城市污水处理厂除臭生物滤池运行效果及影响因素研究

对山东某城市污水处理厂散发的恶臭气体进行除臭研究,考察了除臭生物滤池的运行效果、工艺影响因素和除臭生物滤池内微生物相特点。结果表明:(1)在进气量为828 m3/h、气体停留时间为30 s、硫化氢和氨进气质量浓度分别为0.5~28.4、0.9~34.3 mg/m3的条件下,稳定运行时,大部分时间硫化氢和氨去除率分别达98%和80%以上,而且除臭生物滤池对于进气负荷具有较强的抗冲击能力。(2)当填料含湿量为43.6%~63.4%时,硫化氢去除率在90%以上;氨去除受填料含湿量的影响较大,填料含湿量越高越利于氨的去除。(3)在处理低浓度含硫化氢和氨的恶臭气体时,生物除臭工程可以在低填料pH(3.0左右)下长期运行,并保持较高的恶臭气体去除率。(4)运行第60天后,当温度为10℃以上时,硫化氢和氨去除率几乎不受影响;第169天后,当温度降至10℃以下时,硫化氢和氨去除率均有一定程度的下降,最低分别为94.6%和79.8%。(5)除臭生物滤池稳定运行时,优势硫氧化菌主要为嗜酸性硫细菌。     

生物滤池高径比对其去除恶臭物质和微生物气溶胶特性的影响

为研究生物滤池不同高径比对恶臭物质(H2S、NH3)和微生物气溶胶(细菌和真菌)的去除率影响,设计了不同高径比(1∶1、2∶1、4∶1、6∶1和8∶1)的生物滤池,研究其处理效果。结果表明:(1)H2S和NH3的去除率均随生物滤池高径比的增大而升高,高径比为8∶1时不同气体停留时间下的H2S和NH3去除率均最高。(2)细菌和真菌的去除率也均随高径比的增大而升高,也是高径比为8∶1时不同气体停留时间下的细菌和真菌去除率均最高。(3)生物滤池高径比较小时,细菌和真菌的粒径相对较小;而生物滤池高径比较大时,细菌和真菌的粒径相对较大。由此可见,增大生物滤池高径比可以有效提高恶臭物质和微生物气溶胶的去除率,减少小粒径的微生物气溶胶排放,最佳高径比为8∶1。     

酸性洗涤塔-生物滤塔-生物曝气池组合工艺处理恶臭气体NH3和H2S

采用酸性洗涤塔、生物滤塔和生物曝气池的组合工艺处理NH3、H2S恶臭混合气体,研究表明,该组合工艺对NH3和H2S有很好的去除效果,在进气流量为35 L/min,喷淋量45 L/h时,NH3进气浓度50.15~525.4 mg/m3,H2S进气浓度10.23~110.36 mg/m3时,NH3单一进气去除率稳定在99%以上,H2S单一进气去除率90%以上。混合进气后,NH3去除率几乎为100%,H2S的去除率提高至98%以上。在一定的浓度范围内,NH3和H2S之间的相互作用对两者的去除效果没有明显的影响,而且起到了相互促进降解的作用。同时,进气流量和填料层高度都会影响NH3、H2S的去除率。系统对进气容积负荷变化的缓冲能力强,在偶尔超负荷条件下运行并不能使系统崩溃,并且微生物对高负荷逐渐表现出适应性。大部分溶于水的氨由生物曝气池去除,去除率达到96.9%。     

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.     

复合式生物除臭反应器处理城市污水处理厂恶臭气体

采用复合式生物除臭反应器处理北京某城市污水处理厂污泥浓缩池和脱水间散发的恶臭气体，研究了反应器对恶臭气体的净化效果和微生物悬浮生长区与附着生长区内的生物特性及对恶臭污染物的去除能力。该污水处理厂的恶臭气体中主要发臭物质为硫化氢和氨，除臭反应器的运行结果表明，在设备稳定运行期间，进气中硫化氢和氨的浓度分别为0.21～22.61 mg/m³和0.1～0.5 mg/m³，而出气中硫化氢浓度在0～0.06 mg/m³，氨浓度为0～0.02 mg/m³。对反应器内部测试表明，微生物悬浮生长区和附着生长区对硫化氢和氨都有一定的去除，但去除机理不同。硫化氢主要被附着生长区的嗜酸性硫细菌生物氧化,少量硫化氢在悬浮区溶于水被中性硫细菌氧化；氨主要在悬浮区靠生物硝化作用去除，少部分氨在附着区被去除，且多因化学中和作用转移到填料所含的水中。     

2种曝气生物滤池的启动比较分析

分别采用陶粒和沸石作为曝气生物滤池的填料,在相同运行参数下进行曝气生物滤池启动对比研究,分析挂膜过程中COD、NH4+-N和浊度的去除效果。试验结果表明,在平均气温为30℃的条件下,2种曝气生物滤池都能很快完成启动挂膜,陶粒曝气生物滤池所需时间为12d,沸石曝气生物滤池所需时间为15d;陶粒曝气生物滤池具有更好的COD去除效果,沸石曝气生物滤池具有更好的NH4+-N去除效果;2个滤池对浊度都能够达到95%左右的去除率。     

组合填料生物滤池处理锦纶废水二级出水的性能研究

为解决纺织行业水回用问题,采用陶粒和活性炭组合填料生物滤池对锦纶废水二级生物处理出水进行了深度净化,并考察了气水比和水力负荷对曝气生物滤池处理效果的影响.研究结果表明,曝气生物滤池处理效果良好,平均出水COD、NH4 -N和TN分别为32 mg/L、1.5 mg/L和8.1 mg/L.随着气水比的增加,COD和NH4 -N平均去除率相应提高,TN平均去除率先增大后降低,当气水比为2∶1时,COD、NH4 -N和TN平均去除率分别为48.30%、84.24%和42.18%;随着水力负荷的增加,COD、NH4 -N和TN平均去除率均降低,当水力负荷为0.39 m3/m2·h时,COD、NH4 -N和TN平均去除率分别为48.33%、84.81%和42.54%.     

喷淋条件对生物滴滤塔去除含H_2S废气的影响

以竹炭为填料,采用高效生物滴滤塔(BTF)中试装置处理污水提升泵站产生的以H2S为主的废气,考察了喷淋时间和喷淋频率对塔内轴向H2S去除率、滤出液中SO2-4浓度和pH、塔内压降的影响。结果表明:当生物滴滤塔系统的空塔停留时间为6.43 s,喷淋时间和喷淋频率分别为1 min·次~(-1)和1次·(60 min)~(-1),BTF对H2S去除效果最好,去除率达99.0%以上,达到《城镇污水处理厂污染物排放标准》(GB 18918~(-2)002)一级厂界排放标准;BTF滤出液中的pH值稳定在2.0~3.0之间,塔内的微生物为嗜酸性硫氧化菌;BTF对H2S的降解符合Michaelis-Menten动力学模型,在适宜喷淋条件下,BTF内的表观半饱和常数(Ks)和最大表观去除速率(Vm)分别为86.8 mg·m-3和22.3 g·(m3·h)~(-1),系统具有较高的抗负荷冲击能力。     

土壤生物过滤去除畜禽养殖臭气

研究土壤生物过滤去除畜禽养殖臭气,旨在为土壤生物滤体除臭装置主要结构参数和运行参数及其优化配置提供依据。建立能同时进行多个处理的生物过滤除臭实验装置,分析影响土壤生物过滤法除臭效果的环境因子。结果表明,活性滤料组合草腐土75%,珍珠岩20%,黑炭5%,滤层高度1 000 mm,滤料表面负荷18 m3/(m2.h),滤料湿度55%的条件下,主要恶臭气体和温室气体释放物NH3、CH4、H2S和CO2去除率>95%,CO和NO2去除率>85%,与畜禽臭气共同扩散的总挥发性有机物(TVOC)、可吸入颗粒物(PM10)和总悬浮物(TSP)去除率>95%,系统排出气体的臭气浓度7.5～8.0,均符合达标排放要求。系统加湿策略应控制滤料湿度(52±3)%,不会出现气道"短路"现象,除臭效果稳定。     

Biostyr曝气生物滤池处理城市污水的沿程生化特性

青岛市麦岛污水处理厂采用曝气生物滤池(BAF)处理城市污水,以稳定运行的Biostyr为研究载体,考察滤池COD、NH3-N、SS和细菌数量等生化特性的沿程变化.结果表明,在气水比为4∶1～5∶1、进水COD负荷为2.5 ～3.7 kg/(m3·d)、进水NH3-N负荷为0.18～0.57 kg/(m3·d)时,滤池对COD的降解主要在150 cm填料以下处,COD的去除率可达58.9％;NH3-N去除率沿滤柱高度的变化与COD有所不同,在100 cm以下填料处,NH3-N的去除率仅为3.6％,在100 ～350 cm填料之间,NH3-N的去除率增加迅速,可达56.1％;对SS的去除主要发生在100 cm填料以下,去除率达51.7％.     

Two-stage biofilter for effective NH3 removal from waste gases containing high concentrations of H2S

A high H2S concentration inhibits nitrification when H2S and NH3 are simultaneously treated in a single biofilter. To improve NH3 removal from waste gases containing concentrated H2S, a two-stage biofilter was designed to solve the problem. In this study, the first biofilter, inoculated with Thiobacillus thioparus, was intended mainly to remove H2S and to reduce the effect of H2S concentration on nitrification in the second biofilter, and the second biofilter, inoculated with Nitrosomonas europaea, was to remove NH3. Extensive studies, which took into account the characteristics of gas removal, the engineering properties of the two biofilters, and biological parameters, were conducted in a 210-day operation. The results showed that an average 98% removal efficiency for H2S and a 100% removal efficiency for NH3 (empty bed retention time = 23-180 sec) were achieved after 70 days. The maximum degradation rate for NH3 was measured as 2.35 g N day(-1) kg of dry granular activated carbon(-1). Inhibition of nitrification was not found in the biofilter. This two-stage biofilter also exhibited good adaptability to shock loading and shutdown periods. Analysis of metabolic product and observation of the bacterial community revealed no obvious acidification or alkalinity phenomena. In addition, a lower moisture content (approximately 40%) for microbial survival and low pressure drop (average 24.39 mm H2O m(-1)) for system operation demonstrated that the two-stage biofilter was energy saving and economic. Thus, the two-stage biofilter is a feasible system to enhance NH3 removal in the concentrated coexistence of H2S.     

Biotreatment of H2S- and NH3-containing waste gases by co-immobilized cells biofilter

Gas mixture of H2S and NH3 in this study has been the focus in the research area concerning gases generated from the animal husbandry and the anaerobic wastewater lagoons used for their treatment. A specific microflora (mixture of Thiobacillus thioparus CH11 for H2S and Nitrosomonas europaea for NH3) was immobilized with Ca-alginate and packed inside a glass column to decompose H2S and NH3. The biofilter packed with co-immobilized cells was continuously supplied with H2S and NH3 gas mixtures of various ratios, and the removal efficiency, removal kinetics, and pressure drop in the biofilter was monitored. The results showed that the efficiency remained above 95% regardless of the ratios of H2S and NH3 used. The NH3 concentration has little effect on H2S removal efficiency, however, both high NH3 and H2S concentrations significantly suppress the NH3 removal. Through product analysis, we found that controlling the inlet ratio of the H2S/NH3 could prevent the biofilter from acidification, and, therefore, enhance the operational stability. Conclusions from bioaerosol analysis and pressure drop in the biofilter suggest that the immobilized cell technique creates less environmental impact and improves pure culture operational stability. The criteria for the biofilter operation to meet the current H2S and NH3 emission standards were also established. To reach Taiwan's current ambient air standards of H2S and NH3 (0.1 and 1 ppm, respectively), the maximum inlet concentrations should not exceed 58 ppm for H2S and 164 ppm for NH3, and the residence time be kept at 72 s.     

Full-scale biofilter reduction efficiencies assessed using portable 24-hour sampling units

Portable 24-hr sampling units were used to collect air samples from eight biofilters on four animal feeding operations. The biofilters were located on a dairy, a swine nursery, and two swine finishing farms. Biofilter media characteristics (age, porosity, density, particle size, water absorption capacity, pressure drop) and ammonia (NH3), hydrogen sulfide (H2S), sulfur dioxide (SO2), methane (CH4), and nitrous oxide (N2O) reduction efficiencies of the biofilters were assessed. The deep bed biofilters at the dairy farm, which were in use for a few months, had the most porous media and lowest unit pressure drops. The average media porosity and density were 75% and 180 kg/m3, respectively. Reduction efficiencies of H2S and NH3 (biofilter 1: 64% NH3, 76% H2S; biofilter 2: 53% NH3, 85% H2S) were close to those reported for pilot-scale biofilters. No N2O production was measured at the dairy farm. The highest H2S, SO2, NH3, and CH4 reduction efficiencies were measured from a flat-bed biofilter at the swine nursery farm. However, the highest N2O generation (29.2%) was also measured from this biofilter. This flat-bed biofilter media was dense and had the lowest porosity. A garden sprinkler was used to add water to this biofilter, which may have filled media pores and caused N2O production under anaerobic conditions. Concentrations of H2S and NH3 were determined using the portable 24-hr sampling units and compared to ones measured with a semicontinuous gas sampling system at one farm. Flat-bed biofilters at the swine finishing farms also produced low amounts of N2O. The N2O production rate of the newer media (2 years old) with higher porosity was lower than that of older media (3 years old) (P = 0.042).     

Operational characteristics of effective removal of H2S and NH3 waste gases by activated carbon biofilter

Simultaneous removal of hydrogen sulfide (H2S) and ammonia (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.     

Long-term operation of a biofilter for simultaneous removal of H2S and NH3

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] accumulating 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.     

Biotreatment of hydrogen sulfide- and ammonia-containing waste gases by fluidized bed bioreactor

Gas mixtures of H2S and NH3 are the focus of this study of research concerning gases generated from animal husbandry and treatments of anaerobic wastewater lagoons. A heterotrophic microflora (a mixture of Pseudomonas putida for H2S and Arthrobacter oxydans for NH3) was immobilized with Ca-alginate and packed into a fluidized bed reactor to simultaneously decompose H2S and NH3. This bioreactor was continuously supplied with H2S and NH3 separately or together at various ratios. The removal efficiency, removal rate, and metabolic product of the bioreactor were studied. The results showed that the efficiency remained above 95% when the inlet H2S concentration was below 30 ppm at 36 L/hr. Furthermore, the apparent maximum removal and the apparent half-saturation constant were 7.0 x 10(-8) g-S/cell/day and 76.2 ppm, respectively, in this study. The element sulfur as a main product prevented acidification of the biofilter, which maintained the stability of the operation. As for NH3, the greater than 90% removal rate was achieved as long as the inlet concentration was controlled below 100 ppm at a flow rate of 27 L/hr. In the NH3 inlet, the apparent maximum removal and the apparent half-saturation constant were 1.88 x 10(-6) g-N/cell/day and 30.5 ppm, respectively. Kinetic analysis showed that 60 ppm of NH3 significantly suppressed the H2S removal by Pseudomonas putida, but H2S in the range of 5-60 ppm did not affect NH3 removal by Arthrobacter oxydans. Results from bioaerosol analysis in the bioreactor suggest that the co-immobilized cell technique applied for gas removal creates less environmental impact.     

Removal of ammonia from contaminated air by trickle bed air biofilters

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).     

Bench-scale biofilter for removing ammonia from poultry house exhaust

A bench-scale biofilter was evaluated for removing ammonia (NH3) from poultry house exhaust. The biofilter system was equipped with a compost filter to remove NH3 and calcium oxide (CaO) filter to remove carbon dioxide (CO2). Removal of NH3 and CO2 from poultry house exhaust could allow treated air with residual heat to be recirculated back into the poultry house to conserve energy during winter months. Apart from its use as a plant nutrient, NH3 removal from poultry house exhaust could lessen the adverse environmental impacts of NH3 emissions. Ammonia and CO2 were measured daily with gas detector tubes while temperatures in the poultry pen and compost filter were monitored to evaluate the thermal impact of the biofilter on treated air. During the first 37 days of the 54-day study, exhaust air from 33 birds housed in a pen was treated in the biofilter; for the final 17 days, NH3-laden exhaust, obtained by applying urea to the empty pen was treated in the biofilter. The biofilter system provided near-complete attenuation of a maximum short-term NH3 concentration of 73 ppm. During the last 17 days, with a mean influent NH3 concentration of 26 ppm, the biofilter provided 97% attenuation. The CaO filter was effective in attenuating CO2. Compared with a biofilter sized only for NH3 removal, an oversized biofilter would be required to provide supplemental heat to the treated air through exothermic biochemical reactions in the compost. The biofilter could conserve energy in poultry production and capture NH3 for use as plant nutrient. Based on this study, a house for 27,000 broilers would require a compost filter with a volume of approximately 34 m3.     

Abatement of ammonia and hydrogen sulfide emissions from a swine lagoon using a polymer biocover

The purpose of this research was to determine the efficiency of a polymer biocover for the abatement of H2S and NH3 emissions from an east-central Missouri swine lagoon with a total surface area of 7800 m2. The flux rate of NH3, H2S, and CH4 was monitored continuously from two adjacent, circular (d = 66 m) control and treatment plots using a nonintrusive, micrometeorological method during three independent sampling periods that ranged between 52 and 149 hr. Abatement rates were observed to undergo a temporal acclimation event in which NH3 abatement efficiency improved from 17 to 54% (p = < 0.0001 to 0.0005) and H2S abatement efficiency improved from 23 to 58% (p < 0.0001) over a 3-month period. The increase in abatement efficiency for NH3 and H2S over the sampling period was correlated with the development of a stable anaerobic floc layer on the bottom surface of the biocover that reduced mass transfer of NH3 and H2S across the surface. Analysis of methanogenesis activity showed that the biocover enhanced the rate of anaerobic digestion by 25% when compared with the control. The biocover-enhanced anaerobic digestion process was shown to represent an effective mechanism to counteract the accumulation of methanogenic substrates in the biocovered lagoon.     

Sulfur toxicity and media capacity for H2S removal in biofilters packed with a natural or a commercial granular medium

Two types of media, a natural medium (wood chips) and a commercially engineered medium, were evaluated for sulfur inhibition and capacity for removal of hydrogen sulfide (H2S). Sulfate was added artificially (40, 65, and 100 mg of S/g of medium) to test its effect on removal efficiency and the media. A humidified gas stream of 50 ppm by volume H2S was passed through the media-packed columns, and effluent readings for H2S at the outlet were measured continuously. The overall H2S baseline removal efficiencies of the column packed with natural medium remained >95% over a 2-day period even with the accumulated sulfur species. Added sulfate at a concentration high enough to saturate the biofilter moisture phase did not appear to affect the H2S removal process efficiency. The results of additional experiments with a commercial granular medium also demonstrated that the accumulation of amounts of sulfate sufficient enough to saturate the moisture phase of the medium did not have a significant effect on H2S removal. When the pH of the biofilter medium was lowered to 4, H2S removal efficiency did drop to 36%. This work suggests that sulfate mass transfer through the moisture phase to the biofilm phase does not appear to inhibit H2S removal rates in biofilters. Thus, performance degradation for odor-removing biofilters or H2S breakthrough in field applications is probably caused by other consequences of high H2S loading, such as sulfur precipitation.