颗粒活性炭去除水中甲基叔丁基醚的可行性研究

随着甲基叔丁基醚（MTBE）作为汽油添加剂被持续大量使用，其已成为一种地下水中常见的有机污染物。本文通过纯净水、自来水和地下水中MTBE的平衡吸附容量和微型快速穿透实验（MCRB），比较了5种不同种类活性炭对MTBE的吸附性能。结果显示，苯酚值可准确预测活性炭样品对MTBE的平衡吸附容量大小次序，而丹宁酸值则可大致估计活性炭在实际处理应用时的吸附速度和吸附容量利用率。水样中共存的有机成分降低了活性炭对纯净水中MTBE的吸附容量，在背景TOC较低的去离子水中，活性炭对于MTBE的吸附性能反而比在地下水中降低得更多。穿透实验数据显示双柱串联的处理方式是高效应用活性炭吸附水中MTBE的优选工艺。使用环境友好的竹质活性炭去除地下水中MTBE具有良好的可行性和较高的性价比。     

Adsorptive conversion of nitrogen dioxide from etching vent gases over activated carbon

Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO₂ fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO₂ in the gases. The gases contained 5–55 ppm NO₂ and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO₂ of 54 ppm could be removed, and 47% of the removed NO₂ was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO₂ adsorption. Within EBRTs of 0.076–0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design.

Implications: Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO₂ fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO₂ in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution.     

微波辐射回用活性炭对水中亚甲基蓝和Cd2＋去除效果的研究

考察了微波-活性炭联合处理技术对模拟染料废水中亚甲基蓝和Cd2＋的去除效果。对于100 mL浓度为1 000 mg/L的亚甲基蓝溶液、活性炭用量为10 g时,新活性炭对亚甲基蓝的去除率为99.99%;采用700 W微波对吸附亚甲基蓝的活性炭辐射10 min进行再生并回用,经微波辐射再生10次后活性炭对亚甲基蓝的去除率为99.68%,未经微波作用反复使用10次的活性炭对亚甲基蓝的去除率为85.41%。结果表明：微波处理有效地减缓了活性炭吸附能力的下降速率,实现了活性炭再生和反复使用。在吸附过程中,Cd2＋使活性炭对亚甲基蓝的吸附能力略有下降,而共存的亚甲基蓝则促进了活性炭对Cd2＋的吸附,对新炭和再生后活性炭物理化学特性的表征证明了活性炭对亚甲基蓝的吸附为物理吸附,对Cd2＋的吸附为化学吸附。     

微波辐射回用活性炭对水中亚甲基蓝和Cd~(2+)去除效果的研究

考察了微波-活性炭联合处理技术对模拟染料废水中亚甲基蓝和Cd2+的去除效果。对于100 mL浓度为1 000 mg/L的亚甲基蓝溶液、活性炭用量为10 g时,新活性炭对亚甲基蓝的去除率为99.99%;采用700 W微波对吸附亚甲基蓝的活性炭辐射10 min进行再生并回用,经微波辐射再生10次后活性炭对亚甲基蓝的去除率为99.68%,未经微波作用反复使用10次的活性炭对亚甲基蓝的去除率为85.41%。结果表明:微波处理有效地减缓了活性炭吸附能力的下降速率,实现了活性炭再生和反复使用。在吸附过程中,Cd2+使活性炭对亚甲基蓝的吸附能力略有下降,而共存的亚甲基蓝则促进了活性炭对Cd2+的吸附,对新炭和再生后活性炭物理化学特性的表征证明了活性炭对亚甲基蓝的吸附为物理吸附,对Cd2+的吸附为化学吸附。     

Removal of carbonyl sulfide using activated carbon adsorption

Wastewater treatment plant odors are caused by compounds such as hydrogen sulfide (H2S), methyl mercaptans, and carbonyl sulfide (COS). One of the most efficient odor control processes is activated carbon adsorption; however, very few studies have been conducted on COS adsorption. COS is not only an odor causing compound but is also listed in the Clean Air Act as a hazardous air pollutant. Objectives of this study were to determine the following: (1) the adsorption capacity of 3 different carbons for COS removal; (2) the impact of relative humidity (RH) on COS adsorption; (3) the extent of competitive adsorption of COS in the presence of H2S; and (4) whether ammonia injection would increase COS adsorption capacity. Vapor phase react (VPR; reactivated), BPL (bituminous coal-based), and Centaur (physically modified to enhance H2S adsorption) carbons manufactured by Calgon Carbon Corp. were tested in three laboratory-scale columns, 6 in. in depth and 1 in. in diameter. Inlet COS concentrations varied from 35 to 49 ppmv (86-120 mg/m3). RHs of 17%, 30%, 50%, and 90% were tested. For competitive adsorption studies, H2S was tested at 60 ppmv, with COS at 30 ppmv. COS, RH, H2S, and ammonia concentrations were measured using an International Sensor Technology Model IQ-350 solid state sensor, Cole-Parmer humidity stick, Interscan Corp. 1000 series portable analyzer, and Drager Accuro ammonia sensor, respectively. It was found that the adsorption capacity of Centaur carbon for COS was higher than the other two carbons, regardless of RH. As humidity increased, the percentage of decrease in adsorption capacity of Centaur carbon, however, was greater than the other two carbons. The carbon adsorption capacity for COS decreased in proportion to the percentage of H2S in the gas stream. More adsorption sites appear to be available to H2S, a smaller molecule. Ammonia, which has been found to increase H2S adsorption capacity, did not increase the capacity for COS.     

Adsorption of phenolics on activated carbon--impact of pore size and molecular oxygen

The impact of pore size of activated carbon fibers (ACFs) on adsorption capacity and on the potential for oligomerization of phenolic compounds on the surface of ACFs in the presence of molecular oxygen has been investigated in this study. Compared with granular activated carbon (GAC), ACFs have unique pore size distributions, suitable to be used to elucidate the effect of pore structure on adsorption. Adsorption isotherm data were collected for o-cresol and 2-ethylphenol on four ACFs (ACC-10, ACC-15, ACC-20, and ACC-25) with different micropore volumes and BET surface area and on one type of GAC bituminous base. These isotherms were collected under anoxic (absence of molecular oxygen) and oxic (presence of molecular oxygen) conditions. No significant impact of the presence of molecular oxygen on adsorption capacity was noted for ACC-10. ACC-10 has an average pore width of 19.2 A and total pore volume of 0.43 cm3g(-1). On the other hand, for the remaining ACFs, which have larger average pore width and larger pore volume, significant increase in the adsorptive capacity had been observed when molecular oxygen was present. The GAC gave the greatest difference between anoxic and oxic conditions when compared to all the ACFs studied. Binary adsorption of o-cresol and 2-ethylphenol on ACFs with the least pore size (ACC-10) also showed no significant differences between oxic and anoxic environment. The binary system under both anoxic and oxic conditions was well predicted by the ideal adsorbed solution theory (IAST).     

可吸附有机卤化物的深度处理实验研究

可吸附有机卤化物（AOX）是人为污染的重要标志之一,北京高碑店污水处理厂二级出水中约90％的AOX为可吸附有机氧化物（AOCl),研究了自氧氧化,粒状活性炭吸附,粉末活性炭吸附3种深度处理工艺对二级出水中AOX的去除作用,臭氧的氧化反应最多可去除约38％的AOX,粒状活性炭床可运行3200床体积,吸附容量为0.14mgAOX/g GH-16型活性炭,投加木质粉末活性炭200mg/L及25mg/L的聚合氯化铝,能去除24．7％的AOX。     

Microwave Process for Volatile Organic Compound Abatement

ABSTRACT

The CHA Corporation has completed the U.S. Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based process for the removal and destruction of volatile organic compounds (VOCs) in effluents from noncombustion sources, such as paint booth ventilation streams. Removal of solvents by adsorption, followed by the regeneration of saturated granular activated carbon (GAC) by microwave energy, was achieved in a single fixed-bed reactor. Microwave regeneration of the fixed-bed-saturated carbon restored the original GAC adsorption capacity. After 20 adsorption/regeneration cycles, the adsorption capacity dropped from 13.5 g methyl ethyl ketone (MEK)/100 g GAC to 12.5 g MEK/100 g GAC. During microwave regeneration of the GAC fixed bed, the concentrated desorbed paint solvent was oxidized by passing the solvent mixture through a fixed bed of an oxidation catalyst mixed with silicon carbide in a microwave reactor. A 98% oxidation efficiency was consistently achieved from the oxidation of VOCs in the microwave catalytic reactor.     

Microwave process for volatile organic compound abatement

The CHA Corporation has completed the U.S. Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based process for the removal and destruction of volatile organic compounds (VOCs) in effluents from noncombustion sources, such as paint booth ventilation streams. Removal of solvents by adsorption, followed by the regeneration of saturated granular activated carbon (GAC) by microwave energy, was achieved in a single fixed-bed reactor. Microwave regeneration of the fixed-bed-saturated carbon restored the original GAC adsorption capacity. After 20 adsorption/regeneration cycles, the adsorption capacity dropped from 13.5 g methyl ethyl ketone (MEK)/100 g GAC to 12.5 g MEK/100 g GAC. During microwave regeneration of the GAC fixed bed, the concentrated desorbed paint solvent was oxidized by passing the solvent mixture through a fixed bed of an oxidation catalyst mixed with silicon carbide in a microwave reactor. A 98% oxidation efficiency was consistently achieved from the oxidation of VOCs in the microwave catalytic reactor.     

Effects of humic substances on the decomposition of 2,4-dichlorophenol by ozone after extraction from water into acetic acid through activated carbon

The objectives of this study are to clarify the behavior of humic substances throughout the processes of 2,4-dichlorophenol (2,4-DCP) adsorption on granular activated carbon (GAC) from water and extraction into acetic acid, and the influence of the extracted humic substances on the decomposition of 2,4-DCP by ozone in the acetic acid. The adsorption capacity of GAC for 2,4-DCP was not influenced by the humic substances preloaded to have equilibrium concentration of 24.9mg Cl(-1) (14.5mg Cg(-1)). The adsorption capacity of GAC for 2,4-DCP decreased to one tenth of new GAC after the first adsorption-extraction step because of only 16% desorption in the first step. However, 2,4-DCP adsorbed on GAC was completely extracted after the second step suggesting that GAC can be used as adsorbent to transfer 2,4-DCP from water to acetic acid. The concentration ratio of 2,4-DCP from water into acetic acid was around 2x10(5), whereas the concentration ratio of humic substances was about 3.5, indicating that 2,4-DCP was selectively adsorbed and extracted by this system. The first order degradation rate constant for 2,4-DCP by ozone in acetic acid increased with the addition of humic substances. The rate constant with 16mg Cl(-1) of humic substances was 2.6 times as high as that without humic substances. Humic substances behaved as a promoter for the degradation of 2,4-DCP by ozone.     

高效生物活性炭吸附工艺去除水体中甲基叔丁基醚的初步研究

通过对来自美国加州拉玛达(La Mirada)市污染点的原始菌源炭进行甲基叔丁基醚(MTBE)降解菌生物强化,试图建立具有更有效MTBE降解效果的生物活性炭(BAC)功能,尝试利用新形成的菌源炭覆盖新鲜椰壳活性炭(GAC)而达到新BAC功能的快速有效启动,并考察不同空床停留时间(EBCT)、GAC吸附饱和状态对BAC功能启动的影响。同时,对具有成熟BAC功能的炭柱中的混合菌落进行基于16SrDNA的聚合酶链反应(PCR)—变性梯度凝胶电泳(DGGE)分析,以确定混合菌落中的主要功能菌种属。结果表明,针对模拟的低MTBE浓度进水,新鲜GAC和菌源炭A添加体积分数分别为40%和60%的NAS柱出水MTBE质量浓度最终稳定低于0.005mg/L,平均去除率接近99%,出水MTBE完全达到美国环境保护署(EPA)的饮用水建议阈值(<20μg/L),建立了成熟的BAC功能;成熟的菌源炭可在30d左右通过覆盖法迅速实现新BAC功能的启动;EBCT的延长有利于新BAC功能的启动和维持,接种初期应尽量采用较长EBCT以保证取得足够和稳定的生物量;MTBE吸附饱和前后的GAC在启动新BAC功能时存在差异,鉴于吸附饱和GAC在接种初期会因MTBE解吸而造成出水MTBE浓度较高,建议采用新鲜活性炭覆盖需接种炭柱;BAC功能成熟炭柱中包括的5种主要菌种里有4种为未培养微生物,1种为未分类菌种,其理化性质和具体属性尚不明确。     

Effect of Advanced Oxidants Generated Via Ultraviolet Light on a Sequentially Loaded and Regenerated Granular Activated Carbon Biofilter

Abstract

The objective of this research was to investigate a sequentially loaded and regenerated granular activated carbon (GAC) biofilter system and to determine whether regenerative ozonation/advanced oxidation could improve the removal and biodegradation of a volatile organic compound from a contaminated airstream. Bench-scale reactors were constructed to operate in a manner analogous to a commercially available system manufactured by Terr-Aqua Environmental Systems (only with longer contact time). The GAC system consisted of two GAC biofilter beds that operated in a cyclical manner. On a given day, the first GAC bed adsorbed methyl isobutyl ketone from a simulated waste airstream, while the second bed underwent regeneration; then on the next day, the second bed was in the adsorption mode while the first was regenerated.

Three bench-scale systems were used to compare the performance under three operating conditions: (1) ozone/ associated oxidant regeneration of a GAC biofilter system that was seeded with microorganisms from a field site, (2) a humid air regeneration of a seeded GAC biofilter, and (3) a humid air regeneration of an unseeded GAC biofilter. For the advanced oxidant regenerated GAC biofilter, a maximum removal efficiency of >95% was achieved with an empty bed contact time of 148 sec and an influent concentration of 125 ppm methyl isobutyl ketone, and 90–95% was achieved at 148-sec empty bed contact time and a 1150-ppm influent.     

新型水处理活性炭选型技术

活性炭依其原料不同、生产工艺不同,而有不同的吸附性能.使用简易的活性炭选型方法,可以减少应用测试时的备选炭型,从而大大降低活性炭水处理技术的运行成本.以碘值、甲基蓝值、苯酚值和丹宁酸值4种吸附容量性能指标为依据的活性炭选型技术,可以有效地预测活性炭对于水中各种大小不同污染物的去除能力.BET测试结果证明了这4项指标数据对于活性炭孔径分布预测的准确性.2,4-二氯苯酚和腐殖酸等目标化合物的吸附容量实验结果也都验证了这4项指标的预测功用,说明这种简便的活性炭选型技术有着广泛的应用价值.     

Hydraulic performance of a proposed in situ photocatalytic reactor for degradation of MTBE in water

Methyl tert-butyl ether (MTBE) groundwater remediation projects often require a combination of technologies resulting in increasing the project costs. A cost-effective in situ photocatalytic reactor design, Honeycomb II, is proposed and tested for its efficiency in MTBE degradation at various flows. This study is an intermediate phase of the research in developing an in situ photocatalytic reactor for groundwater remediation. It examines the effect of the operating variables: air and water flow and double passages through Honeycomb II, on the MTBE removal. MTBE vaporisation is affected by not only temperature, Henry’s law constant and air flow to volume ratio but also reactor geometry. The column reactor achieved more than 84% MTBE removal after 8 h at flows equivalent to horizontal groundwater velocities slower than 21.2 cm d⁻¹. Despite the contrasting properties between a photocatalytic indicator methylene blue and MTBE, the reactor efficiency in degrading both compounds showed similar responses towards flow (equivalent groundwater velocity and hydraulic residence time (HRT)). The critical HRT for both compounds was approximately 1 d, which corresponded to a velocity of 21.2 cm d⁻¹. A double pass through both new and used catalysts achieved more than 95% MTBE removal after two passes in 48 h. It also verified that the removal efficiency can be estimated via the sequential order of the removal efficiency of one pass obtained in the laboratory. This study reinforces the potential of this reactor design for in situ groundwater remediation.     

树脂吸附法处理氯霉素中间体DL-氨基物合成废水

研究了树脂吸附法处理氯霉素生产中产生的DL 1 对硝基苯基 2 氨基 1 ,3 丙二醇 (DL 氨基物 )碱解废水的工艺。结果表明 ,NG 1 0 0超高交联吸附树脂对废水中DL 氨基物具有较好的吸附性能。在试验条件下 ,废水CODCr为 72 0 0mg/L ,DL 氨基物含量为 2 86 5mg/L ,批处理 1 7BV时 ,平均出水CODCr降至 89 3mg/L ,CODCr去除率 >98% ;出水中DL 氨基物未检出 ,去除率近 1 0 0 %。树脂经稀酸脱附处理后 ,再生性能良好 ,高浓脱附液可直接回用于氯霉素生产酸性水解工艺中 ,使回收物得到有效利用     

Fate of biodegradable dissolved organic carbon produced by ozonation on biological activated carbon

The adsorption and desorption characteristics of BDOC produced by ozonation and the replacement of BDOC by non-BDOC on BAC was studied. The fate of BDOC produced by ozonation in the BAC column was also evaluated by comparative experiment between the BAC supplied with the mixture of BDOC and non-BDOC and the BAC supplied only with non-BDOC. Fulvic acids extracted from two river sediments and one forest soil were used. BDOC produced by ozonation showed the same or lower adsorption capacity than non-BDOC after biodegradation. The adsorption rate of BDOC on GAC was lower than that of non-BDOC. BDOC produced by ozonation had low desorbability and majority of BDOC produced were not replaced by non-BDOC. BDOC in the ozonated fulvic acid did not affect the breakthrough of the ozonated fulvic acid on GAC in the early stage of adsorption, suggesting that most of BDOC were biodegraded on the surface of GAC before adsorption. Therefore, the production of BDOC by ozonation before the GAC treatment is very effective for the extension of GAC service life and the reduction of DOC loading to GAC.     

三氯乙酸与其他有机物在活性炭上的竞争吸附

通过等温吸附实验,考察了三氯乙酸(TCAA)与十二烷基苯磺酸钠(DBS)、腐殖酸(HA)在活性炭(GAC)上的竞争吸附现象。结果表明,GAC对TCAA的吸附符合Langmuir模型,对DBS和HA的吸附均符合Freudlich模型;在GAC上,DBS和HA对TCAA构成竞争吸附,大分子HA阻塞GAC的微孔,使得TCAA与DBS难以进入微孔;GAC对3种物质的吸附能力由大到小依次为DBS、TCAA和HA;离子型表面活性剂DBS憎水性一端与TCAA竞争吸附位,亲水性一端与TCAA形成吸附,使GAC总饱和吸附量有所加大。     

活性炭纤维及其在水处理中的应用

介绍了活性炭纤维材料的发展历史、类别、结构性能、制备过程。活性炭纤维比普通活性炭性能优越，吸附量大，机械强度高，吸附、脱附速度快，正逐渐地被用于废水处理和饮用水的净化。其具体方法有常用的吸附法、电解法，以及尚在起步阶段的生物活性炭纤维法。     

Removal of acutely hazardous pharmaceuticals from water using multi-template imprinted polymer adsorbent

Molecularly imprinted polymer adsorbent has been prepared to remove a group of recalcitrant and acutely hazardous (p-type) chemicals from water and wastewaters. The polymer adsorbent exhibited twofold higher adsorption capacity than the commercially used polystyrene divinylbenzene resin (XAD) and powdered activated carbon adsorbents. Higher adsorption capacity of the polymer adsorbent was explained on the basis of high specific surface area formed during molecular imprinting process. Freundlich isotherms drawn showed that the adsorption of p-type chemicals onto polymer adsorbent was kinetically faster than the other reference adsorbents. Matrix effect on adsorption of p-type chemicals was minimal, and also polymer adsorbent was amenable to regeneration by washing with water/methanol (3:1, v/v) solution. The polymer adsorbent was unaltered in its adsorption capacity up to 10 cycles of adsorption and desorption, which will be more desirable in cost reduction of treatment compared with single-time-use activated carbon.