A laboratory-scale biotrickling filter (BTF, inner size 14cm ¡Ñ 14cm ¡Ñ 120cmH, packed with fern chips to a height of 100 cm and volume of 19.6 L) was used to test the feasibility of removing odorous compounds emitted from rubber-processing operations. In addition, granule activated carbon (GAC) adsorption and permanganate solution scrubbing were also tested in order to further reduce the odor intensity of vented gas from the BTF. Results indicated that with the operation conditions of EBRT (empty bed retention time) of 20-40 s for the gas through the packed space and VOCs of 5-50 ppm (as methane) for the influent gas to the BTF, approximately 96-97% of ketones (acetone and methyl ethyl ketone) and 50% of toluene and carbon disulfide in the influent gas could be removed. However, there was no significant removal for alkanes by the BTF. The overall VOC and odor removals were both around 80% at an EBRT of 23 s. Performances of GAC adsorption of the residual chemicals in the vented gas from the BTF were better than those of permanganate solution scrubbing. The overall VOC removal by the BTF-GAC system was around 90% and the overall odor (expressed as the dilution to threshold D/T value) removal was even better than that of VOC. A test indicated that D/T were 1303, 733, and 23, respectively, for the influent, BTF effluent, and GAC effluent, and the overall efficiency for the odor removal was 98.2%. It was estimated that the cost is around NT$ 70 for treating 1,000 m3 of the teat gas by the GAC. Efforts should be made by decreasing the cost by other alternative technologies.

Kitchen waste compositing plants emit odorous gas streams with sulfur-, nitrogen-, and oxygen-containing compounds and other hydrocarbons. A pilot-scale biotrickling filter with a space of 0.3 m square and 1.0 m height packed with fern chips was used for removing the odorous components from the kitchen waste compositing gas. An average weight ratio of ¡§kitchen waste: bulking material: seeding compost¡¨ of 90:4.5:5.5 was used to prepare the compositing material for producing the odorous gas for test. The kitchen waste was composed of residual material from food preparation and meal wastes. The bulking material was either wood trimmings or dried leaves and the seeding material was a blend of manure and bird feather compost. Experiments indicate that the composting material could develop to 32-55 oC during a composting period of 6 weeks and the vented gas contained ammonia, amines, mercaptans, and hydrogen sulfide to maximum values of 700, 1,000, 53, and 1.0 ppm, respectively. A maximum odor concentration of 23,000 was obtained and the odor intensity was closely related to mercaptans in the vented gas. Results indicate that by using the bio-treated effluent of the school-owned domestic wastewater treatment plant as a supplemental water and nutrition sources for the biotrickling filter, 0.5-5 and 1-15 ppm of ammonia and amines, respectively, in the introduced odorous gas could completely be removed at conditions of empty-bed-retention-times (EBRT) of 15 s and liquid/gas flow ratio (L/G) of 0.003 m3/m3. Particularly, with an EBRT of 7 s at a fixed L/G of 0.002, 99.7% of odor intensity (dilution to the threshold ratio, DT) in the influent gas with a DT of 5,500 could be removed. Instead of effluent wastewater, by supplementing tap water with 25 mg/L of milk powder to the biotrickling filter, results indicate that with an EBRT of 7 s at a fixed L/G of 0.002, 99.7% of odor intensity in the influent gas with a DT of 13,000 could be removed. Milk powder supplementation gave better performance than the effluent wastewater one.

Abstract This research focuses on the performance of a full-scale biotrickling filter (BTF) for treating a vented gas from an ABS (acrylonitrile-butadiene-styrene) resin plant. The BTF was constructed by reinforced concrete with a size of 5 m in width, 9 m in length, and 3.5 m in height. It consists of six individual chambers with packing materials of 4.6m in length and 4.2m in width for each. The vented gas contains styrene (SM) and acrylonitrile (AN) as two major components and has an average flow rate of 43,000 m3/h (720 m3/min) and a temperature range of 40-53¢J. Three test protocols have been studied to understand the effects of changing scrubbing method, types of packing materials, and amounts of packing materials on the pollutant removal efficacy. Two different instruments (portable FID and laboratory GC) were used to measure the VOC concentrations for both the inlet and outlet of the BTF. Many parameters were monitored for trend analysis, including gas flow rate, empty-bed gas retention time, system temperature, inlet and outlet VOC concentrations, VOC mass flow rate, organic loading, VOC removal efficiency, recirculation water volume, VOC concentration in the recirculation water, and mass flow rate of the recirculation water. These data were analyzed for discussing the technical feasibility of using BTF as an air pollution control unit for petrochemical industry. Experimental results showed that the third protocol using PVC packing materials (installed with 4.6m in length, 4.2 in width, and 0.6m in height for each of the 6 chambers) was the best setup for the target VOC removal. Without adding any special seed and supplementary nutrient, effluent of the wastewater treatment unit of the plant was introduced into the BTF as the recirculation water (pH 7-8.5, volumetric flow rate 15-30 m3/h, and temperature was 35-50¢J). A range of VOC removal efficiencies of 8.6-41% (equivalent to volumetric elimination rates of K = 41-949 g/m3.h) was obtained with loadings of L = 469-3015 g/m3.h based on the GC data. The elimination rates were 41-949 and 27.4-562 g/m3.h, respectively, for AN and SM corresponding to loadings of 121-1104 and 818-1756 g/m3.h for the two components. An average removal efficiency (K/L) of 24.5% was obtained for AN and SM regardless of the magnitude of the loading. Distribution of VOC removal was 13% by biofilms and the rest by the recirculation water. Microbiological tests revealed that Nematods was the most dominating species at high loadings and Trachelophyllum sp. was the most dominating species at lower loadings. It was also estimated that a total operating cost of NT$ 23,920/day is required and that is equivalent to a cost of NT$ 34.1 for eliminating 1 kg of VOCs from the waste gas. The data showed that the VOC loading (469-3015 g/m3.h, average 1808 g/m3.h) to the BTF was much higher than the normal design value of 30-60g/m3.h. It is suggested that a pre-treatment unit should be added into the system to lower the organic loading before the waste stream enters the BTF. In addition, the makeup recirculation water should be increased to foster the bacteria growth and to improve the absorption of VOCs from the waste gas.

The subject of this thesis is divided into two parts: (1) Treatment of 2-ethyl hexanol (2-EH) in an air stream by a pilot-scale biotrickling filter, and (2) Treatment of gaseous VOC emissions from a resin manufacturing plant by a full-scale biotrickling filter. Treatment of 2-Ethyl Hexanol in An Air Stream by A Pilot-Scale Biotrickling Filter 2-Ethyl Hexanol (2-EH) may release from the thermal breakdown of di-isooctyl phthalate (DOP), a commonly-used plasticizer, in the curing stage when manufacturing PVC synthetic leather and gloves. This paper reports the results of studies using a biotrickling filter (BTF) with blast-furnace slag packings (sizes = 2-4 cm and specific surface area = 120 m2/m3) for treatment of 2-EH in an air stream. The experimental setup consisted of a set of two-stage-in-series biotrickling filters. Each stage of the biotrickling filter was constructed from a 19.5-cm x 200-cm (ID x H) acrylic column packed with slags of 125 cm in height. The operation started with the conditions of recirculation liquid pH = 8.0 and rate (VL) = 8.83 m3/m2.h, a steady nutrient (ammonia nitrogen and phosphate phosphorus) addition, and without a special microbial seeding. Results indicate that, yellowish-brown biofilms on the surface of packing slags could be observed in one week and well developed in two weeks after the start-up operation. The effects of volumetric 2-EH loading (L) and superficial gas velocity (U0) on the 2-EH elimination capacity (K) and the removal efficiency (K/L) were tested. Long-term experimental results show that, in the conditions of influent 2-EH concentration C0 = 250 mg/m3, U0 = 162 m3/m2.h, and gas empty-bed-retention time EBRT = 55 s, K/L could be correlated by the equation K/L = 71.9/(72.4+L) with a correlation coefficient (R) of 0.9988. The 2-EH elimination rate was mass-transfer controlled when L<16 g/m3.h and reaction-controlled when L>16 g/m3.h. Results also indicate that nutrient addition and liquid recirculation were important for the normal operation of the BTF in eliminating the influent 2-EH. Treatment of Gaseous VOC Emissions from A Resin-Manufacturing Plant by A Full-Scale Biotrickling Filter A resin and chemical company located in Tainan County, Taiwan engages in the manufacture of PU (poly urethane), PVAC (poly vinyl acetate), PS (poly styrene), and PMMA (poly methyl methacrylate) resins from various chemical stocks. Gaseous volatile organic compounds (VOCs) emitted from the reactors include toluene, methyl ethyl ketone (MEK), acetone, vinyl chloride, styrene, butyl acetate, 2-ethyl hydroxyl acetate, and methyl methacrylate. These VOCs should be properly eliminated before discharging the reactor vents to the atmosphere. This paper reports the performance results of using a biotrickling filter (BTF) with wood packings (sizes = 2-12 cm and specific surface area = 97 m2/m3) for treating the reactor vents with a total flowrate of 80 m3/min at 20-30¢J. The BTF was constructed from a 7.0 m x 6.0 m (ID x H) SUS 304 column with wood packings of 4.0 m in height. The operation started with the conditions of recirculation liquid pH = 7.0-8.0 and rate (VL) = 1.56 m3/m2.h, a steady nutrient (urea and phosphate phosphorus) addition, and without a special microbial seeding. Results indicate that, yellowish-brown biofilms on the surface of packings could be observed in one week and well developed in two weeks after the start-up operation. Long-term operation results show that, in the conditions of influent VOC concentration C0 = 200-10000 ppm (expressed in terms of methane), U0 = 125 m3/m2.h, and gas empty-bed-retention time EBRT = 115 s, K/L could be correlated by the equation K/L = 345/(467+L) with a correlation coefficient (R) of 0.9913. The VOC elimination rate was mass-transfer limited when L<45 g/m3.h, with the mass of VOCs expressed as that of methane. Results also indicate that the liquid recirculation might be interrupted for a hour without influencing the performance. Toluene was the most difficult one to eliminate among the VOCs in the gas stream.

The overall objective of this dissertation work was to optimize the performance of biotrickling filters in reducing emissions of odour and harmful substances from swine facilities. The parameters and operating conditions that have significant impact on the treatment process were identified through a modelling study. Key odour components were selected to serve as model pollutants, which were identified from linear relationships between the logarithm of odour emission and the logarithm of pollutant emission/odour intensity and from odour indices. The potential model pollutants identified were ammonia, dimethyl sulphide, and p-cresol. Different sets of shake-flask experiments were conducted to assess different inocula, to determine the optimum pH, and to estimate the biokinetic parameters for the biodegradation of ammonia and p-cresol. Among the three inocula evaluated, the complex inoculum taken from an existing biotrickling filter showed the best performance in terms of p-cresol and ammonium reduction. The results also showed that the highest p-cresol uptake and reduction rates and NO3- production rate were at pH 7. Moreover, it was found that the biodegradation of p-cresol was better described by the Monod equation (R2 = 0.96) with estimated values of 0.10 h-1 for µm and 103.4 mg L-1 for Ks. The biodegradation of ammonia, on the other hand, was better described by the Haldane equation (R2 = 0.72) with estimated values of 0.17 h-1 for µm, 11.9 mg L-1 for Ks, and 617.9 mg L-1 for Ki. Mass balance equations were formulated to describe the processes occurring in the gas, liquid, and biofilm phases of the treatment system. The differential equations were solved using the finite difference numerical analysis method. A one-at-a-time sensitivity analysis was conducted to identify parameters that have significant impact on ammonia removal. Calibration and validation results showed good agreement between predicted and measured values; based on the fractional bias (FB) results, the normalized model’s prediction errors were within ±1 to 7%. After model calibration and validation, a simulation study was conducted using the model to evaluate the impacts of selected process and design parameters for a biotrickling filter system.

The objectives of this work are related to the kinetic study and characterization of air treatment biofilters with and without percolation which were packed with inert packing materials in order to treat methanol, ethanol and toluene vapours.The thesis is divided into three sections.The first section contains a bibliographic introduction to biofiltration and an experimental study.The review of experimental work shows that methanol, ethanol and toluene can be treated in biofilters with or without percolation. In the experimental study of this section, ethanol is treated in a biotrickling filter at low nitrogen concentrations in the nutrient solution and high removal efficiencies are obtained. In this study, experimental protocols for maintaining the biofilter and controlling the biomass content in the packing bed were developed.The second section is composed of two experimental studies for characterizing biofilters with and without percolation in order to treat methanol. A methodology for calculating the biomass accumulated in the packing bed of a biofilter is among the new experimental protocols developed in this study. In the case of biotrickling filter, methodologies for determining the partition coefficient of methanol and the biomass production rate were developed.The role of the biofilm and the nutrient solution on bioflter performance was also analyzed.The studies of this section lead to a better comprehension of methanol biodegradation in biofilters.The third section contains two kinetic studies for biofilters with and without percolation. In the first study, a new experimental methodology is proposed to calculate microkinetic parameters related to microbial growth in a biofilter. In the second study, the microkinetic and macrokinetic behaviors of methanol and toluene biodegradation are compared.The influence of operating conditions on microbial growth and elimination capacity is also analyzed. This study includes the identification of energy indicators of biofilters with and without percolation, which could be used in energy balances and for estimating the temperature of packing bed.

In this study, a laboratory-scale activated sludge reactor and a biotrickling filter were constructed to study the removal of methyl tert-butyl ether (MTBE) from air vented from contaminated sites. The activated sludge tank (0.4 m¡Ñ0.4 m cross-sectional area, 3.0 m height, and 480 L total volume) was made by acrylic resin. A mixed liquor suspended solids (MLSS) concentration of 2000-3000 mg/L was maintained in the experimental mixed liquor and the sludge was acclimated for 30 days under selected conditions of a Food to Microorganism Ratio (F/M) of 0.3 g BOD/(g MLSS¡Dday) and an influent gas MTBE concentration (C0) of 180 mg/Am3 (@27oC). Results on performance tests show that an average MTBE removal efficiency of 93.6% was obtained with the operation conditions of C0 of 610 mg/Am3 (@27oC), volumetric aeration rate of 0.063 m3/m3¡Dmin, MLSS of 2600 mg/L, and submerged liquid depth of 1.0 m. The biotrickling filter was made by combining two same type of acrylic resin columns (each 0.2 m inner diameter, 2.0 m height, and packed with 900 pieces of polypropylene Pall rings to a height of 1.35 m) in series for the test gas flow and in-parallel for the trickling liquid flow. Each test was operated for 8 hours to reach a steady state for a set of selected conditions (gas flow rate 0.050 m3/min and superficial gas velocity 0.027 m/s, trickling liquid flow rate 0.004 m3/min and pH: 6.8-7.2, and liquid/gas flow ratio: 80 L/m3). Results show that the MTBE removal efficiencies from the influent gas were 40%, 22% and 15%, respectively, with C0 of 50,100 and 230 mg/Am3 (@27oC).

Ammonia, a colorless gas with a characteristic pungent odor, is produced by various industrial and agricultural activities. Emissions of ammonia into the atmosphere not only cause a nuisance in the vicinity of the sources, but also have various environmental effects, such as eutrophication and acidification of terrestrial and aquatic ecosystems, and visibility problems resulting from the formation of aerosols. The traditional treatment of ammonia emissions is based on physical and/or chemical processes, both of which are expensive and produce secondary pollutants. Biological methods are effective and economical for biodegradable odorants and VOC contaminants. This study used fixed-film bioreactors, a biofilter and a biotrickling filter, to remove and oxidize gas-born ammonia. Firstly, a pilot-scale biofilter consisted of two columns (40 cmW ¡Ñ 40 cmL ¡Ñ 70 cmH acrylic column) arranged in series. A medium consisting solely of fern chips, on which biofilms were cultivated, was used as a packing material. The biofilter was tested continuously for 110 days, measuring the removal efficiency, empty bed residence time (EBRT), removal capacity, pressure drop, moisture content and pH. Most of ammonia was eliminated in the first biofiltration column and the removal efficiency increased with the increase in EBRT. Complete removal of the influent ammonia (20-120 ppm) was obtained with an ammonia loading as high as 5.4 g N kg-1 dry media d-1 during the experiment. The Michaelis-Menten equation was tested to be adequate for modeling the ammonia elimination kinetics in the biofilter and the maximum removal rate (Vm) and the half-saturation constant (Ks) were estimated to be 28.2 g N kg-1 dry media d-1 and 129 ppm, respectively. Secondly, a pilot-scale reactor, consisting of a set of two-stage-in-series biotrickling filters, an influent gas supply system and a liquid recirculation system, was utilized to treat ammonia in an air stream. Each stage of the biotrickling filter was constructed from a 20 cm ¡Ñ 200 cm (inner diameter ¡Ñ height) acrylic column packed with cokes (average diameter = 3.0 cm, specific area = 150 m2/m3) of 125 cm height. Experimental results indicate that a time of 30 days is required for development of biofilms for nitrification of the absorbed ammonia from the gas. Long-term (187 days) experimental results show that, in the conditions of EBRT (empty bed gas retention time) = 7.25 s, ¡§circulation liquid/gas¡¨ flow rate ratio = 7.7 L m-3, and liquid pH = 6.65, the level of ammonia in the influent gas was reduced from 230 to 4.0 ppm. With the volumetric ammonia loading of less than 7.37 g NH3-N m-3 hr-1, the system could achieve ammonia removal and nitrification efficiencies of 98 and 94%, respectively, without supplementary glucose as a carbon source. However, with a loading of 13.1 g NH3-N m3 h-1, both decreased gradually due to a lake of carbon source and an accumulation of ammonium and nitrite ions in the recirculation liquid.

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