Two identical bench-scale biotrickling filters （BTFs）, BTF 1 and BTF 2, were evaluated for toluene removal at various gas empty bed contact times （EBCTs） and organic loadings. BTF 1 and BTF 2 were packed with stru...Two identical bench-scale biotrickling filters （BTFs）, BTF 1 and BTF 2, were evaluated for toluene removal at various gas empty bed contact times （EBCTs） and organic loadings. BTF 1 and BTF 2 were packed with structured and cubic synthetic polyurethane sponges, respectively. At a constant toluene loading of 16 g/（m3.hr）, toluene removal efficiencies decreased from 98.8% to 64.3% for BTF 1 and from 98.4% to 74.1% for BTF 2 as gas EBCT decreased from 30 to 5 sec. When the toluene loading increased from 35 to 140 g/（m3.hr） at a gas EBCT of 30 sec, the removal efficiencies decreased from 99.1% to 77.4% for BTF 1 and from 99.0% to 81.5% for BTF 2. The pressure drop for both BTFs increased with increased air flow rate, and did not significantly vary while the toluene loading was increased under similar operation conditions. BTF 1 and BTF 2 could start up successfully within 19 and 27 days, respectively, when packed with fresh sponge media, and the performances could be restored in 3-7 days after biomass was removed and wasted from the media. BTF 2 displayed higher removal efficiency even under shorter EBCT or higher loading rate than BTF1 when other operation conditions were similar, while it showed lower pressure drop than BTF 1 during the whole period of operation. These results demonstrated that both BTFs could treat waste gas containing toluene effectively.展开更多
The effects of Tween-20 and Zn（II） on ethylbenzene removal were evaluated using two biotrickling filters（BTFs）, BTF1 and BTF2. Only BTF1 was fed with Tween-20 and Zn（II）.Results show that ethylbenzene removal de...The effects of Tween-20 and Zn（II） on ethylbenzene removal were evaluated using two biotrickling filters（BTFs）, BTF1 and BTF2. Only BTF1 was fed with Tween-20 and Zn（II）.Results show that ethylbenzene removal decreased from 94% to 69% for BTF1 and from 74%to 54% for BTF2 with increased organic loading from 64.8 to 189.0 g ethylbenzene/（m3·hr） at EBRT of 40 sec. The effect of EBRT（60–15 sec） at a constant ethylbenzene inlet concentration was more significant than that of EBRT（30–10 sec） at a constant organic loading. Biomass accumulation rate within packing media was reduced significantly.展开更多
Dichloromethane is harmful to human health and hazardous to atmospheric environment. In this study, two strains were isolated which were identified as Pseudomonas sp. and Mycobacterium sp., and utilized dichlorometha...Dichloromethane is harmful to human health and hazardous to atmospheric environment. In this study, two strains were isolated which were identified as Pseudomonas sp. and Mycobacterium sp., and utilized dichloromethane （DCM） as sole carbon and energy sources. The optimal culture conditions were temperature of 28℃ and pH of 6.5 for obtaining the two mixed bacterial strains. The investigation on the purification of DCM-contaminated gas was carried out in a bench-scale biotrickling filter which was inoculated with the two strains and operated under these optimal conditions. The DCM removal efficiencies varied between 72% and 99% in the biotrickling filter when empty-bed residence time was 9.6 s with the inlet concentrations ranged fi＇om 0.7 to 3.12 g/m^3 under the conditions ofpH of 6.5 ±0.5 and temperature of 28℃. It was also found that NaCl accumulation in the broth would inhibit the DCM biodegradation dramatically when the accumulated NaCl concentration was over 35.1 g/L.展开更多
The use of a biotrickling filter was investigated for a pilot field-scale elimination of NH3 gas and other odorous gases from a composting plant in Tongzhou District, Beijing. The inlet gas flow rate was 3500 m3/h and...The use of a biotrickling filter was investigated for a pilot field-scale elimination of NH3 gas and other odorous gases from a composting plant in Tongzhou District, Beijing. The inlet gas flow rate was 3500 m3/h and NH3 concentration fluctuated between 2.76–27.84 mg/m3, while the average outlet concentration was 1.06 mg/m3 with an average of 94.9% removal. Critical volumetric loading (removal efficiency=100%) was 11.22 g-N/(m3·h). The odor concentration removal was 86.7%. NH3 removal efficiency decreased as the free ammonia (FA) in the trickling liquid increased. The pressure drop was maintained at about 50 Pa/m and was never more than 55 Pa/m. During the experiment, there was neither backflushing required nor any indication of clogging. Overall, the biotrickling filter was highly efficient and cost-effective for the simultaneous biodegradation of NH3 and other odorous gases from composting, suggesting the possibility of treating odorous gases at the industrial level.展开更多
In the industrial operation of biotrickling filters for hydrogen sulfide(H2S) removal,shock loads or starvation was common due to process variations or equipment malfunctions.In this study,effects of starvation and sh...In the industrial operation of biotrickling filters for hydrogen sulfide(H2S) removal,shock loads or starvation was common due to process variations or equipment malfunctions.In this study,effects of starvation and shock loads on the performance of biotrickling filters for H2S removal were investigated.Four experiments were conducted to evaluate the changes of biomass and viable bacteria numbers in the biotrickling filters during a 24-d starvation.Compared to biomass,viable bacteria numbers decreased significantly during the starvation,especially when airflow was maintained in the absence of spray liquid.During the subsequent re-acclimation,all the bioreactors could resume high removal efficiencies within 4 d regardless of the previous starvation conditions.The results show that the re-acclimation time,in the case of biotrickling filters for H2S removal,is mainly controlled by viable H2S oxidizing bacteria numbers.On the other hand,the biotrickling filters can protect against shock loads in inlet fluctuating H2S concentration after resuming normal operation.When the biotrickling filters were supplied with H2S at an input of lower than 1700 mg/m3,their removal efficiencies were nearly 98% regardless of previous H2S input.展开更多
A laboratory-scale biotrickling filter packed with ceramic lasing rings is built to remove artificial toluene vapor. The performance of biotrickling filter under different superficial gas velocities and inlet toluene ...A laboratory-scale biotrickling filter packed with ceramic lasing rings is built to remove artificial toluene vapor. The performance of biotrickling filter under different superficial gas velocities and inlet toluene concentrations is evaluated. The start-up period is 6 days by using the novel "gas-liquid phase synchronic inoculation" method and adding the optimal components nutrient liquid. The experiments lasts 3 months, and different sets of continuous tests are conducted at an inlet toluene concentration ranging from 30 mg/m3 to 1 223 mg/m3 and at superficial gas velocities ranging from 123 m/h to 370 m/h (corresponding to residence time 9.75-29.3 s). The effect of nutrient liquid recycling rate on biotrickling filter performance is also evaluated. The result shows that the maximum elimination capacity is 152.1 g/(m3*h) at the inlet toluene concentration of 1 223 mg/m3 and the superficial gas velocity of 205 m/h(corresponding to a residence time of 17.6 s). The average toluene removal efficiency reaches 80% in the experiments period, and high water content has a negative effect on biotrickling filter performance. The microscope observation of the micro-organism in the biofilm shows that the Pseudomonas is the dominant group of the mixing microbial culture in the biofilm.展开更多
This study investigated the removal of hydrophobic trichloroethylene（TCE） in the presence of methanol（co-metabolite） in a biotrickling filter,which was seeded with fungi at pH 4.Starvation was chosen as the biomas...This study investigated the removal of hydrophobic trichloroethylene（TCE） in the presence of methanol（co-metabolite） in a biotrickling filter,which was seeded with fungi at pH 4.Starvation was chosen as the biomass control strategy.Two systems,Biofilter I（methanol：TCE 70：30） and Biofilter II（methanol：TCE 80：20） were run in parallel,each with varying composition ratios.The TCE loading rates for both biofilters ranged from 3.22 to 12.88 g/m^3/hr.Depending on the ratio,methanol concentrations varied from 4.08 to 27.95 g/m^3/hr.The performance of the systems was evaluated and compared by calculating removal kinetics,carbon mass balance,efficiencies and elimination capacities.Methanol was observed to enhance TCE removal during the initial loading rate.However,methanol later inhibited TCE degradation above 6.44 g TCE/m^3/hr（Biofilter I） and 3.22 g TCE/m^3/hr（Biofilter II）.Conversely,TCE did not impede methanol removal because over 95% methanol elimination was consistently achieved.Overall,Biofilter I was able to outperform Biofilter II due to its greater resistance towards methanol competition.展开更多
Nitric oxide （NO） is one of the most important air pollutants in atmosphere mainly emitted from combustion source. A biotriclding filter was designed and operated to remove NO from an air stream using bacteria extra...Nitric oxide （NO） is one of the most important air pollutants in atmosphere mainly emitted from combustion source. A biotriclding filter was designed and operated to remove NO from an air stream using bacteria extracted from the sewage sludge of a municipal sewage treatment plant. To obtain the best operation conditions for the biotrickling filter, orthogonal experiments （L9（34）） were designed. Inlet oxygen concentration was found to be the most significant factor of the biotrickling filter and has a significant negative effect on the system. The optimal conditions of the biotrickling filter occurred at a temperature of 40℃, a pH of 8.0 and a chemical oxygen demand of 165 mg/L in the recycled water with no oxygen in the system. The bacteria sample was detected by DNA sequencing technology and showed 93%-98% similarity to Pseudomonas mendocina. Moreover, a full gene sequencing results indicated the bacterium was a brand new strain and named as P. mendocina DLHK. This strain can transfer nitrate to organic nitrogen. The result suggested the assimilation nitrogen process in this system. Through the isotope experimental analysis, two intermediate products （^15NO and ^15N2O） were found. The results indicated the denitrification function and capability of the biotrickling filter in removing NO.展开更多
In this study, methanethiol（MT）-degradation bacteria were cultivated by using MT, methanol and trimethylamine as carbon sources under anaerobic conditions. It was found that the batch bacteria used MT and metha- nol...In this study, methanethiol（MT）-degradation bacteria were cultivated by using MT, methanol and trimethylamine as carbon sources under anaerobic conditions. It was found that the batch bacteria used MT and metha- nol as carbon sources grew faster than those used trimethylamine. The enriched bacteria used MT and methanol as the carbon sources were respectively inoculated in different biotrickling filters. The biological conversion performance ot MT under anaerobic conditions was investigated in biotrickling filters. The results showed that the performance of the biotrickling filter inoculated with the bacteria enriched using MT was better than that inoculated with the bacteria en- riched using methanol. When the inlet concentration of MT was 0.005vo1% （50 ppm）, the empty bed residence time was 50 s, pH value was 8.0, and the flow rate of the nutrient solution was 10 L/h, the removal efficiency of MT reached 95.3%. Adding methanol stimulated the growth of the biomass and the degradation of MT, but caused that some bacteria only degrading methanol outcompeted the bacteria only degrading MT. The concentration of sodium bicarbonate in the nutrient solution needed to be controlled lower than 30 g/L, otherwise, it would be harmful to the degradation of MT.展开更多
A biotrickling filter packed with the regular ceramic spheres was designed and fabricated to purify the low toluene-concentration waste gas.Particular attention was made to the study of the start-up behavior of the bi...A biotrickling filter packed with the regular ceramic spheres was designed and fabricated to purify the low toluene-concentration waste gas.Particular attention was made to the study of the start-up behavior of the biotrickling filter.Moreover,the steady performances were investigated to establish the experimental correlation between the operation factors and removal efficiency.It was found that the start-up process of the biotrickling filter exhibited three stages including the biofilm formation,biofilm development,and biofilm stabilization.The OD600 nm of the circulated liquid,gas pressure drop,elimination capacity,and temperature rise maintained at a rather low level in the biofilm formation stage,then increased rapidly in the biofilm development stage,and finally reached a stable value in the biofilm stabilization stage.It was also found that the removal efficiency of the biotrickling filter in the stable period decreased with increase in the waste gas flow rate,circulated liquid flow rate,and diameter of the ceramic sphere.More interestingly,it was revealed the operation modes have a significant influence on the removal efficiency of the biotrickling filter,and the microorganism show a high activity under the operating temperature ranging from 30°C to 40°C.The experimental correlations for describing the effect of operation factors on the removal efficiency of the biotrickling filters under both the co-current and counter-current operation modes were obtained.The correlation results are in good agreement with the experimental data.展开更多
Biotrickling filters(BTFs) for hydrophobic chlorobenzene(CB) purification are limited by mass transfer and biodegradation. The CB mass transfer rate could be improved by 150 mg/L rhamnolipids. This study evaluated the...Biotrickling filters(BTFs) for hydrophobic chlorobenzene(CB) purification are limited by mass transfer and biodegradation. The CB mass transfer rate could be improved by 150 mg/L rhamnolipids. This study evaluated the combined use of Fe^(3+) and Zn^(2+) to enhance biodegradation in a BTF over 35 day. The effects of these trace elements were analysed under different inlet concentrations(250, 600, 900, and 1200 mg/L) and empty bed residence times(EBRTs;60, 45, and 32 sec). Batch experiments showed that the promoting effects of Fe^(3+)/Zn^(2+) on microbial growth and metabolism were highest for 3 mg/L Fe^(3+) and 2 mg/L Zn^(2+), followed by 2 mg/L Zn^(2+), and lowest at 3 mg/L Fe^(3+). Compared to BTF in the absence of Fe^(3+) and Zn^(2+), the average CB elimination capacity and removal efficiency in the presence of Fe^(3+) and Zn^(2+) increased from 61.54 to 65.79 g/(m 3 hr) and from 80.93% to 89.37%, respectively, at an EBRT of 60 sec. The average removal efficiency at EBRTs of 60, 45, and 32 sec increased by 2.89%, 5.63%, and 11.61%, respectively. The chemical composition(proteins(PN), polysaccharides(PS)) and functional groups of the biofilm were analysed at 60, 81, and 95 day. Fe^(3+) and Zn^(2+) significantly enhanced PN and PS secretion, which may have promoted CB adsorption and biodegradation. High-throughput sequencing revealed the promoting effect of Fe^(3+) and Zn^(2+) on bacterial populations. The combination of Fe^(3+) and Zn^(2+) with rhamnolipids was an efficient method for improving CB biodegradation in BTFs.展开更多
Geological materials,both natural and processed, such as volcanics and ceramics(made of clay),has qualities such as positive charge on the surface,strong hydrophilicity,high specific surface area,high porosity,which a...Geological materials,both natural and processed, such as volcanics and ceramics(made of clay),has qualities such as positive charge on the surface,strong hydrophilicity,high specific surface area,high porosity,which are in favor of not only microorganism contacting and forming biofilm,but also the oxygen enrichment as well as the mass transfer process of nutriment and garbage produced by metabolism.展开更多
基金supported by the National Natural Science Foundation of China (No. 50778066)the National Science and Technology Support Program of China (No. 2006BAJ04A13)the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20090161110010)
文摘Two identical bench-scale biotrickling filters （BTFs）, BTF 1 and BTF 2, were evaluated for toluene removal at various gas empty bed contact times （EBCTs） and organic loadings. BTF 1 and BTF 2 were packed with structured and cubic synthetic polyurethane sponges, respectively. At a constant toluene loading of 16 g/（m3.hr）, toluene removal efficiencies decreased from 98.8% to 64.3% for BTF 1 and from 98.4% to 74.1% for BTF 2 as gas EBCT decreased from 30 to 5 sec. When the toluene loading increased from 35 to 140 g/（m3.hr） at a gas EBCT of 30 sec, the removal efficiencies decreased from 99.1% to 77.4% for BTF 1 and from 99.0% to 81.5% for BTF 2. The pressure drop for both BTFs increased with increased air flow rate, and did not significantly vary while the toluene loading was increased under similar operation conditions. BTF 1 and BTF 2 could start up successfully within 19 and 27 days, respectively, when packed with fresh sponge media, and the performances could be restored in 3-7 days after biomass was removed and wasted from the media. BTF 2 displayed higher removal efficiency even under shorter EBCT or higher loading rate than BTF1 when other operation conditions were similar, while it showed lower pressure drop than BTF 1 during the whole period of operation. These results demonstrated that both BTFs could treat waste gas containing toluene effectively.
基金support by the National Natural Science Foundation of China(No.51278464,41301327)
文摘The effects of Tween-20 and Zn（II） on ethylbenzene removal were evaluated using two biotrickling filters（BTFs）, BTF1 and BTF2. Only BTF1 was fed with Tween-20 and Zn（II）.Results show that ethylbenzene removal decreased from 94% to 69% for BTF1 and from 74%to 54% for BTF2 with increased organic loading from 64.8 to 189.0 g ethylbenzene/（m3·hr） at EBRT of 40 sec. The effect of EBRT（60–15 sec） at a constant ethylbenzene inlet concentration was more significant than that of EBRT（30–10 sec） at a constant organic loading. Biomass accumulation rate within packing media was reduced significantly.
基金The National Natural Science Foundation of China (No. 20476099)
文摘Dichloromethane is harmful to human health and hazardous to atmospheric environment. In this study, two strains were isolated which were identified as Pseudomonas sp. and Mycobacterium sp., and utilized dichloromethane （DCM） as sole carbon and energy sources. The optimal culture conditions were temperature of 28℃ and pH of 6.5 for obtaining the two mixed bacterial strains. The investigation on the purification of DCM-contaminated gas was carried out in a bench-scale biotrickling filter which was inoculated with the two strains and operated under these optimal conditions. The DCM removal efficiencies varied between 72% and 99% in the biotrickling filter when empty-bed residence time was 9.6 s with the inlet concentrations ranged fi＇om 0.7 to 3.12 g/m^3 under the conditions ofpH of 6.5 ±0.5 and temperature of 28℃. It was also found that NaCl accumulation in the broth would inhibit the DCM biodegradation dramatically when the accumulated NaCl concentration was over 35.1 g/L.
基金Project supported by the National Natural Science and Technology Pillar Program in the Eleventh Five-year Plan Period (No. 2006BAJ04A06)the Special Item of System Reformation of the Beijing Municipal Science and Technology Commission, China
文摘The use of a biotrickling filter was investigated for a pilot field-scale elimination of NH3 gas and other odorous gases from a composting plant in Tongzhou District, Beijing. The inlet gas flow rate was 3500 m3/h and NH3 concentration fluctuated between 2.76–27.84 mg/m3, while the average outlet concentration was 1.06 mg/m3 with an average of 94.9% removal. Critical volumetric loading (removal efficiency=100%) was 11.22 g-N/(m3·h). The odor concentration removal was 86.7%. NH3 removal efficiency decreased as the free ammonia (FA) in the trickling liquid increased. The pressure drop was maintained at about 50 Pa/m and was never more than 55 Pa/m. During the experiment, there was neither backflushing required nor any indication of clogging. Overall, the biotrickling filter was highly efficient and cost-effective for the simultaneous biodegradation of NH3 and other odorous gases from composting, suggesting the possibility of treating odorous gases at the industrial level.
基金supported by the Foundation for Society Development of Jilin Province (No.20080412-1)the Education Research Foundation for Science and Technology Development of Jilin Provincethe Foundation for Doctor Research in Northeast Dianli University of Jilin Province (No.BSJXM-200710),China
文摘In the industrial operation of biotrickling filters for hydrogen sulfide(H2S) removal,shock loads or starvation was common due to process variations or equipment malfunctions.In this study,effects of starvation and shock loads on the performance of biotrickling filters for H2S removal were investigated.Four experiments were conducted to evaluate the changes of biomass and viable bacteria numbers in the biotrickling filters during a 24-d starvation.Compared to biomass,viable bacteria numbers decreased significantly during the starvation,especially when airflow was maintained in the absence of spray liquid.During the subsequent re-acclimation,all the bioreactors could resume high removal efficiencies within 4 d regardless of the previous starvation conditions.The results show that the re-acclimation time,in the case of biotrickling filters for H2S removal,is mainly controlled by viable H2S oxidizing bacteria numbers.On the other hand,the biotrickling filters can protect against shock loads in inlet fluctuating H2S concentration after resuming normal operation.When the biotrickling filters were supplied with H2S at an input of lower than 1700 mg/m3,their removal efficiencies were nearly 98% regardless of previous H2S input.
文摘A laboratory-scale biotrickling filter packed with ceramic lasing rings is built to remove artificial toluene vapor. The performance of biotrickling filter under different superficial gas velocities and inlet toluene concentrations is evaluated. The start-up period is 6 days by using the novel "gas-liquid phase synchronic inoculation" method and adding the optimal components nutrient liquid. The experiments lasts 3 months, and different sets of continuous tests are conducted at an inlet toluene concentration ranging from 30 mg/m3 to 1 223 mg/m3 and at superficial gas velocities ranging from 123 m/h to 370 m/h (corresponding to residence time 9.75-29.3 s). The effect of nutrient liquid recycling rate on biotrickling filter performance is also evaluated. The result shows that the maximum elimination capacity is 152.1 g/(m3*h) at the inlet toluene concentration of 1 223 mg/m3 and the superficial gas velocity of 205 m/h(corresponding to a residence time of 17.6 s). The average toluene removal efficiency reaches 80% in the experiments period, and high water content has a negative effect on biotrickling filter performance. The microscope observation of the micro-organism in the biofilm shows that the Pseudomonas is the dominant group of the mixing microbial culture in the biofilm.
文摘This study investigated the removal of hydrophobic trichloroethylene（TCE） in the presence of methanol（co-metabolite） in a biotrickling filter,which was seeded with fungi at pH 4.Starvation was chosen as the biomass control strategy.Two systems,Biofilter I（methanol：TCE 70：30） and Biofilter II（methanol：TCE 80：20） were run in parallel,each with varying composition ratios.The TCE loading rates for both biofilters ranged from 3.22 to 12.88 g/m^3/hr.Depending on the ratio,methanol concentrations varied from 4.08 to 27.95 g/m^3/hr.The performance of the systems was evaluated and compared by calculating removal kinetics,carbon mass balance,efficiencies and elimination capacities.Methanol was observed to enhance TCE removal during the initial loading rate.However,methanol later inhibited TCE degradation above 6.44 g TCE/m^3/hr（Biofilter I） and 3.22 g TCE/m^3/hr（Biofilter II）.Conversely,TCE did not impede methanol removal because over 95% methanol elimination was consistently achieved.Overall,Biofilter I was able to outperform Biofilter II due to its greater resistance towards methanol competition.
基金supported by the Committee for Research and Conference Grants grant of the University of Hong Kong(200907176087)
文摘Nitric oxide （NO） is one of the most important air pollutants in atmosphere mainly emitted from combustion source. A biotriclding filter was designed and operated to remove NO from an air stream using bacteria extracted from the sewage sludge of a municipal sewage treatment plant. To obtain the best operation conditions for the biotrickling filter, orthogonal experiments （L9（34）） were designed. Inlet oxygen concentration was found to be the most significant factor of the biotrickling filter and has a significant negative effect on the system. The optimal conditions of the biotrickling filter occurred at a temperature of 40℃, a pH of 8.0 and a chemical oxygen demand of 165 mg/L in the recycled water with no oxygen in the system. The bacteria sample was detected by DNA sequencing technology and showed 93%-98% similarity to Pseudomonas mendocina. Moreover, a full gene sequencing results indicated the bacterium was a brand new strain and named as P. mendocina DLHK. This strain can transfer nitrate to organic nitrogen. The result suggested the assimilation nitrogen process in this system. Through the isotope experimental analysis, two intermediate products （^15NO and ^15N2O） were found. The results indicated the denitrification function and capability of the biotrickling filter in removing NO.
基金Supported by the National Natural Science Foundation of China(No.21106098)
文摘In this study, methanethiol（MT）-degradation bacteria were cultivated by using MT, methanol and trimethylamine as carbon sources under anaerobic conditions. It was found that the batch bacteria used MT and metha- nol as carbon sources grew faster than those used trimethylamine. The enriched bacteria used MT and methanol as the carbon sources were respectively inoculated in different biotrickling filters. The biological conversion performance ot MT under anaerobic conditions was investigated in biotrickling filters. The results showed that the performance of the biotrickling filter inoculated with the bacteria enriched using MT was better than that inoculated with the bacteria en- riched using methanol. When the inlet concentration of MT was 0.005vo1% （50 ppm）, the empty bed residence time was 50 s, pH value was 8.0, and the flow rate of the nutrient solution was 10 L/h, the removal efficiency of MT reached 95.3%. Adding methanol stimulated the growth of the biomass and the degradation of MT, but caused that some bacteria only degrading methanol outcompeted the bacteria only degrading MT. The concentration of sodium bicarbonate in the nutrient solution needed to be controlled lower than 30 g/L, otherwise, it would be harmful to the degradation of MT.
基金supported by the National Natural Science Foundation of China(Grant No.50806086)the National Science Fund of China for Distinguished Young Scholars(Grant No.50825602)
文摘A biotrickling filter packed with the regular ceramic spheres was designed and fabricated to purify the low toluene-concentration waste gas.Particular attention was made to the study of the start-up behavior of the biotrickling filter.Moreover,the steady performances were investigated to establish the experimental correlation between the operation factors and removal efficiency.It was found that the start-up process of the biotrickling filter exhibited three stages including the biofilm formation,biofilm development,and biofilm stabilization.The OD600 nm of the circulated liquid,gas pressure drop,elimination capacity,and temperature rise maintained at a rather low level in the biofilm formation stage,then increased rapidly in the biofilm development stage,and finally reached a stable value in the biofilm stabilization stage.It was also found that the removal efficiency of the biotrickling filter in the stable period decreased with increase in the waste gas flow rate,circulated liquid flow rate,and diameter of the ceramic sphere.More interestingly,it was revealed the operation modes have a significant influence on the removal efficiency of the biotrickling filter,and the microorganism show a high activity under the operating temperature ranging from 30°C to 40°C.The experimental correlations for describing the effect of operation factors on the removal efficiency of the biotrickling filters under both the co-current and counter-current operation modes were obtained.The correlation results are in good agreement with the experimental data.
基金supported by the Fundamental Research Funds for the Central Universities(No.2018XKQYMS12)the Program for the National Natural Science Foundation of China(Nos.51778612 and 51974314)the Natural Science Foundation of Jiangsu Province(No.BK20191480)。
文摘Biotrickling filters(BTFs) for hydrophobic chlorobenzene(CB) purification are limited by mass transfer and biodegradation. The CB mass transfer rate could be improved by 150 mg/L rhamnolipids. This study evaluated the combined use of Fe^(3+) and Zn^(2+) to enhance biodegradation in a BTF over 35 day. The effects of these trace elements were analysed under different inlet concentrations(250, 600, 900, and 1200 mg/L) and empty bed residence times(EBRTs;60, 45, and 32 sec). Batch experiments showed that the promoting effects of Fe^(3+)/Zn^(2+) on microbial growth and metabolism were highest for 3 mg/L Fe^(3+) and 2 mg/L Zn^(2+), followed by 2 mg/L Zn^(2+), and lowest at 3 mg/L Fe^(3+). Compared to BTF in the absence of Fe^(3+) and Zn^(2+), the average CB elimination capacity and removal efficiency in the presence of Fe^(3+) and Zn^(2+) increased from 61.54 to 65.79 g/(m 3 hr) and from 80.93% to 89.37%, respectively, at an EBRT of 60 sec. The average removal efficiency at EBRTs of 60, 45, and 32 sec increased by 2.89%, 5.63%, and 11.61%, respectively. The chemical composition(proteins(PN), polysaccharides(PS)) and functional groups of the biofilm were analysed at 60, 81, and 95 day. Fe^(3+) and Zn^(2+) significantly enhanced PN and PS secretion, which may have promoted CB adsorption and biodegradation. High-throughput sequencing revealed the promoting effect of Fe^(3+) and Zn^(2+) on bacterial populations. The combination of Fe^(3+) and Zn^(2+) with rhamnolipids was an efficient method for improving CB biodegradation in BTFs.
文摘Geological materials,both natural and processed, such as volcanics and ceramics(made of clay),has qualities such as positive charge on the surface,strong hydrophilicity,high specific surface area,high porosity,which are in favor of not only microorganism contacting and forming biofilm,but also the oxygen enrichment as well as the mass transfer process of nutriment and garbage produced by metabolism.
