Eric Dumont

University of Nantes | UNIV Nantes · Laboratoire de génie des procédés, environnement, agroalimentaire (GEPEA)

A hybrid desulfurization process combining a physical filtration stage on cellular concrete (CC abiotic filter, called CCAF) and a biotrickling filter (called BTF) filled with expanded schist as packing material was used to remove high H2S concentrations from a synthetic gas containing dinitrogen (N2), dioxygen (O2) and H2S without the addition of...

The treatment of a synthetic polluted gas containing seven volatile organic compounds (VOCs) was studied using a pilot plant in real industrial conditions. The process combined VOC absorption in silicone oil (PolyDiMethylSiloxane, i.e., PDMS), a biological regeneration of the PDMS in a two-phase partitioning bioreactor (TPPB), and a phase separatio...

A two-stage desulfurization process including an abiotic filtration using cellular concrete waste (first stage) and an anoxic biotrickling filter filling with an inoculated expanded schist material (second stage) was investigated to remove H2S in mimic biogas with limited O2 amount (ranged from 0.5 to 0.8%). The two-stage process was able to satisf...

It was demonstrated that the daily monitoring of electrical conductivity (EC) of scrubbing water can easily be used to determine the performance of biotrickling filters treating ammonia (NH3) emissions, generated by livestock facilities. Two different measurement campaigns were carried out on a pilot-scale biotrickling filter installed at a pig fac...

It is emphasized that a generalized relationship can be used to predict the ionic nitrogen concentration (i.e., sum of ammonium NH4+, nitrite NO2− and nitrate NO3−) of the scrubbing liquid in a biotrickling filter treating ammonia emissions by measuring the electrical conductivity (EC) of the water directly. From measurements carried out on differe...

From theoretical calculations validated by the results of experiments, it was shown that the properties of the washing liquid that flows into biotrickling filters at livestock facilities determine the maximum ammonia removal efficiency (RE) that can be achieved. For a well-designed biotrickling filter not limited by hydrodynamic conditions, the amm...

A process in three steps involving a gas-liquid contactor with an organic phase, a TPPB and a liquid/liquid separator to recover the organic phase for its recycling was proposed to treat hydrophobic Volatile Organic Compounds. Among the processes tested for liquid/liquid separation (settling, hydrocyclone and centrifugation), the latter appeared to...

From biofiltration to promising options in gaseous fluxes biotreatment: recent developments, new trends, advances, and opportunities provides an overview on the biological tools used for the treatment of the gaseous fluxes, with emphasis on traditional and perspective options, opening new horizons for research and implementation in practice. It is...

A new tool to determine the Specific Nitrogen Accumulation Rate (SNAR expressed in gNH3 h⁻¹ m⁻³packingmaterial) in the washing liquid of a biotrickling filter for treating ammonia (NH3) emissions is proposed. The tool is based on the relationship which exists between the electrical conductivity (EC) of the water and the amount of nitrogen salts dis...

In this study, the Effectiveness-NTU method, which is usually applied to heat exchanger design, was adapted to gas–liquid countercurrent absorbers to determine the overall mass transfer coefficient, KLa, of the apparatus in operation. It was demonstrated that the ε-NTU method could be used to determine the KLa using the Henry coefficient of the sol...

The removal of hydrogen sulfide (H 2 S) in air using cellular concrete waste as packing material was investigated and compared to results obtained with expanded schist. Air filtration was performed under abiotic conditions. Experiments were carried out in 3 laboratory-scale PVC columns (internal diameter of 100 mm) filled with a volume of 7.8 L of...

This chapter describes the mass transfer characteristics in gas/water/organic solvent systems. The ability of an organic solvent (called NAP, i.e., Non Aqueous Phase) to influence the gas transfer of solutes (Volatile Organic Compounds, VOCs, or oxygen) from the gas phase to the aqueous phase and to affect the gas/liquid interface and the volumetri...

The Effectiveness-Number of Transfer Unit method (ε-NTU method) was applied to determine the overall mass transfer coefficient, KLa, of operating gas-liquid absorbers treating Volatile Organic Compounds (VOCs). This method requires the knowledge of the operating conditions (gas flow rate, QG; liquid flow rate, QL; scrubber volume V), the measuremen...

An analytical pore-scale model is proposed for predicting the pressure drop of a biofilter by taking the effect of biofilm development into account. Besides the average particle radius and fluid parameters, the pressure drop is expressed in terms of the initial bed porosity, the biofilm affected porosity, particle sphericity, surface roughness coef...

In order to limit ammonia (NH3) emissions from pig farms, various air cleaning solutions are widely applied. However, the literature data report that these systems (chemical scrubbers, bioscrubbers and biofilters) can be both inefficient and promote nitrous oxide (N2O) production. As air cleaning technologies should not contribute to secondary trac...

The biofiltration of hydrogen sulfide present in a biogas mimic under anoxic conditions was performed using expanded schist and cellular concrete waste as packing materials. The impact of various parameters, such as H2S concentrations, Empty Bed Residence Time (EBRT) and molar ratio N/S, on the performances of biofilters was evaluated. At an EBRT o...

This study introduces a new strategy to determine the maximum Elimination Capacity (ECmax) of a biofilter within a 10% error from a single experiment of 2 hours. The procedure requires several ports for H2S measurement along the length of the biofilter in order to establish accurately the relative concentration profile versus the residence time of...

The performances of a laboratory PhotoCatalytic Oxidation (PCO) device were determined using a recirculation closed-loop pilot reactor. The closed-loop system was modeled by associating equations related to two ideal reactors: a perfectly mixed reservoir with a volume of VR = 0.42 m3 and a plug flow system corresponding to the PCO device with a vol...

This study demonstrated that a laboratory-scale recirculation closed-loop reactor can be an efficient technique for the determination of the Clean Air Delivery Rate (CADR) of PhotoCatalytic Oxidation (PCO) air purification devices. The recirculation closed-loop reactor was modeled by associating equations related to two ideal reactors: one is a per...

The objective of this study was to investigate the removal of hydrogen sulfide (H2S) present in air using cellular concrete waste as the packing material. Air filtration was performed under biotic and abiotic conditions. Experiments were carried out in a laboratory-scale PVC column (internal diameter of 300 mm) filled with a volume of 70 L of cellu...

The performances of two identical biofilters, filled with a new composite packing material (named CM-5) embedded with functional microorganisms or sterilized CM-5 without microorganisms, were investigated for H2S treatment. Running parameters in terms of microbial counts, pressure drops, and inlet and outlet H2S concentrations were measured. The re...

Toluene degradation performances were studied in a 10 L Two-Phase Partitioning Bioreactor (TPPB). The liquid phase consisted of a mixture of water and PDMS 50 (PolyDiMethylSiloxane, i.e. silicone oil, viscosity of 46 mPa·s) in the volume ratio of 75%/25%. Two series of experiments were carried out: in the first, the reactor was sequentially supplie...

Experimental measurements of pressure drops through three biofilters filled with expanded schist for H2S degradation were used to determine the change in the porosity of packed beds over time, and to calculate the thickness of biofilms covering the material. Three mathematical models characterizing the fluid flow through porous media were used for...

The treatment of hydrogen sulfide using a biofilter packed with expanded schist and topped with a layer of a synthetic nutritional material (UP20) was examined at a constant H2S concentration (100 ppmv). The impact of the empty bed residence time (EBRT) on process performances was clearly underlined by varying the polluted air flow from 4 to 20 m3...

A compositepacking material (CM-5) waspreparedin this study,mainly consisting of compost with functional microorganisms, calcium carbonate (CaCO3), perlite, cement and plant fiber. To get stronger compressive strength, mass ratios of these components were optimized based on single factor experiments, and finally adding amounts of perlite, cement, p...

The purpose of this study was to compare toluene absorption performances using two PDMS of different viscosities (η = 5 and 50 mPas respectively) in terms of hydrodynamics and mass transfer. Three types of packing were tested in a counter-current packed gas-liquid contactor, Raschig rings, IMTP®, and Flexipac®. Hydrodynamic results showed that the...

An innovative mathematical description of TPPBs was developed. Potential VOC uptake from the NAP and aqueous phase renewal were considered. The model was validated with experimental data from literature. No parameter fitting was carried out for model validation. g r a p h i c a l a b s t r a c t a b s t r a c t Two-phase partitioning bioreactors (T...

Background Four silicone oils (PolyDiMethylSiloxane, PDMS) of different viscosities, namely 5, 20, 50, and 100 mPa s were characterized to select the most suitable polymer for the biological treatment of toluene. The PDMS volatilities and the partition coefficients of toluene between air and PDMS were investigated. Toluene biodegradation tests were...

BackgroundH2S biofiltration was carried out using expanded schist as packing material completed with a synthetic material (UP20). A comparison of different hydrodynamic configurations was made based on biofilter performances and pressure drop measurements. Three biofilters (namely BF52, BF102 and BF160) differing in bed height (52 cm, 102 cm and 16...

An above ground pilot-scale biofilter filled with wood chips was tested to treat ammonia emissions from a piggery located in Brittany (France). A long-term experiment corresponding to the fattening period was carried out during 124 days (from October 13th 2012 to February 5th 2013) at a constant Empty Bed Residence Time (EBRT = 12 s). NH3 concentra...

An above ground pilot-scale biofilter filled with wood chips was tested to treat ammonia emissions from a piggery located in Brittany (France). A long-term experiment corresponding to the fattening period was carried out to improve biofilter applications for agriculture. NH3 concentrations at the inlet of the biofilter mainly ranged between 8 and 1...

This study aims to evaluate the feasibility of using a nutritional synthetic material (UP20) combined with fibrous peat as a packing material in treating H2S (up to 280 ppmv). Three identical laboratory-scale biofilters with different packing material configurations (peat only; peat + UP20 in a mixture; peat + UP20 in two layers) were used to deter...

The swine industry follows a large increase of meat production since the 1950s causing the development of bigger swine buildings which involves a raise of pollutants emissions. Due to recent anthropological pressures concerning the animal welfare, the limitation of neighborhood disturbances and atmospheric pollutions limitations, the livestock farm...

The absorption of styrene in water/silicone oil systems at a constant flow rate for emulsion compositions ranging from 0% to 20% was investigated using a dynamic absorption method. It was found that the mass transfer for air/water/silicone oil systems is roughly double than those determined for air/water systems whatever the silicone oil percentage...

The performances of three laboratory-scale biofilters (BF1, BF2, BF3) packed with expanded schist for H(2)S removal were studied at different empty bed residence times (EBRT=35, 24 and 16s) in terms of elimination capacity (EC) and removal efficiency (RE). BF1 and BF2 were filled with expanded schist while BF3 was filled with both expanded schist a...

During biological degradation, such as biofiltration of air loaded with volatile organic compounds, the pollutant is passed through a bed packed with a solid medium acting as a biofilm support. To improve microorganism nutritional equilibrium and hence to enhance the purification capacities, a Biological Activator Formulated Material (BAFM) was dev...

The effect of activated sludge acclimation on the biodegradation of toluene and dimethyldisulphide (DMDS) in the presence of a non-aqueous phase liquid, polydimethylsiloxane (PDMS), in a two-phase partitioning bioreactor was characterized. The influence of the presence of PDMS, at a ratio of 25% (v/v), and acclimation of activated sludge on two hyd...

BACKGROUND: The aim of this work was to test an innovative packing material (expanded schist) for H2S biofiltration in order to determine the packing material performance in terms of elimination capacity, removal efficiency and pressure drop changes. Additionally, the changes over time of bed characteristics, especially tortuosity, were evaluated a...

BACKGROUND: This study deals with the potential of biological processes combining biofiltration and a biotrickling filter to treat a mixture of sulphur reduced compounds (SRC) including dimethylsulfide (DMS), dimethyldisulfide (DMDS) and hydrogen sulphide (H2S). The first step in this work is to evaluate the influence of pH on SRC biodegradation in...

A methodology to determine the diameter of an absorber contacting a gas phase and two immiscible liquid phases (water/silicone oil mixture) is presented. The methodology is applied to a countercurrent gas/liquid randomly packed column for the absorption of three VOCs (toluene, dimethyl sulfide, or dimethyl disulfide). Whatever the silicone oil volu...

Through the framework of the aerial pollutants removal from the atmosphere of piggeries using a biofilter, this paper focuses on the effect of the presence of dust on the design of the biofilter. Simultaneous measurements (dust size distribution, dust concentration and NH3 concentrations) are carried out in the casing of the piggery air extraction....

A calculation procedure to determine the influence of the silicone volume fraction on the physical absorption of VOCs in water/silicone oil mixtures is presented (ηsilicone oil = 5 mPa s). It is based on the “equivalent absorption capacity” concept previously developed by Dumont et al. (2010) [1] and applied to a countercurrent gas–liquid absorber....

The main objective of this work was to propose a model able to predict the partition coefficient of odorous or toxic gaseous pollutants (dimethylsulphide, dimethyldisulphide and toluene) in water/silicone oil mixtures. Experimental measurements using a static headspace method were carried out for pure water (Hvoc,water), for pure silicone oil (Hvoc...

BACKGROUND: Hydrophobic volatile organic compounds (VOCs), such as toluene, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), are poorly soluble in water and classical air treatment processes like chemical scrubbers are not efficient. An alternative technique involving an absorption step in an organic solvent followed by a biodegradation phase...

The biofiltration of gas polluted with H2S was carried out using innovative configurations of packing materials (i.e. a new synthetic material called UP20, sapwood, peat, pozzolan and pine bark). A comparison of seven different configurations (media alone or in combination) was made based on biofilter performances and pressure drop measurements. Bi...

Biological air treatment is largely used for the decontamination of large air streams with low pollutant concentrations. As a result of microbial metabolism, the pollutants are degraded into carbon dioxide and water or converted into cell biomass. Three main research domains have emerged within the field of biofiltration: filter bed development, pr...

This study aims to evaluate the feasibility of using a new packing material (UP20) in treating H2S. Three identical laboratory-scale biofilters, filled with, respectively, UP20 alone, pine bark, and a configuration made of two layers of pozzolan/UP20 (80/20, v/v), were used for critical comparison. Various concentrations of H2S (up to 100 ppmv) wer...

Experimental results of mass transfer in air-water system with a dispersed immiscible organic liquid in a bubble column 0.076 m in diameter for seven different organic liquids at various hold-up are presented. Experiments are carried out at gas superficial velocity in the range 0.0052-0.026 m/s at 293 K. The volumetric mass transfer coefficient, kL...

In this study, an inverse method is presented so as to determine the wall shear rate in a scraped surface heat exchanger using polarography technique. Based on a numerical sequential estimation, this method which enables the inversion of the convection diffusion equation, is applied to measured mass transfer temporal signals. Other solutions, mostl...

Biotechnology has been applied to find green and low cost environmental processes. In the waste gas treatments (odours and volatile organic compounds VOC) one of the main biological systems used is biofilters. This technology works at normal operating conditions of temperature and pressure, and therefore it is relatively cheap with high efficiencie...

The absorption of oxygen and styrene in water–silicone oil emulsions was independently studied in laboratory-scale bubble reactors at a constant gas flow rate for the whole range of emulsion compositions (0–10% v/v). The volumetric mass transfer coefficients to the emulsions were experimentally measured using a dynamic absorption method. It was ass...

The absorption of oxygen in aqueous–organic solvent emulsions was studied in a laboratory-scale bubble reactor at a constant gas flow rate. The organic and the gas phases were dispersed in the continuous aqueous phase. Volumetric mass transfer coefficients (kLa) of oxygen between air and water were measured experimentally using a dynamic method. It...

A review is presented on the gas–liquid mass transfer enhancement due to the presence of a second dispersed liquid phase. An attempt has been made to describe the mass transfer characteristics in a gas–liquid–liquid system. The ability of an immiscible oil phase to influence the possible pathway for gas transfer from the gas phase to the aqueous ph...

An experimental investigation was done by the use of visual observations and the electrochemical technique in order to study the appearance of hydrodynamic instabilities at low Reaxg in the gap between two coaxial cylinders, with radius ratio Rr/Rs=0.615 and aspect ratio L/e=24. A motor drove the inner cylinder and the outer cylinder was fixed. A N...

An experimental investigation of a scraped surface heat exchanger (SSHE) was undertaken using visual observations and the electrochemical technique in order to, firstly, study the transition between laminar and vortex flows and, secondly, evaluate the wall shear rates. Visual observations and the electrochemical technique had undergone preliminary...

In industrial applications, fluids processed in scraped surface heat exchangers often show large temperature heterogeneities at the exchanger outlet. Our study deals with the thermal evolution of model fluids, Newtonian and non-Newtonian in heating or cooling conditions and allows us to link the phenomena of appearance and disappearance of temperat...

An electrochemical technique was used to measure local and instantaneous wall shear rates in a scraped surface heat exchanger (SSHE). The inner cylinder, equipped with two blades symmetrically opposed, was driven by a stepping motor and the outer cylinder was fixed. Highly viscous Newtonian fluids (Emkarox HV45 solutions) and non-Newtonian model fl...

The molecular diffusion of ferricyanide ions in polymeric Newtonian and non-Newtonian solution has been studied at 25°C with different experimental methods: rotating-disc flow, Couette-flow and unsteady diffusion. It is shown that the Levich equation established for the determination of diffusion coefficients with the rotating-disc electrode method...

This study aims to evaluate the feasibility of using a new synthetic material (called UP20) associated with fibrous peat as packing material in treating H2S. Three identical laboratory-scale biofilters were used for critical comparison. The first was filled with 100% peat; the second was filled with peat mixed with UP20 (80/20 v/v); and a configura...

The objective of this work was to evaluate the hydrogen storage capacities of various activated carbon materials in form of granules, powders, fibers and clothes under cryogenic and ambient temperature conditions (77K -293K), at pressures up to 30Bar. The experimental data were analyzed for carbon samples covering a wide range of BET surfaces and m...