Feliu Sempere

Performance evaluation of a biotrickling filter treating a mixture of oxygenated VOCs during intermittent loading

Laboratory scale-studies on the biodegradation of a 1:1:1 weight mixture of three oxygenated volatile organic compounds (VOCs), ethanol, ethyl acetate, and methyl-ethyl ketone (MEK) in a biotrickling filter (BTF) were carried out using two identically sized columns, filled with different polypropylene rings. The performance of the BTFs was examined for a period of 10 months applying several operational strategies. Similar performance was obtained for both supports. Intermittent flow rate of trickling liquid was shown beneficial to improve the removal efficiency (RE). Continuous feeding of VOC resulted in an excessive accumulation of biomass so high pressure drop was developed in less than 20-30 d of operation. Intermittent VOC loading with night and weekend feed cut-off periods passing dry air, but without addition of water, was shown as a successful operational mode to control the thickness of the biofilm. In this case, operation at high inlet loads (ILs) was extended for more than 75 d maintaining high REs and low pressure drops. Outlet emission concentrations lower than 100 mg Cm(-3) were obtained for ILs up to 100 g Cm(-3)h(-1) working at 15s of empty bed residence time. The most easily biodegradable compounds ethanol and ethyl acetate were used primarily than MEK. After a 3-wk-starvation period, the system performance was almost restored since the first d of operation, being the removal of the less biodegradable compound, MEK, partially deteriorated.

Performance of a Pilot-Scale Biotrickling Filter in Controlling the Volatile Organic Compound Emissions in a Furniture Manufacturing Facility

Abstract A 0.75-m3 pilot-scale biotrickling filter was run for over 1 yr in a Spanish furniture company to evaluate its performance in the removal of volatile organic compounds (VOCs) contained in the emission of two different paint spray booths. The first one was an open front booth used to manually paint furniture, and the second focus was an automatically operated closed booth operated to paint pieces of furniture. In both cases, the VOC emissions were very irregular, with rapid and extreme fluctuations. The pilot plant was operated at an empty bed residence time (EBRT) ranging from 10 to 40 sec, and good removal efficiencies of VOCs were usually obtained. When a buffering activated carbon prefllter was installed, the system performance was improved considerably, so a much better compliance with legal constraints was reached. After different shutdowns in the factory, the period to recover the previous performance of the biotrickling reactor was minimal. A weekend dehydration strategy was developed and implemented to control the pressure drop associated with excessive biomass accumulation.

Hydrogen sulfide and odor removal by field-scale biotrickling filters: influence of seasonal variations of load and temperature.

Two biotrickling filters were set up at two wastewater treatment plants (WWTP) in The Netherlands to investigate their effectiveness for treatment of odorous waste gases from different sources. One biotrickling filter was installed at Nieuwe Waterweg WWTP in Hook of Holland to study the hydrogen sulfide removal from headworks waste air. The other reactor was installed at Harnaschpolder WWTP (treating wastewater of the city of The Hague) to remove mercaptans and other organic compounds (odor) coming from the emissions of the anaerobic tanks of the biological nutrient removal (BNR) activated sludge. The performance of both units showed a stable and highly efficient operation under seasonal variations of load and temperature over nearly one year of monitoring. The Nieuwe Waterweg unit achieved removals of up to 99%, corresponding to a maximum daily average elimination capacity (EC) of 55.8 g H2S/m3/h at an empty bed residence time (EBRT) as short as 8.5 s. Odor reduction at the Harnaschpolder unit was 95% at an EBRT of 18.9 s, with average outlet concentration lower than the objective value which was established as 1000 European Odor Units (OUE/m3).

Influence of ground tire rubber on the transient loading response of a peat biofilter.

The effect of using ground tire rubber (GTR) as an adsorptive material in the removal of a 2:1:1 weight mixture of n-butyl acetate, toluene and m-xylene by using a peat biofilter under different intermittent conditions was investigated. The performance of two identical size biofilters, one packed with fibrous peat alone and the other with a 3:1 (vol) fibrous peat and GTR mixture, was examined for a period of four months. Partition coefficients of both materials were measured. Values of 53, 118 and 402 L kg(-1) were determined for n-butyl acetate, toluene and m-xylene in peat, respectively; and values of 40, 609 and 3035 L kg(-1) were measured for the same compounds in GTR. Intermittent load feeding of 16 h per day, 5 days per week working at an EBRT of 60 s and an inlet VOC concentration of 0.3 g C m(-1), resulted in removal efficiencies higher than 90% for both biofilters, indicating that the addition of GTR did not adversely affect the behavior of the bioreactor. Full removal of n-butyl acetate was obtained for both biofilters. GTR improved the removal of the aromatics in the first part of the biofilter, facilitating lower penetration of the toluene and m-xylene into the bed. A 31-day starvation period was applied and intermittent operation subsequently restarted. In both biofilters, high removal efficiencies after a re-acclimation period of two days were achieved. A shock loading test related to 1-h peaks of three- and four-fold increases in its baseline concentration (0.30 g C m(-3)) was applied in both biofilters. For the biofilter packed with the peat and GTR mixture, attenuation greater than 60% was observed in the maximum outlet concentration when compared to the biofilter packed with peat alone.

Evaluation of a combined activated carbon prefilter and biotrickling filter system treating variable ethanol and ethyl acetate gaseous emissions.

The removal of a 1:1 by weight mixture of ethanol and ethyl acetate was studied in a gas phase biotrickling filter running under conditions that simulated industrial emissions from the flexographic sector, i.e. discontinuous loading (twelve hours per day and five days per week) and oscillating concentration of the inlet stream. Three sets of experimental conditions were tested in which empty‐bed residence time varied from 60 to 25 s (inlet loads from 50 to 90 g C m−3 h−1). The biotrickling filter reached a maximum elimination capacity of 48.5 g C m−3 h−1 (removal efficiency=68.9%) for an empty‐bed residence time of 40 s. A decrease in the residence time from 40 to 25 s adversely affected the elimination capacity (40.3 g C m−3 h−1, removal efficiency=46.6%). For the three tested residence times, outlet concentrations during pollutant feeding were above 100 mg C m−3 (EU legal limit for flexographic facilities). Then an activated carbon prefilter was installed to buffer the fluctuating concentration, enabling a more stable operation. The desorbed pollutant from the activated carbon during non‐feeding hours also served as an extra source of substrate, avoiding severe starvation. The use of the activated carbon prefilter with a volume 25 times lower than that of the bioreactor was shown to reach an average outlet emission concentration lower than 50 mg C m−3 operating the biotrickling filter at an empty‐bed residence time of 40 s, with a maximum elimination capacity of 59.6 g C m−3 h−1 (removal efficiency=92.0%).

Control of VOC emissions from a flexographic printing facility using an industrial biotrickling filter.

The study of an industrial unit of biotrickling filter for the treatment of the exhaust gases of a flexographic facility was investigated over a 2-year period with the objective to meet the volatile organic compound (VOC) regulatory emission limits. Increasing the water flow rate from 2 to 40 m(3) h(-1) improved the performance of the process, meeting the VOC regulation when 40 m(3) h(-1) were used. An empty bed residence time (EBRT) of 36 s was used when the inlet air temperature was 18.7 °C, and an EBRT as low as 26 s was set when the inlet temperature was 26.8 °C. During this long-term operation, the pressure drop over the column of the bioreactor was completely controlled avoiding clogging problems and the system could perfectly handle the non-working periods without VOC emission, demonstrating its robustness and feasibility to treat the emission of the flexographic sector.

Lab-scale Evaluation of Two Biotechnologies to Treat VOC Air Emissions: Comparison with a Pilot Unit Installed in the Plastic Coating Sector

Volatile organic compounds (VOCs) are one of the top five atmospheric pollutants, and, according to an EC directive, are defined as “all organic compounds arising from human activities, other than methane, which are capable of producing photochemical oxidants by reactions with nitrogen oxides in the presence of sunlight” (Council Directive 2001/81/EC). This definition highlights the fact that VOCs play a vital role in the formation of tropospheric ozone, which causes photochemical smog. Short-term exposure to photochemical smog affects respiratory function and has adverse effects on plants (World Health Organization, 2004). The distinction between biogenic and anthropogenic VOCs in the atmosphere is far from straightforward, because many VOC species are produced by both sources (Popescu & Ionel, 2010). Anthropogenic sources of VOCs include air emissions from wastewater treatments plants, motor vehicles, gasoline storage facilities and transportation, dry cleaning and other industrial sources (D.J. Kim & H. Kim, 2005). In this sense, the main sectors involved in non-methane VOC emissions in the EU-27 are solvent and product use (41%), road and non-road transportation (18%), and commercial, institutional, and household associated emissions (14%) (European Environment Agency, 2010). Regarding the industrial sources, Fig. 1 illustrates the contributions from various industrial sectors to EU-27 nonmethane VOC industrial emissions in 2008 (European Pollutant Release and Transfer Register, 2008). The three most important industrial sources are: energy (41%); the chemical industry (22%); and coating and surface treatment activities (18%). In fact, over the past decade, emerging European Union environmental policy has focused on abatement of VOCs from industrial emissions, in an effort to protect environmental and public health. As a result of these initiatives, new European VOC emission limits have been established in the VOC Solvent Emissions Directive (Council Directive 1999/12/EC) for a wide range of industrial sectors. Currently, VOC concentration limits range from 50 to 150 mg C/Nm3, depending on the application and solvent consumption. Although process changes and the substitution of solvent-based products for water-based ones have the potential to minimise VOC emissions, stringent VOC emission limits require