filter modeling for styrene abatement. Part 1: Model development, calibration and validation on an industrial scale

Abstract A three-phase dynamic mathematical model based on mass balances describing the main processes in biotrickling filtration: convection, mass transfer, diffusion, and biodegradation was calibrated and validated for the simulation of an industrial styrene-degrading biotrickling filter. The model considered the key features of the industrial operation of biotrickling filters: variable conditions of loading and intermittent irrigation. These features were included in the model switching from the mathematical description of periods with and without irrigation. Model equations were based on the mass balances describing the main processes in biotrickling filtration: convection, mass transfe…

The combined effect on initial glucose concentration and pH control strategies for acetone-butanol-ethanol (ABE) fermentation by Clostridium acetobutylicum DSM 792

Abstract The use and depletion of fossil fuels raised the interest in biofuels like biobutanol. Clostridium acetobutylicum DSM 792 is capable of producing biobutanol through ABE fermentation. Butanol production can be influenced by low sugar concentrations, like those obtained after hydrolysis of pre-treated lignocellulosic biomass. This study aimed to evaluate the influence of the initial glucose concentrations (33, 66 and 100 g L−1) and pH control strategies on biobutanol production and glucose consumption. Uncontrolled pH fermentation exhibited low butanol production due to either glucose exhaustion (33 g L−1) or the phenomenon of acid crash (66 and 100 g L−1), which was alleviated by th…

Granulation and microbial community dynamics in the chitosan-supplemented anaerobic treatment of wastewater polluted with organic solvents.

Abstract The effect of chitosan on the development of granular sludge in upflow anaerobic sludge blanket reactors (UASB) when treating wastewater polluted with the organic solvents ethanol, ethyl acetate, and 1-ethoxy-2-propanol was evaluated. Three UASB reactors were operated for 219 days at ambient temperature with an organic loading rate (OLR) of between 0.3 kg COD m −3 d −1 and 20 kg COD m −3 d −1 . One reactor was operated without the addition of chitosan, while the other two were operated with the addition of chitosan doses of 2.4 mg gVSS −1 two times. The three reactors were all able to treat the OLR tested with COD removal efficiencies greater than 90%. However, the time required to…

Effect of the height-to-diameter ratio on the mass transfer and mixing performance of a biotrickling filter

BACKGROUND Biotrickling filters (BTFs) are among the most widely used biological technologies for air pollution control. The pollutant removal rate in BTFs relies to a large extent on its gas–liquid mass transfer performance. Therefore, knowledge of the design parameters affecting the mass transfer and mixing performance of full-scale BTFs is of paramount importance. RESULTS This work showed that the height-to-diameter (H/D) ratio is an important parameter in the design of BTFs devoted to air pollution control. The H/D ratio significantly affected the mass transfer and mixing performance of the BTF with and without additional stirring in the holding tank. It was observed that under the same…

Anaerobic degradation of 2-propanol: Laboratory and pilot-scale studies

Abstract The anaerobic degradation of 2-propanol, an important industrial solvent, was scaled-up from batch assays to a pilot expanded granular sludge bed (EGSB) reactor at 25 °C. Batch studies indicated that 2-propanol followed Haldane kinetics, with a maximum rate at 10 g COD L −1 . Concentrations as high as 25 g COD L −1 did not inhibit the degradation of ethanol, a common co-solvent. Similar specific methanogenic activities (SMA) were obtained for water-solvent and water-brewery sludges (88 and 77 ml CH 4  g-VS −1  d −1 at 5 g COD L −1 ). Continuous degradation showed a lag-phase of three weeks with water-brewery sludge. Increases in 2-propanol load from 0.05 to 0.18 kg COD kg-VS −1  d …

Dynamic Mathematical Modelling of the Removal of Hydrophilic VOCs by Biotrickling Filters

A mathematical model for the simulation of the removal of hydrophilic compounds using biotrickling filtration was developed. The model takes into account that biotrickling filters operate by using an intermittent spraying pattern. During spraying periods, a mobile liquid phase was considered, while during non-spraying periods, a stagnant liquid phase was considered. The model was calibrated and validated with data from laboratory- and industrial-scale biotrickling filters. The laboratory experiments exhibited peaks of pollutants in the outlet of the biotrickling filter during spraying periods, while during non-spraying periods, near complete removal of the pollutant was achieved. The gaseou…