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1.
Biofiltration of waste gases with the fungi Exophiala oligosperma and Paecilomyces variotii 总被引:1,自引:0,他引:1
Two biofilters fed toluene-polluted air were inoculated with new fungal isolates of either Exophiala oligosperma or Paecilomyces variotii, while a third bioreactor was inoculated with a defined consortium composed of both fungi and a co-culture of a Pseudomonas strain and a Bacillus strain. Elimination capacities of 77 g m–3 h–1 and 55 g m–3 h–1 were reached in the fungal biofilters (with removal efficiencies exceeding 99%) in the case of, respectively, E. oligosperma and Paecilomyces variotii when feeding air with a relative humidity (RH) of 85%. The inoculated fungal strains remained the single dominant populations throughout the experiment. Conversely, in the biofilter inoculated with the bacterial–fungal consortium, the bacteria were gradually overgrown by the fungi, reaching a maximum elimination capacity around 77 g m–3 h–1. Determination of carbon dioxide concentrations both in batch assays and in biofiltration studies suggested the near complete mineralization of toluene. The non-linear toluene removal along the height of the biofilters resulted in local elimination capacities of up to 170 g m–3 h–1 and 94 g m–3 h–1 in the reactors inoculated, respectively, with E. oligosperma and P. variotii. Further studies with the most efficient strain, E. oligosperma, showed that the performance was highly dependent on the RH of the air and the pH of the nutrient solution. At a constant 85% RH, the maximum elimination capacity either dropped to 48.7 g m–3 h–1 or increased to 95.6 g m–3 h–1, respectively, when modifying the pH of the nutrient solution from 5.9 to either 4.5 or 7.5. The optimal conditions were 100% RH and pH 7.5, which allowed a maximum elimination capacity of 164.4 g m–3 h–1 under steady-state conditions, with near-complete toluene degradation. 相似文献
2.
Simultaneous removal of benzene, toluene and xylenes mixture by a constructed microbial consortium during biofiltration 总被引:1,自引:0,他引:1
A bacterial consortium with complementary metabolic capabilities was formulated and specific removal rates were 0.14, 0.35, 0.04, and 0.39 h–1 for benzene, toluene, o-xylene, and m,p-xylene, respectively. When immobilized on a porous peat moss biofilter, removal of all five (= BTX) components was observed with rates of 1.8–15.4 g m–3 filter bed h–1. Elimination capacities with respect to the inlet gas concentrations of BTX and airflow rates showed diffusive regimes in the tested concentration range of (0.1–5.3 g m–3) and airflow (0.55–1.82 m3 m–2 h–1) except for o-xylene which reached its critical gas concentration at 0.3 g m–3. 相似文献
3.
After measuring toluene adsorption (15.7 mg-toluene/g-material), water holding capacity (18.5%), organic content (53.8%),
specific surface area (18.1 m2/g-material), and microbial attachment, crab shells were chosen as the main packing material for a biofilter design. The crab
shells, cheap and abundant in the Gangneung area, also have relatively rigid structure, low density, and ability to neutralize
acids generated during mineralization of toluene. Since towel scraps have water holding capacity as high as 301.2%, 10% of
the total packing was supplemented with them to compensate for low water holding capacity of the crab shells. The biofilter
fed with defined chemical medium under 0.8∼1.3 mg/L of inlet toluene concentration and 18 seconds of residence time showed
satisfactory removal efficiency of over 97% and 72.8 g/h·m3 of removal capacity. For the purpose of deceasing operation costs, leaf mold solution was tried as an alternative nutrient
instead of a defined chemical medium. The removal efficiency and removal capacity were 85% and 56.3 g/h·m3, respectively, using the same inlet toluene concentration and residence time. This research shows the possibility of recycling
crab shell waste as packing material for biofilter. In addition, leaf mold was able to serve as an alternative nutrient, which
remarkably decreased the operating cost of the biofilter. 相似文献
4.
The work reported concerns the removal of mixtures of two ketones, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), which find wide application as industrial solvents, from effluent air streams in downward flow biofilters operating at relative humidities in excess of 95 percent. The inlet concentrations of the two pollutants were 300 mg m–3
MEK and 330 mg m–3
MIBK. Maximum elimination capacities achieved were 50 g m–3h–1 for MEK and 20 g m–3h–1 for MIBK. Marked interaction between the elimination of the two ketones was observed and established biophysical models for the kinetic analysis of biofilter operation proved inadequate as far as the complex processes involved in multi-component biodegradable vapour elimination were concerned. The complexity of such systems requires further definition and the development of appropriate models for process evaluation and design. 相似文献
5.
Removal of toluene in waste gases using a biological trickling filter 总被引:12,自引:0,他引:12
The removal of toluene from waste gas was studied in a trickling biofilter. A high level of water recirculation (4.7 m h–1) was maintained in order to keep the liquid phase concentration constant and to achieve a high degree of wetting. For loads in the range from 6 to 150 g m–3 h–1 the maximum volumetric removal rate (elimination capacity) was 35±10 g m–3 h–1, corresponding to a zero order removal rate of 0.11±0.03 g m–2 h–1 per unit of nominal surface area. The surface removal was zero order above the liquid phase concentrations of approximately 1.0 g m–3, corresponding to inlet gas concentrations above 0.7–0.8 g m–3. Below this concentration the surface removal was roughly of first order. The magnitude of the first order surface removal rate constant, k1A
, was estimated to be 0.08–0.27 m h–1 (k1A
a=24–86 h–1). Near-equilibrium conditions existed in the gas effluent, so mass transfer from gas to liquid was obviously relatively fast compared to the biological degradation. An analytical model based on a constant liquid phase concentration through the trickling filter column predicts the effluent gas concentration and the liquid phase concentration for a first and a zero order surface removal. The experimental results were in reasonable agreement with a very simple model valid for conditions with an overall removal governed by the biological degradation and independent of the gas/liquid mass transfer. The overall liquid mass transfer coefficient, KLa, was found to be a factor 6 higher in the system with biofilm compared to the system without. The difference may be explained by: 1. Difference in the wetting of the packing material, 2. Mass transfer occurring directly from the gas phase to the biofilm, and 3. Enlarged contact area between the gas phase and the biofilm due to a rough biofilm surface. 相似文献
6.
The removal of toluene from an experimental gas-stream was studied in an industrial biofilter filled with poplar wood bark. Toluene degradation, approximately 85% through the operating period, resulted in low levels of toluene in the off-gas effluent. For a toluene load of 6.7 g m-3 h-1 the elimination capacity of the biofilter was found to be 6.0 g m-3 h-1. Toluene removal was due to biodegradative activity of microorganisms in the filter bed; the most probable number counts of toluene degraders increased from 2.4×102 to 6.4×107 MPN/g dry packing material in about seven months of air-toluene supply. The degradative capacity of a Burkholderia (Pseudomonas) cepacia strain, isolated from the biofilter material, as an example of the effectiveness of microbial toluence removal was tested in batch culture. The microorganism degraded completely 250 ppm of toluence supplied as sole carbon source in 24 hours. The high performance demonstrated for a long period and the mechanical and physico-chemical stability of the biofilter favour its use in industrial full-scale off-gas control. 相似文献
7.
An innovative, coir-pith-based, filter bed for degrading vapor phase toluene in a gas biofilter over 160 days without any
external nutrient supply is reported in this study. Indigenous microflora present in the coir pith as well as in the aerobic
sludge added at the start-up stage metabolized the toluene, and correspondingly, CO2 was produced in the biofilter. Inlet toluene concentration in the range of 0.75 to 2.63 g/m3 was supplied to the biofilter in short acclimation periods. The maximum elimination capacity achieved was 96.75 g/m3·h at 120.72 g/m3·h loading where around 60% was recovered as CO2. The filter bed maintained a stable low-pressure drop (0–4 mm H2O), neutral pH range (6.5–7.5), and moisture content of 60–80% (w/w) throughout the period. In addition to toluene-degrading microbial community, a grazing fauna including rotifer, bacteriovoric
nematode, tardigrade, and fly larvae were also present in the filter bed. The overall performance of the biofilter bed in
pollutant removal and sustainability was analyzed in this study. 相似文献
8.
The performance of a polyurethane (PU) biofilter inoculated with Rhodococcus sp. EH831 was evaluated under different transient loading conditions, such as shutdown, intermittent and fluctuating loading. A mixture of benzene and toluene vapors was employed as model pollutants. When the biofilter was restarted after a 2 week-shutdown, during which neither clean air nor water was supplied, the benzene and toluene removal capacities were rapidly restored after a re-adaptation period of only 1 day. A comparison of the removal capacity under continuous and intermittent loading revealed that constant and periodic loading (8 h on/16 h off per day) and a 2 day-shutdown did not significantly influence the biofilter performance, although the removals of benzene and toluene were relatively unstable and lower under intermittent loading during the initial week. The result of quantitative real-time PCR showed that Rhodococcus sp. EH831 could be maintained during transient loading periods (1010–1011 CFU/g-dry PU) irrespective of the different operating conditions. 相似文献
9.
Benzene, toluene, ethylbenzene and xylene (BTEX) substrate interactions for a mesophilic (25°C) and thermophilic (50°C) toluene-acclimatized composted pine bark biofilter were investigated. Toluene, benzene, ethylbenzene, o-xylene, m-xylene and p-xylene removal efficiencies, both individually and in paired mixtures with toluene (1:1 ratio), were determined at a total loading rate of 18.1 g m–3 h–1 and retention time ranges of 0.5–3.0 min and 0.6–3.8 min for mesophilic and thermophilic biofilters, respectively. Overall, toluene degradation rates under mesophilic conditions were superior to degradation rates of individual BEX compounds. With the exception of p-xylene, higher removal efficiencies were achieved for individual BEX compounds compared to toluene under thermophilic conditions. Overall BEX compound degradation under mesophilic conditions was ranked as ethylbenzene >benzene >o-xylene >m-xylene >p-xylene. Under thermophilic conditions overall BEX compound degradation was ranked as benzene >o-xylene >ethylbenzene >m-xylene >p-xylene. With the exception of o-xylene, the presence of toluene in paired mixtures with BEX compounds resulted in enhanced removal efficiencies of BEX compounds, under both mesophilic and thermophilic conditions. A substrate interaction index was calculated to compare removal efficiencies at a retention time of 0.8 min (50 s). A reduction in toluene removal efficiencies (negative interaction) in the presence of individual BEX compounds was observed under mesophilic conditions, while enhanced toluene removal efficiency was achieved in the presence of other BEX compounds, with the exception of p-xylene under thermophilic conditions. 相似文献
10.
Peat,zeolite and basalt as adsorbents of ammoniacal nitrogen during manure decomposition 总被引:4,自引:0,他引:4
The effectiveness of sphagnum peat, zeolite (clinoptilonite) and basalt in reducing ammonia losses during aerobic manure decomposition was determined in an incubation experiment. Peat placed in the spent air-stream adsorbed all of the ammonia volatilized during the first 8 days of decomposition, and reduced overall ammonia losses by 59%. Zeolite reduced total ammonia losses by 16%, and basalt by 6%.All adsorbents were considerably less effective in reducing ammonia losses when mixed with the manure. Reductions in ammonia losses of 24% and 1.5% were obtained with the peat and zeolite, respectively. The addition of basalt increased losses.Ammonia and ammonium adsorption isotherms were determined for the three materials. The adsorption capacities and affinity terms of the adsorbents calculated from the isotherms, reflected their ability to reduce ammonia losses in the incubation experiment. Zeolite had both the highest affinity for ammonium and the highest ammonium adsorption capacity. The peat had a very high affinity for ammonia and a high adsorption capacity (23.4 mg NH3–N g–1), whereas zeolite and basalt had a much lower adsorption capacity (1.8 and 0.05 mg NH3–N g–1, respectively) compared with their capacity to adsorb ammonium (18.1 and 0.18 mg NH4–N g–1). 相似文献
11.
Amir Neori Flower E. Msuya Lilach Shauli Andreas Schuenhoff Fidi Kopel Muki Shpigel 《Journal of applied phycology》2003,15(6):543-553
Seaweed biofilters have proven their usefulness in the treatment of fishpond effluents. However, their performance poses a dilemma: TAN (Total Ammonia N) uptake rate – and with it seaweed yield and protein content – is inversely proportional to TAN uptake efficiency. The ideal for a seaweed biofilter performance would be a high uptake rate together with high uptake efficiency. The novel three-stage seaweed biofilter design described here has solved this dilemma. The design used the finding that the performance of seaweed ponds depended on the flux of TAN through them, and that therefore effluents with reduced TAN concentration could provide the seaweed with a high TAN flux if the water flow increased proportionally. Effluents from a seabream fishpond were passed through a series of three successively smaller (25, 12.5 and 6.25 m2, respectively) air-agitated Ulva lactuca ponds. The diminished inflow TAN concentrations to the second and third ponds of the biofilter system were compensated for by the increased water exchange rates, inversely proportional to their sizes. The biofilter performance was evaluated under several TAN loads. TAN was efficiently removed (85–90%), at a high areal rate (up to 2.9 g N m-2 d-1) while producing high protein U. lactuca (up to 44% dw) in all three stages, although with mediocre yields (up to 189 g fresh m-2 d-1). Performance of each seaweed biofilter pond correlated not with TAN concentration, but with areal TAN loads. The novel three-stage design provides significant functional and economic improvements in seaweed biofiltration of intensive fishpond water. 相似文献
12.
Pseudomonas sp. SR-5 was isolated as a styrene-degrading bacterium. In liquid culture containing 1% (v/v) styrene, more than 90% styrene was degraded in 53 h and the doubling time of SR-5 was 2 h. The removal of styrene gas was investigated in biofilters for 31 days using an organic packing material of peat and an inorganic packing material of ceramic inoculated with SR-5. The maximum-styrene-elimination capacities for peat and ceramic packing materials were 236 and 81 g m–3 h–1, respectively. The percentage of styrene converted to low molecular weight compounds including CO2 in the peat and ceramic biofilters during a 10-day operation were estimated to be 90.4 and 36.7%, respectively. As the pressure drop in the peat bioflter at the end of experiment was significantly higher than that in ceramic biofilter, a biofilter using a mixture of peat and ceramic was tested. We determined that the maximum elimination capacity was 170 g m–3 h–1 and the production of low molecular weight compounds was 95% at a low pressure drop for this mixed packing material filter. 相似文献
13.
Prabhat Kumar Thakur Anil Kumar Mathur Shashi Bala Gautam Chandrajit Balomajumder Rahul 《Bioremediation Journal》2013,17(1):61-70
ABSTRACT A laboratory-scale biofilter unit packed with a mixture of compost, sugarcane bagasse, and granulated activated carbon (GAC) in the ratio of 55:30:15 by weight was used for a biofiltration study of air stream containing benzene, toluene, ethylbenzene, and o-xylene (BTEX). The effect of superficial velocity on mass transfer coefficient for the packing was studied by maintaining gas flow rates of 3, 4, 5, 6, and 8 L min?1 for inlet concentrations of 0.1, 0.4, and 0.8 g m?3 for each of benzene, toluene, ethylbenzene, and o-xylene. The maximum elimination capacity was found to be 20.92, 22.72, 20.73, and 18.94 g m?3 h?1 for BTEX, respectively, for stated flow rates. Removal efficiency of BTEX decreased from 99% to 71% for increasing inlet concentration from 0.1 to 0.8 g m?3. Gas film mass transfer coefficient predicted by modified Onda's equation was within ±10% of the experimental values. 相似文献
14.
Development and operation of a trickling biofilter system for continuous treatment of gas-phase trichloroethylene 总被引:3,自引:0,他引:3
A parallel trickling biofilter (TBF) system that consists of two TBFs units in parallel, one for biodegradation of trichloroethylene (TCE) and the other for reactivation of an inactivated biofilm, was developed and operated for continuous treatment of gas-phase TCE by Burkholderia cepacia G4. For inlet loadings below 8.6 mg TCE l–1 d–1, complete removal of TCE was achieved. The maximal TCE elimination capacity was 17 mg l–1 d–1. 相似文献
15.
Microbial response and elimination capacity in biofilters subjected to high toluene loadings 总被引:4,自引:0,他引:4
Elimination capacity (EC) is frequently used as a performance and design criterion for vapor-phase biofilters without further
verification of the microbial quantity and activity. This study was conducted to investigate how biofilters respond to high
pollutant loadings and ultimately how this affects the EC of the biofilter. Two identical laboratory-scale biofilters were
maintained at an initial toluene loading rate of 46 g m−3 h−1 for a period of 24 days. After the initial biofilm development stage, the loading rates were increased to 91 g m−3 h−1 and 137 g m−3 h−1, respectively. Following a short period of pseudo-steady state, toluene removal efficiencies rapidly declined in both biofilters,
with a concurrent decline in both critical and maximum ECs. The decline was mainly due to deterioration in the biodegradation
activity of the biofilm and a decline in the toluene-degrading bacterial population within the biofilm phase. The findings
imply that high toluene loadings accelerated the deterioration in overall performance due to a rapid accumulation of inactive
biomass. As a result, care must be used when relying on EC values for biofilter design and operational purposes, since the
values do not appropriately reflect the temporal changes in biodegradation activity and active biomass quantities that can
occur in biofilters subjected to high inlet loadings. 相似文献
16.
Treatment of H2S using a horizontal biotrickling filter based on biological activated carbon: reactor setup and performance evaluation 总被引:1,自引:0,他引:1
Biological treatment is an emerging and prevalent technology for treating off-gases from wastewater treatment plants. The most commonly reported odorous compound in off-gases is hydrogen sulfide (H2S), which has a very low odor threshold. A self-designed, bench-scale, cross-flow horizontal biotrickling filter (HBF) operated with bacteria immobilized activated carbon (termed biological activated carbon—BAC), was applied for the treatment of H2S. A mixed culture of sulfide-oxidizing bacteria dominated by Acidithiobacillus thiooxidans acclimated from activated sludge was used as bacterial seed and the biofilm was developed by culturing the bacteria in the presence of carbon pellets in mineral medium. HBF performance was evaluated systematically over 120 days, depending on a series of changing factors including inlet H2S concentration, gas retention time (GRT), pH of recirculation solution, upset and recovery, sulfate accumulation, pressure drop, gas-liquid ratio, and shock loading. The biotrickling filter system can operate at high efficiency from the first day of operation. At a volumetric loading of 900 m3 m–3 h–1 (at 92 ppmv H2S inlet concentration), the BAC exhibited maximum elimination capacity (113 g H2S/m–3 h–1) and a removal efficiency of 96% was observed. If the inlet concentration was kept at around 20 ppmv, high H2S removal (over 98%) was achieved at a GRT of 4 s, a value comparable with those currently reported for biotrickling filters. The bacterial population in the acidic biofilter demonstrated capacity for removal of H2S over a broad pH range (pH 1–7). A preliminary investigation into the different effects of bacterial biodegradation and carbon adsorption on system performance was also conducted. This study shows the HBF to be a feasible and economic alternative to physical and chemical treatments for the removal of H2S. 相似文献
17.
Several biofilters and biotrickling filters were used for the treatment of a mixture of formaldehyde and methanol; and their efficiencies were compared. Results obtained with three different inert filter bed materials (lava rock, perlite, activated carbon) suggested that the packing material had only little influence on the performance. The best results were obtained in a biotrickling filter packed with lava rock and fed a nutrient solution that was renewed weekly. A maximum formaldehyde elimination capacity of 180 g m–3 h–1 was reached, while the methanol elimination capacity rose occasionally to more than 600 g m–3 h–1. Formaldehyde degradation was affected by the inlet methanol concentration. Several combinations of load vs empty bed residence time (EBRTs of 71.9, 46.5, 30.0, 20.7 s) were studied, reaching a formaldehyde elimination capacity of 112 g m–3 h–1 with about 80% removal efficiency at the lowest EBRT (20.7 s). 相似文献
18.
The optimal conditions for opening of stomata in detached epidermis of the Crassulacean Acid Metabolism (CAM) plant Kalanchoe daigremontiana were determined. Stomatal opening in CO2–free air was unaffected by light so subsequently all epidermal strips were incubated in the dark and in CO2–free air. Apertures were maximal after 3 h incubation and were significantly greater at 15° C than 25° C. Thus stomata in isolated epidermis of this species can respond directly to temperature. Stomatal opening was greatest when the incubating buffer contained 17.6 mol m–3 K+, but decreased linearly with increasing K+ concentrations between 17.6 and 300 mol m–3; the decrease in aperture was shown to be associated with increasing osmotic potentials of the solutions. Reasons for this behaviour, which differs from that of many C3 and C4 species, are discussed. Stomatal apertures declined linearly upon incubation of epidermis on buffer solutions containing between 10–11 and 10–5 mol m–3 abscisic acid (ABA). Hence stomata on isolated epidermis of K. daigremontiana respond to lower concentrations of ABA than those of any species reported previously. 相似文献
19.
Hee Wook Ryu So Jong Kim Kyung-Suk Cho Tae Ho Lee 《Biotechnology and Bioprocess Engineering》2008,13(3):360-365
In the present study, toluene elimination in the polyurethane (PU) biofilter during long-term (145 day) operation was characterized,
and assessed the effects of changing the inlet loading and space velocity (SV). A very high elimination capacity of 3.7 kg·m−3·h−1 was obtained at an inlet loading of 4.0 kg·m–3·h−1 (inlet toluene concentration of 900 ppmv at a SV of 1,040 h−1). Backwashing with irrigation and compressed air allowed maintenance of a pressure drop of < 80 mm H2O·m−1-filter at an SV of 830 h−1 and an elimination efficiency of > 90% during the 145 day of operation. In conclusion, the PU biofilter can overcome the
problems of clogging caused by excess biomass growth and of low treatment capacities of conventional biofilters. 相似文献
20.
BTEX catabolism interactions in a toluene-acclimatized biofilter 总被引:1,自引:0,他引:1
BTEX substrate interactions for a toluene-acclimatized biofilter consortium were investigated. Benzene, ethylbenzene, o-xylene, m-xylene and p-xylene removal efficiencies were determined at a loading rate of 18.07 g m−3 h−1 and retention times of 0.5–3.0 min. This was also repeated for toluene in a 1:1 (m/m) ratio mixture (toluene: benzene, ethylbenzene,
or xylene ) with each of the other compounds individually to obtain a final total loading of 18.07 g m−3 h−1. The results obtained were modelled using Michaelis–Menten kinetics and an explicit finite difference scheme to generate
v
max and K
m parameters. The v
max/K
m ratio (a measure of the catalytic efficiency, or biodegradation capacity, of the reactor) was used to quantify substrate
interactions occurring within the biofilter reactor without the need for free-cell suspended and monoculture experimentation.
Toluene was found to enhance the catalytic efficiency of the reactor for p-xylene, while catabolism of all the other compounds was inhibited competitively by the presence of toluene. The toluene-acclimatized
biofilter was also able to degrade all of the other BTEX compounds, even in the absence of toluene. The catalytic efficiency
of the reactor for compounds other than toluene was in the order: ethylbenzene>benzene>o-xylene>m-xylene>p-xylene. The catalytic efficiency for toluene was reduced by the presence of all other tested BTEX compounds, with the greatest
inhibitory effect being caused by the presence of benzene, while o-xylene and p-xylene caused the least inhibitory effect. This work illustrated that substrate interactions can be determined directly from
biofilter reactor results without the need for free-cell and monoculture experimentation.
Received: 13 April 2000 / Received revision: 20 July 2000 / Accepted: 27 July 2000 相似文献