Biological removal of gaseous ammonia in biofilters: space travel and earth-based applications

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 approximately 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.     

SBR单级自养脱氮系统氮素转化途径

利用氮素计量关系和批式实验研究了SBR系统中基于短程硝化的单级自养脱氮特性和脱氮途径。结果表明,SBR系统获得良好脱氮效果,TN最高去除负荷和去除速率分别达0.49 kg N/(m3.d)和0.20 kg N/(kg VSS.d);系统中82%的氨氮转化成气体脱除,10%的氨氮转化成硝酸盐氮。批式实验结果表明,SBR系统中的污泥同时具有厌氧氨氧化、亚硝酸盐氧化和自养反硝化活性,三者的反应速率分别为0.12 kg NH4+-N/(kg VSS.d)、0.04 kg NO2--N/(kg VSS.d)和0.03 kg NO2--N/(kg VSS.d)。综上,SBR系统中氮的脱除是短程硝化、厌氧氨氧化和反硝化共同作用的结果,产生的硝酸盐是厌氧氨氧化和硝化作用所致。     

The Statistical Form for the Ambient Participate Standard Annual Arithmetic Mean vs Annual Geometric Mean

Abstract

The long-term stability of a biofilter loaded with waste gases containing NH₃ concentrations larger than 100 ppmv was studied in a laboratory-scale compost reactor. At an empty bed residence time (τ) of 21 sec, elimination capacities of more than 300 g NH₃/m³/day were obtained at elimination efficiencies up to 87%. Because of absorption and nitrification, almost 80% of the NH₃-N eliminated from the waste gas could be recovered in the compost as NH₄+-N or NO₂ ^?/NO₃ ^?-N. The high elimination capacities could be maintained as long as the NH₄+/NO_x concentration in the carrier material was less than 4 g NH₄+/NO_x ^?-N/kg wet compost. Above this critical value, osmotic effects inhibited the nitrifying activity, and the elimination capacity for NH₃ decreased. To restore the biofilter performance, a carbon source (methanol) was added to reduce NH₄+/NO_x ^? accumulated in the compost. Results indicate that methylotrophic microorganisms did convert NH₄+/NO_x ^? into biomass, as long as the NO₃ ^? content in the compost was larger than 0.1 g NO₃ ^?-N/kg compost. Removal efficiencies of CH₃OH of more than 90% were obtained at volumetric loads up to 11,000 g CH₃OH/m³/day. It is shown that addition of CH₃OH is a suitable technique for regenerating the compost material from osmotic inhibition as a result of high NH₃ loading. The biofilter was operated for 4 months with alternating loading of NH₃ and CH₃OH.     

混合固定化硝化菌和好氧反硝化菌处理焦化废水

对传统的聚乙烯醇(PVA)固定化方法进行了改进,试制了加入麦秸粉末的固定化球和以活性炭纤维膜为载体膜固定化细胞产品。混合固定化硝化细菌和好氧反硝化细菌对经过厌氧折流板反应器酸化后的焦化废水进行脱氮,焦化废水在厌氧折流板反应器中经过18 h的酸化后,pH在8.0左右,开始进入好氧槽进行脱氮。在有效容积为5 L好氧槽中经过12 h的曝气处理,加入麦秸粉末的固定化球对氨氮的去除率高达94.3%;纤维膜固定化细胞产品对氨氮的去除率为85%。整个脱氮过程无NO^-₂-N和NO^-₂-N的积累,实现了好氧条件下的同时硝化和反硝化。     

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.     

Control of Organic Emissions from Surface Coating Operations

ABSTRACT

Step tracer tests were carried out on lab-scale biofilters to determine the residence time distributions (RTDs) of gases passing through two types of biofilters: a standard biofilter with vertical gas flow and a modified biofilter with horizontal gas flow. Results were used to define the flow patterns in the reactors. “Non-ideal flow” indicates that the flow reactors did not behave like either type of ideal reactor: the perfectly stirred reactor [often called a "continuously stirred tank reactor" (CSTR)] or the plug-flow reactor.

The horizontal biofilter with back-mixing was able to accommodate a shorter residence time without the usual requirement of greater biofilter surface area for increased biofiltration efficiency. Experimental results indicated that the first bed of the modified biofilter behaved like two CSTRs in series, while the second bed may be represented by two or three CSTRs in series. Because of the flow baffles used in the horizontal biofilter system, its performance was more similar to completely mixed systems, and hence, it could not be modeled as a plug-flow reactor. For the standard biofilter, the number of CSTRs was found to be between 2 and 9 depending on the airflow rate. In terms of NH₃ removal efficiency and elimination capacity, the standard biofilter was not as good as the modified system; moreover, the second bed of the modified biofilter exhibited greater removal efficiency than the first bed. The elimination rate increased as biofilter load increased. An opposite trend was exhibited with respect to removal efficiency.     

复合沸石滤床修复北方景观水体的实验研究

以天然矿物质沸石、细砂及煤渣取代传统滤料构建复合基质生态床,表面种植景观植物,采用下向流-上向流运行方式修复北方景观水体。分别进行静态实验及不同循环速率下的动态实验,考察对水体污染物去除过程。结果表明,2种运行方式下对水体NH⁺₄-N去除率都在85%以上,其中以1 h为循环周期的运行方式去除率达97%,较静态提高12.8%;TN去除率最高为84%;TP去除不稳定,过程缓慢。煤渣层对NH⁺₄-N的去除效果差,硝化作用不彻底与反硝化作用的加强使下层出水NH⁺₄-N 、NO^-₂-N及NO^-₃-N浓度均高于上层。提高循环速率有利于对氮的去除。     

高速泳动床对村镇微污染水体的预处理效果

利用高速泳动床反应器作为预处理装置处理村镇微污染水体,出水进入组合人工湿地。结果表明,实验阶段高速泳动床在HRT为1.2 h时,尽管泳动床进水各污染物浓度较低,但反应器对COD、TN和TP仍具有较明显(P<0.05)的去除效果,平均去除率分别为11.3%、14.6%和25.8%。高速泳动床反应器对氨氮去除效果尤为明显,去除率达到46.9%。此外,高速泳动床反应器内硝化作用较强,出水中硝态氮含量平均增加率为45.5%,弥补了后续人工湿地硝化作用不强、除氨氮效果不佳的缺点。     

生物滤塔和NRB在有氧条件下去除废气中的NOx

研究了有氧条件下氮氧化物在生物滤塔内的传质机理,结果表明,当含NOx废气中氧气含量为20%、氧化度为80%时,被生物滤塔内微生物吸附分解的NOx仅占被净化的NOx的12%左右,而88%左右的NOx没有被微生物及时分解,而是转入液相中形成NO3-和NO2-.在此基础上,提出了采用生物滤塔和硝酸盐脱除反应器(nitrate...     

Methane biofiltration in the presence of ethanol vapor under steady and transient state conditions: an experimental study

Methane (CH₄) removal in the presence of ethanol vapors was performed by a stone-based bed and a hybrid packing biofilter in parallel. In the absence of ethanol, a methane removal efficiency of 55 ± 1% was obtained for both biofilters under similar CH₄ inlet load (IL) of 13 ± 0.5 g_CH4 m^?3 h^?1 and an empty bed residence time (EBRT) of 6 min. The results proved the key role of the bottom section in both biofilters for simultaneous removal of CH₄ and ethanol. Ethanol vapor was completely eliminated in the bottom sections for an ethanol IL variation between 1 and 11 g_ethanol m^?3 h^?1. Ethanol absorption and accumulation in the biofilm phase as well as ethanol conversion to CO₂ contributed to ethanol removal efficiency of 100%. In the presence of ethanol vapor, CO₂ productions in the bottom section increased almost fourfold in both biofilters. The ethanol concentration in the leachate of the biofilter exceeding 2200 g_ethanol m^?3 _leachate in both biofilters demonstrated the excess accumulation of ethanol in the biofilm phase. The biofilters responded quickly to an ethanol shock load followed by a starvation with 20% decrease of their performance. The return to normal operations in both biofilters after the transient conditions took less than 5 days. Unlike the hybrid packing biofilter, excess pressure drop (up to 1.9 cmH₂O m^?1) was an important concern for the stone bed biofilter. The biomass accumulation in the bottom section of the stone bed biofilter contributed to 80% of the total pressure drop. However, the 14-day starvation reduced the pressure drop to 0.25 cmH₂O m^?1.     

Gaseous Ammonia Uptake in Compost Biofilters as Related to Compost Water Content

Abstract

Sewage sludge and yard waste compost were used as biofilter materials and tested with respect to their capacity for removing ammonia from air at different water contents. Ammonia removal was measured in biofilters containing compost wetted to different moisture contents ranging from air dry to field capacity (maximum water holding capacity). Filters were operated for 15 days and subsequently analyzed for NH₃/NH₄ ⁺, NO₂ ^-, and NO₃ ^-. The measured nitrogen species concentration profiles inside the filters were used to calculate ammonia removal rates. The results showed that ammonia removal is strongly dependent on the water content in the filter material. At gravimetric water contents below 0.25 g H₂O g solids^-1 for the yard waste compost and 0.5 g H₂O g solids^-1 ammonia removal rates were very low but increased rapidly above these values. The sewage sludge compost filters yielded more than twice the ammonia removal rate observed for yard waste compost likely because of a high initial concentration of nitrifying bacteria originating from the wastewater treatment process and a high air-water interphase surface area that facilitates effective ammonia dissolution and transport to the biofilm.     

ANAMMOX与反硝化协同作用及氮素负荷研究

向成功启动并稳定运行630 d后的UASB生物膜反应器系统连续添加有机物,分析其对厌氧氨氧化反应脱氮效果的影响,并进行氮素浓度负荷试验.在厌氧氨氧化反应器系统中连续投加有机COD(葡萄糖),系统运行稳定,有机COD(葡萄糖)存在对系统去除氮素能力影响不大,有机COD去除率达到92.0%,仅用23 d,在同一反应器系统中成功实现了厌氧氨氧化与反硝化协同作用脱氮.氮素浓度负荷试验阶段,进水氨氮(NH 4-N)、亚硝氮(NO-2-N)以及总氮(TN)浓度负荷分别从0.063 kg/(m3·d)和0.063 kg/(m3·d)和0.126 kg/(m3·d)提升到了0.239 kg/(m3·d)、0.315 kg/(m3·d)和0.554 kg/(m3·d),相应去除率分别为84.0%、93.0%和85.0%,厌氧氨氧化工艺的UASB生物膜反应器对氮素浓度负荷仍有很大提升空间.     

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.     

Long-term operation of biofilters for biological removal of ammonia

Biological removal of ammonia was investigated using two types of packing materials, compost and sludge in laboratory-scale biofilters (8l reactor volume). The aim of this study is to investigate the potential of unit systems packed with these supports in terms of ammonia emissions treatment. Experimental tests and measurements included analysis of removal efficiency, metabolic products, and results of long-term operation. The inlet concentration of ammonia applied was 20-200 mg m-3. The ammonia loading rates of 24.9-566 g NH3 m-3 d-1 to compost biofilter (BF3) and 24.9-472 g NH3 m-3 d-1 to sludge biofilter (BF4) were applied for 210 days, respectively. Removal efficiencies of the compost and sludge biofilters were in the range of 97-99% and 95-99%, respectively when the inlet concentration of ammonia was below 110 mg m-3, and the maximum elimination capacities were 288 and 243 g NH3m-3d-1, respectively. However, removal efficiency and elimination capacity of both biofilters significantly decreased as the inlet concentration increased to above 110 mg m-3. By using kinetic analysis, the maximum removal rate of ammonia, Vm, and the saturation constant, Ks, were determined for both packing materials and the value of Vm for compost was found to be larger. Periodic analysis of the biofilter packing materials showed the accumulation of the nitrification product NO3- in the operation. During the experiment, the pressure drops measured were very low. The use of both packing materials requires neither nutritive aqueous solution nor buffer solution.     

用微电极测定曝气量对SBR系统中硝化作用的影响

为了研究曝气量对硝化作用的影响,实验采用3个相同的SBR装置,分别在曝气量为4、10和16 L/h的条件下处理人工污水,并采用自制的溶解氧、NO3-、NH4+和pH微电极测定了活性污泥絮体内部微元环境中相应基质的浓度。结果表明,曝气量为4 L/h时,活性污泥絮体内存在厌氧微区,NO3--N浓度减小了,发生了反硝化作用;而曝气量为10 L/h和16 L/h时,活性污泥絮体内发生的都是硝化反应,且NH4+-N浓度的减小量、NO3--N浓度的增大量都随着曝气量的增大而增大,pH随着曝气量的增大而减小。     

不同污泥源条件下ANAMMOX启动及其与反硝化协同脱氮对比

采用城市生活污水配水同时启动两组ASBR,R1接种好氧硝化污泥,R2按2∶1混合接种短程硝化和厌氧氨氧化污泥,研究2个ANAMMOX反应器启动的可行性及其差异。实验结果表明,R1和R2均可成功启动ANAMMOX,R1需130 d,R2仅需73 d;稳定期R1和R2反应器NH4+-N、NO2--N和TN去除率分别达95.30%、91.30%、76.28%和96.2%、98.3%、90.1%,且周期内NH4+-N、NO2--N和NO3--N降解规律相似;R1和R2反应器发生的主要反应为厌氧氨氧化,但同时存在反硝化作用;2组反应器稳定运行后污泥颜色、形态及微生物组成相似,经SEM观察多为球状菌。     

Feasibility Testing of Biofiltration Technology for Remediating Air Contaminated by a Boat Manufacturing Facility

ABSTRACT

This research investigated and compared the use of both bench- and pilot-scale biofilters to determine the effectiveness of controlling styrene, methyl ethyl ketone (MEK), and acetone emissions from an industrial gas waste stream. Critical operating parameters, including contaminant loading rate, temperature, and empty bed contact time, were manipulated in both the laboratory and field. At steady-state conditions, the bench and pilot-scale biofilters showed a 99% removal efficiency for styrene when the contaminant loading rate was less than 50 g m^-3hr^-1 and 40 g m^-3hr^-1, respectively. Although few data points were collected in the pilot-scale reactor where the styrene load was greater than 40 g m^-3hr^-1, the total organic contaminant load including both MEK and acetone typically ranged between 50 g m^-3hr^-1 and 80 g m^-3hr^-1. Greater than 99% removal efficiencies were observed for acetone and MEK in the pilot-scale biofilter at all evaluated loading rates. Also studied were biofilter acclimation and re-acclimation periods. In inoculated bench and pilot biofilter systems, microbial acclimation to styrene was achieved in less than five days. In comparison, no MEK degrading microbial inoculum was added, so during the first months of pilot-scale biofilter operation, MEK removal efficiencies lagged behind those noted with styrene.     

复合生物滤池处理城市高污染水体

采用中试规模复合生物滤池处理城市高污染水体,考察了滤池的最佳运行参数以及对氮和有机物的去除效果。结果表明:滤池容积负荷宜控制为0.3～0.5 kg COD/(m3.d),水力负荷4.5～5 m3/(m2.d),适宜的通风比为9%,当C/N为5～8时,滤池COD、NH4+-N和TN平均去除率分别为80%、83%和63%,达到高效同步硝化反硝化状态。     

土壤渗滤介质系统去除雨水径流污染物

利用昆明当地的土壤在室内填装一个土柱渗滤系统,使用配水浓度模拟昆明市区雨水径流污染物浓度,进行去除雨水径流污染物的实验研究,考察系统对COD、TN、NH4＋、NO3^-、NO2^-和TP的去除效果。实验结果表明,该土壤渗滤系统对COD平均去除率为82．04％,对TN的平均去除率为22．64％,对NH;平均去除率为94．26％,但是对NO3^-、NO2^-去除效果较差,对TP平均去除率为96．95％;另外,系统长期运行导致下渗速度降低,出水效果反而变好。     

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).