多层生物滤塔净化硫化氢废气研究

以木屑为填料,采用多层生物滤塔净化H2S气体,研究其适宜的工艺条件及生物降解宏观动力学.结果表明,填料分层可提高H2S去除率,当进气容积负荷＜153.2 g H2S/(m3·d)时,H2S的去除率保持在90%以上;进气浓度低于70 mg/m3,下层200mm填料对H2S总去除率的贡献在50%以上;填料含水率为50%～6...     

改进型生物滴滤塔处理H2S臭气的最适工艺条件研究

以H2S气体为研究对象,考察改进型生物滴滤塔的脱臭效能、最适工艺运行条件及其影响因素.试验结果表明,循环液喷淋量为10 L/s,气体流量为400 L/s的情况下,最高H2S负荷率可以达到68.2 g/m3·h;最适气体停留时间68.4 s.当入口H2S浓度分别为0～700 mg/m3、700～1000 mg/m3和大于1000 mg/m3时,对应的最适循环液喷淋量为10 L/s、15 L/s和60 L/s.H2S去除率100%的情况下,最大允许进气浓度可达1870 mg/m3,即最大H2S负荷率为98.4 g/m3·h.该研究表明,改进型生物滴滤塔具有较高的H2S去除能力,最适工艺运行条件的确定对污水厂臭气和化工行业产生的H2S处理具有一定的指导意义.     

生物滴滤塔处理H_2S臭气

目前,环保政策极其关注污水处理厂的臭气排放并制定了排放标准。本实验依托3个并联的中试生物滴滤塔对污水提升泵站的H2S臭气展开研究,考察不同H2S进气负荷、停留时间、压降和填料填装方式(竹炭-陶粒分层填装、完全混合及全竹炭填装)等因素对H2S去除率的影响。对生物滴滤塔的出气浓度、滤出液p H、SO2-4离子等进行测试分析,建立传质、降解动力学模型,并分析。在停留时间为25 s连续进气条件下,考察进气负荷在0.59~5.00 g H2S/(m3·h)范围内生物滴滤塔对H2S臭气的去除表现效果。研究结果表明,各生物滴滤塔的去除率(RE)都维持在98%以上,而且出气浓度达到厂界废气排放三级标准;相较于完全混合填装方式,分层填装在去除H2S臭气时略显优势。采用Michaelis-Menten方程描述生物滴滤塔的去除表现,表观半饱和常数Ks和最大表观去除速率Vm分别为5.92 m L/m3和5.84 g H2S/(m3·h)。     

一种缺氧型生物滴滤塔对硫化氢去除的最佳反应条件

取自污水处理厂二沉池活性污泥载入生物滴滤塔中,与传统生物滴滤塔对比,考察了在缺氧条件下微生物对H2S的去除效率,最适工艺运行条件及影响因素,实验结果表明,最佳工艺运行条件:温度为30℃,pH 6.0,H2S入口浓度C1=1 000 mg/m3、C2=2 000 mg/m3、C3=3 000 mg/m3,对应的最适气体流量和循环液喷淋量分别为35～55 L/h、45 L/h、55L/h和20 L/h、40 L/h、50 L/h,该生物滴滤塔最高H2S负荷率可达6.9 g/(m3.h),具有较高的H2S去除效率,最适工艺运行条件的确定对实际大中型沼气发酵池净化配套系统具有一定的指导意义。     

铁氧化物多孔陶粒生物滴滤塔净化硫化氢气体

采用装有凹凸棒石基铁氧化物多孔陶粒作为填料的生物滴滤塔,进行了长期实验室H2S脱臭实验。结果表明,该生物滴滤塔H2S的进气浓度低于500 mg/m3时,循环营养液喷淋量高于1.5 L/h,气体最佳停留时间为54.9 s,去除率在95%以上。代谢产物以SO2-4为主,转化速率在52.42 g/(m3·d)左右。该滴滤塔系统可稳定而有效运行。生物相观察表明,滴滤塔填料表面附着大量微生物,铁氧化物陶粒具有化学和生物惰性,有利于微生物的附着。     

不同挂膜方式生物滴滤塔处理含H2S恶臭气体简

采用菌剂挂膜，活性污泥挂膜和自然挂膜3种不同方式形成生物滴滤塔，考察挂膜方式对生物滴滤塔去除H₂S恶臭气体的影响。结果表明，当进气H₂S浓度为5 mg/m³时，菌剂挂膜、活性污泥挂膜、自然挂膜形成的生物滴滤塔出气H₂S浓度分别为15.7~17.4、11.6~14.8和15.0~15.9 μg/m³；塔内压降分别为3~4 mm水柱、6 mm水柱和4~5 mm水柱；喷淋后滤出液中硫酸根的浓度分别为14、22和17 mg/L，硫的转化率分别为45%、60%和50%。当进气H₂S浓度增大至7 mg/m³时，3个塔经过7 d的调整后，均能达到稳定状态，稳定后3个塔中出气H₂S浓度和压降基本没变，喷淋后滤出液中硫酸根浓度依次增大至25、31和30 mg/L左右。采用活性污泥挂膜形成的生物滴滤塔处理H₂S的能力比菌剂挂膜和自然挂膜的高。     

高效苯降解菌的筛选鉴定及其在生物过滤塔处理苯的填料选择

从污水处理厂曝气池的活性污泥筛选出1株苯的高效降解真菌HD-3,经形态特征、ITS基因序列系统学分析,确定HD-3为杂色曲霉Aspergillus versicolor,该菌株8 d内对初始浓度439.3 mg/L和4 393 mg/L的苯的降解率分别为78.56%和33.96%。当苯的初始浓度为439.3 mg/L,HD-3降解苯的最适温度为30℃,最适pH为4.5。在此基础上,提出了采用不同填料生物过滤塔处理苯废气的工艺,并进行了实验研究,实验结果表明:(1)随着苯的浓度提高,苯的降解率逐渐降低。当苯的浓度为200 mg/m3时,煤质柱状活性炭生物过滤塔、生物陶粒生物过滤塔、竹材生物过滤塔的苯平均去除率(REave)分别为93.63%、93.16%和82.38%;当苯的进口浓度增加到3 000 mg/m3时,3种生物过滤塔的苯平均去除率(REave)分别为78.89%、68.43%和51.87%。(2)不同填料对苯的去除能力不同,煤质柱状活性炭>生物陶粒>竹材。     

不同挂膜方式生物滴滤塔处理含H2S恶臭气体

采用菌剂挂膜，活性污泥挂膜和自然挂膜3种不同方式形成生物滴滤塔，考察挂膜方式对生物滴滤塔去除H2s恶臭气体的影响。结果表明，当进气H2S浓度为5mg／m3时，菌剂挂膜、活性污泥挂膜、自然挂膜形成的生物滴滤塔出气H2s浓度分别为15．7～17．4、11．6～14．8和15．0～15．9μg／m3；塔内压降分别为3—4mm水柱、6mm水柱和4—5mm水柱；喷淋后滤出液中硫酸根的浓度分别为14、22和17mg／L，硫的转化率分别为45％、60％和50％。当进气H2S浓度增大至7mg／m3时，3个塔经过7d的调整后，均能达到稳定状态，稳定后3个塔中出气H2s浓度和压降基本没变，喷淋后滤出液中硫酸根浓度依次增大至25、31和30mg／L左右。采用活性污泥挂膜形成的生物滴滤塔处理H2s的能力比菌剂挂膜和自然挂膜的高。     

生物过滤塔处理实验室废气

研究了生物过滤塔处理实验室排放的模拟混合废气,考察了反应器对苯、甲苯、二甲苯、乙醇、丙酮、乙酸乙酯和甲烷等废气的去除效果。运行结果表明,在设备稳定运行期间,进气中总挥发性有机物(TVOCs)的浓度为124～380 mg/m3,而出气浓度在10～40 mg/m3,去除效率保持在85%以上。实验室废气中的多种污染物在生物过滤塔中去除机理不同,亲水性污染物的去除效率高于疏水性污染物。通过系统关停后重启,污染物的去除效果在第2天就能恢复,这为生物过滤塔处理实验室废气过程的停运检修或者系统闲置提供了可行性。     

生物滤塔-人工湿地组合工艺对农村生活污水净化效果研究

采用厌氧/射流充氧生物滤塔/人工湿地组合工艺处理农村生活污水,考察了组合工艺及其各处理单元对污染物去除的贡献率。在实验室进行了小试,实验结果表明：该组合工艺对污染物具有较好的去除效果,在稳定工况下,组合工艺对COD、NH4＋-N、TN和TP的平均去除率分别为85.4%、74.5%、75.9%和78.3%。生物滤塔能有效...     

Biological elimination of H2S and NH3 from wastegases by biofilter packed with immobilized heterotrophic bacteria

Biotreatment of various ratios of H₂S and NH₃ gas mixtures was studied using the biofilters, packed with co-immobilized cells (Arthrobacter oxydans CH8 for NH₃ and Pseudomonas putida CH11 for H₂S). Extensive tests to determine removal characteristics, removal efficiency, removal kinetics, and pressure drops of the biofilters were performed. To estimate the largest allowable inlet concentration, a prediction model was also employed. Greater than 95% and 90% removal efficiencies were observed for NH₃ and H₂S, respectively, irrespective of the ratios of H₂S and NH₃ gas mixtures. The results showed that H₂S removal of the biofilter was significantly affected by high inlet concentrations of H₂S and NH₃. As high H₂S concentration was an inhibitory substrate for the growth of heterotrophic sulfur-oxidizing bacteria, the activity of H₂S oxidation was thus inhibited. In the case of high NH₃ concentration, the poor H₂S removal efficiency might be attributed to the acidification of the biofilter. The phenomenon was caused by acidic metabolite accumulation of NH₃. Through kinetic analysis, the presence of NH₃ did not hinder the NH₃ removal, but a high H₂S concentration would result in low removal efficiency. Conversely, H₂S of adequate concentrations would favor the removal of incoming NH₃. The results also indicated that maximum inlet concentrations (model-estimated) agreed well with the experimental values for space velocities of 50–150 h⁻¹. Hence, the results would be used as the guideline for the design and operation of biofilters.     

Carbon Disulfide and Hydrogen Sulfide Removal with a Peat Biofilter

ABSTRACT

Simultaneous removal of H₂S and CS₂ was studied with a peat biofilter inoculated with a Thiobacillus strain that oxidizes both compounds in an acidic environment. Both sulfurous gases at concentrations below 600 mg S/m³ were efficiently removed, and the removal efficiencies were similar, 99%, with an empty bed retention time (EBRT) of more than 60 sec. Concentrations greater than 1300-5000 mg S/m³ caused overloading of the filter material, resulting in high H₂SO₄ production, accumulation of elemental sulfur, and reduced removal efficiency. The highest sulfur removal rate achieved was 4500 g-S/day/m³ filter material. These results indicate that peat is suitable as a biofilter material for the removal of a mixture of H₂S and CS₂ when concentrations of gases to be purified are low (less than 600 mg/m³), but it is still odorous and toxic to the environment and humans.     

Operational Characteristics of Effective Removal of H2S and NH3 Waste Gases by Activated Carbon Biofilter

Abstract

Simultaneous removal of hydrogen sulfide (H₂S) and am- gases. monia (NH₃) gases from gaseous streams was studied in a biofilter packed with granule activated carbon. Extensive studies, including the effects of carbon (C) source on the growth of inoculated microorganisms and gas removal efficiency, product analysis, bioaerosol emission, pressure drop, and cost evaluation, were conducted. The results indicated that molasses was a potential C source for inoculated cell growth that resulted in removal efficiencies of 99.5% for H₂S and 99.2% for NH₃. Microbial community observation by scanning electron microscopy indicated that granule activated carbon was an excellent support for microorganism attachment for long-term waste gas treatment. No disintegration or breakdown of biofilm was found when the system was operated for 140 days. The low bioaerosol concentration emitted from the biofilter showed that the system effectively avoided the environmental risk of bioaerosol emission. Also, the system is suitable to apply in the field because of its low pressure drop and treatment cost. Because NH₃ gas was mainly converted to organic nitrogen, and H₂S gas was converted to elemental sulfur, no acidification or alkalinity phenomena were found because of the metabolite products. Thus, the results of this study demonstrate that the biofilter is a feasible bioreactor in the removal of waste gases.     

Comments on “Relating Summer Ambient Particulate Sulfur,Sulfur Dioxide,and Light Scattering to Gaseous Tracer Emissions from the MOHAVE Power Project”

ABSTRACT

A trickle bed air biofilter (TBAB) was evaluated for the oxidation of NH₃ from an airstream. Six-millimeter Celite pellets (R-635) were used for the biological attachment medium. The efficiency of the biofilter in oxidizing NH₃ was evaluated using NH₃ loading rates as high as 48 mol NH₃/m³ hr and empty-bed residence times (EBRTs) as low as 1 min. Excess biomass was controlled through periodic backwashing of the biofilter with water at a rate sufficient to fluidize the medium. The main goal was to demonstrate that high removal efficiencies could be sustained over long periods of operation. Ammonia oxidation efficiencies in excess of 99% were consistently achieved when the pH of the liquid nutrient feed was maintained at 8.5. Quick recovery of the biofilter after backwashing was observed after only 20 min. Evaluation of biofilter performance with depth revealed that NH₃ did not persist in the gas phase beyond 0.3 m into the depth of the medium (26% of total medium depth).     

Long-Term Operation of a Biofilter for Simultaneous Removal of H2S and NH3

Abstract

Simultaneous removal of NH₃ and H₂S was investigated using two types of biofilters—one packed with wood chips and the other with granular activated carbon (GAC). Experimental tests and measurements included analyses of removal efficiency (RE), metabolic products, and results of long-term operation (around 240 days). The REs for NH₃ and H₂S were 92 and 99.9%, respectively, before deactivation. After deactivation, the RE for NH₃ and H₂S were decreased to 30–50% and 75%, respectively. The activity of nitrifying bacteria was inhibited by high concentrations of H₂S (over 200 ppm) but recovered gradually after H₂S addition was ceased. However, the Thiobacillus thioparus as sulfur oxidizing bacteria did not show inhibition at the NH₃ concentration under 150-ppm conditions. The deactivation of the biofilter was caused by metabolic products [elemental sulfur and (NH₄)₂SO₄] ac-cumulating on the packing materials during the extended operation. The removal capacities for NH₃ and H₂S were 6.0–8.0 and 45–75 mg N, S/L/hr, respectively.     

Biological Removal of Gaseous Ammonia in Biofilters: Space Travel and Earth-Based Applications

ABSTRACT

Gaseous NH₃ removal was studied in laboratory-scale biofilters (14-L reactor volume) containing perlite inoculated with a nitrifying enrichment culture. These biofilters received 6 L/min of airflow with inlet NH₃ concentrations of 20 or 50 ppm, and removed more than 99.99% of the NH₃ for the period of operation (101, 102 days). Comparison between an active reactor and an autoclaved control indicated that NH₃ removal resulted from nitrification directly, as well as from enhanced absorption resulting from acidity produced by nitrification. Spatial distribution studies (20 ppm only) after 8 days of operation showed that nearly 95% of the NH₃ could be accounted for in the lower 25% of the biofilter matrix, proximate to the port of entry. Periodic analysis of the biofilter material (20 and 50 ppm) showed accumulation of the nitrification product NO₃ ^- early in the operation, but later both NO₂ ^- and NO₃ ^- accumulated. Additionally, the N-mass balance accountability dropped from near 100% early in the experiments to ~95 and 75% for the 20- and 50-ppm biofilters, respectively. A partial contributing factor to this drop in mass balance accountability was the production of NO and N₂O, which were detected in the biofilter exhaust.     

复合生物滤池处理H2S和NH3的挂膜与工艺条件

采用复合生物滤池(生物滴滤池 生物过滤池)处理H2S和NH3组成的混合恶臭气体,填料分别为经表面改性的天然斜发沸石和木屑.实验研究了该工艺的驯化挂膜情况和主要工艺条件,结果表明,天然斜发沸石和木屑改性后,驯化挂膜周期为10～14 d,比文献中颗粒活性炭挂膜缩短14～18 d.复合生物滤池的最佳工艺条件为:高度120 cm,循环液流量4.56 L/h.同时,生物滴滤池处理水溶性好的NH3气体效果较生物过滤池好,而生物过滤池处理水溶性差的H2S气体较生物滴滤池好.因此,复合生物滤池可用于处理不同水溶性的混合恶臭气体.     

新型微生物菌剂对垃圾渗滤液的除臭效果

利用从食材中筛选纯化的特定微生物制成新型复合菌剂,以不同浓度梯度处理垃圾渗滤液,测定其在自然条件下的嗅阈值,监测NH3和H2S即时挥发浓度的变化,评价菌剂的综合除臭效果,设计三因素三水平实验并采用响应面优化法对反应适宜的实验参数进行了优化。研究结果表明,新型复合菌剂的投加会使垃圾渗滤液嗅阈值明显下降;响应面优化模型分析表明,反应时间2.5 d时和0.5%的菌剂投加对抑制NH3的挥发效果最好,而反应时间2.5 d和0.2%的投入量对抑制H2S的挥发效果最好,氧气的供应情况对两者的挥发抑制效果影响不显著。     

Effects of biofilter media depth and moisture content on removal of gases from a swine barn

Media depth (MD) and moisture content (MC) are two important factors that greatly influence biofilter performance. The purpose of this study was to investigate the combined effect of MC and MD on removing ammonia (NH₃), hydrogen sulfide (H₂S), and nitrous oxide (N₂O) from swine barns. Biofiltration performance of different MDs and MCs in combination based on a mixed medium of wood chips and compost was monitored. A 3 × 3 factorial design was adopted, which included three levels of the two factors (MC: 45%, 55%, and 67% [wet basis]; MD: 0.17, 0.33, and 0.50 m). Results indicated that high MC and MD could improve NH₃ removal efficiency, but increase outlet N₂O concentration. When MC was 67%, the average NH₃ removal efficiency of three MDs (0.17, 0.33, and, 0.50 m) ranged from 77.4% to 78.7%; the range of average H₂S removal efficiency dropped from 68.1–90.0% (1–34 days of the test period) to 36.8–63.7% (35–58 days of the test period); and the average outlet N₂O concentration increased by 25.5–60.1%. When MC was 55%, the average removal efficiency of NH₃, H₂S, and N₂O for treatment with 0.33 m MD was 72.8 ± 5.9%, 70.9 ± 13.3%, and –18.9 ± 8.1%, respectively; and the average removal efficiency of NH₃, H₂S, and N₂O for treatment with 0.50 m MD was 77.7 ± 4.2%, 65.8 ± 13.7%, and –24.5 ±12.1%, respectively. When MC was 45%, the highest average NH₃ reduction efficiency among three MDs was 60.7% for 0.5 m MD, and the average N₂O removal efficiency for three MDs ranged from –18.8% to –12.7%. In addition, the pressure drop of 0.33 m MD was significantly lower than that of 0.50 m MD (p < 0.05). To obtain high mitigation of NH₃ and H₂S and avoid elevated emission of N₂O and large pressure drop, 0.33 m MD at 55% MC is recommended.

Implications: The performances of biofilters with three different media depths (0.17, 0.33, and 0.50 m) and three different media moisture contents (45%, 55%, and 67% [wet basis]) were compared to remove gases from a swine barn. Using wood chips and compost mixture as the biofilters media, the combination of 0.33 m media depth and 55% media moisture content is recommended to obtain good reduction of NH₃ and H₂S, and to simultaneously prevent elevated emission of N₂O and large pressure drop across the media.