活性炭纤维基催化剂在烟气脱硝中的应用

以活性炭纤维（ACF）为载体的催化剂具有良好的脱硝性能，材料、负载方式、负载量、活性组分等的不同都会对NOx的脱除率有很大的影响。在目前研究中，活性炭纤维基催化剂主要应用于催化分解法和选择性催化还原法（SCR）。本文介绍了活性炭纤维的基本特性，比较了不同催化剂的脱硝性能，并在此基础上提出了今后的研究方向。     

蜂窝状活性炭研究

蜂窝状活性炭是一种新型的活性炭。简要介绍了蜂窝状活性炭的结构特性和吸附性能，重点总结了蜂窝状活性炭基催化剂的制备方法及其在催化方面的应用。     

ACF表面化学官能团对影响脱硫性能的研究进展

活性炭纤维(ACF)作为第三代活性炭,是一种新型的高效吸附剂和催化剂。它具有独特的物理性能和化学性能,对烟气中的SO2具有很强的吸附和催化氧化作用,因此作为烟气脱硫方面极具前景的催化剂而受到人们的普遍关注。以聚丙烯腈基活性炭纤维(PAN-ACF)为代表,主要深入探讨了ACF表面化学官能团对脱硫性能的影响。     

挥发性有机废气净化技术研究进展

本文对生物净化技术、等离子体净化技术、吸附和催化氧化技术在控制废气中挥发性有机物的研究进展及应用进行了综述。气体生物净化技术在VOCs混合物和改进设备工艺方面开展的研究工作较多,等离子体净化技术与催化技术的组合越来越受到关注。吸附和催化氧化方面则着重在吸附剂（活性炭和沸石）吸附性能的进一步研究和新型催化剂的研制。     

凹凸棒石黏土在烟气脱硝中的研究进展

当前我国脱硝行业控制氮氧化物排放很大程度上决定于催化剂的性能、成本等。广泛使用的二氧化钛基脱硝催化剂尽管性能好,但成本较高。相反,具有"千种用土"、"万土之王"的凹凸棒石黏土兼具性能良好和成本低廉的特点,因此可考虑用于脱硝。简述了凹凸棒石黏土的组成、资源分布、开发现状及其主要性能(吸附性和催化性),分析总结了凹凸棒石黏土基脱硝用催化剂的研究进展。研究将凹凸棒石黏土用作催化剂载体或者催化载体粘结剂制备出的催化剂,多以负载金属或者过渡金属作为催化活性组分,脱硝率一般都能达80%以上,部分催化剂在一定SO2浓度下依然有较好的催化转化效率。研究发现,凹凸棒石黏土基脱硝催化剂具有较好的催化反应性能,不仅有望一体式解决脱硝、脱汞、抗硫等问题,而且还将大大降低脱硝成本。     

O3/H2O2协同催化处理煤化工高盐有机废水的研究

煤化工高盐废水中有机物的处理是废水零排放项目能否成功运行的关键性因素,制备了一种铁基活性炭催化剂,并采用O₃/H₂O₂协同催化技术处理煤化工高盐废水,可以显著提高废水中有机物的处理效果。采用扫描电子显微镜(SEM)、穆斯堡尔谱、X射线荧光光谱仪(XRF)、X射线衍射(XRD)等手段对催化剂进行表征,考察处理工艺、氧化剂加入量和反应时间对废水中有机物去除效果的影响,评价催化剂的稳定性和催化性能。结果表明,本催化剂用于O₃/H₂O₂协同催化处理煤化工高盐有机废水时,TOC去除率提高至54.41%;连续稳定运行1800 h后催化剂的催化活性基本保持不变。提供的催化剂及O₃/H₂O₂协同催化工艺可以高效处理煤化工高盐废水中的有机物,解决废水零排放项目中的难点,具有广阔的市场应用前景。     

二次催化-固定床生物氧化降解焦化废水的试验研究

制备了一种铁碳基／过渡金属复合催化剂，其物质摩尔配比为Fe：C：TiO2：MnO2：ZnO=2：1：1：1：0．3，使用该催化剂拟定了二次催化—固定床生物氧化降解流程。在pH＝6、温度=90℃的条件下，用该流程处理煤化工工业所产生的洗煤气净化脱酚、蒸氨剩余废水，在无需对原废水进行稀释的前提下可很好地对此废水进行处理，使处理后的出水指标达到《污水综合排放标准》（GB89r78—1966）中规定的二级排放标准。     

低温等离子体耦合催化剂降解VOCs的研究进展

文章对近十年来等离子体催化降解VOCs技术进行了调查研究并进行综述,简要介绍低温等离子体技术,通过分析低温等离子体催化不同的耦合方式,对贵金属、过渡金属氧化物、双金属、光催化剂等4种类型催化剂的研究进展进行概述;从湿度、背景气体、氧浓度和催化剂制备参数等方面概述低温等离子体催化影响因素方面的研究进展;不同的催化剂及其他影响因素对VOCs的降解效果及副产物的影响。最后对低温等离子协同催化技术降解VOCs的机理进行阐述。     

载铜活性炭催化氧化干法腈纶废水的研究

通过浸渍法制备了载铜活性炭(Cu/AC)催化剂,用于催化过氧化物氧化干法腈纶废水,结果表明:Cu/AC催化活性高于均相催化剂Cu(NO3)2,Cu溶出量则小于均相催化剂.非均相催化氧化对干法腈纶废水有很好的处理效果.催化剂的活性和稳定性与制备条件关系很大,通过单因子影响实验,确定催化剂的最佳制备条件为焙烧温度700℃,焙烧时间4小时,浸渍溶液初始浓度10.6gCu/L,浸渍时间20小时.     

负载金属活性碳纤维对NO催化分解性能的研究

碳纤维用于环境保护,污染治理是个重要课题,采用浸渍法研制系列钯负载活性碳纤维,研究了它们对NO的歧化分解性能,并与其它载体催化剂进行比较,实验结果表明负载钯活性碳纤维在300℃以上能催化NO的歧化分解。负载钯活性炭和负载钯炭黑分解NO的能力明显比前者弱,石墨和分子筛载体负载钯催化剂在400℃仍没有催化分解NO的作用。催化反应温度升高,NO流量降低,钯负载量增加有利于NO分解率提高,采用钯－铜混合物负载活性碳纤维可以减少钯的使用量。     

炭基催化剂用于处理H2S的研究进展＊

介绍了国内外在常温下处理硫化氢等恶臭气体的炭基催化剂的研究进展情况,分析了炭基催化剂中活性炭、活性炭纤维、超级活性炭的特性及国内外应用现状,从工艺技术、成本、环保等几方面总结了此类常温脱硫催化剂的应用情况和优缺点,并对炭基脱硫催化剂未来的应用空间和发展方向进行了展望。     

废水生物脱氮低温反硝化研究进展

反硝化过程是废水生物脱氮的关键,低温下废水生物处理的反硝化效率显著降低.本文从低温对微生物反硝化处理效果的影响、低温对反硝化微生物的影响机制以及低温下反硝化效果的强化策略等方面的研究展开综述,并提出了可能的研究方向,以期为微生物低温反硝化进一步的机理研究与技术强化提供参考.     

城镇污水处理厂NPR工艺低温运行的效能分析

介绍了天津市某城镇污水处理厂NPR工艺的特点及运行状况。通过对污水厂的运行监测数据分析,研究了该工艺在低温条件下处理城镇生活污水时的脱氮除磷效果。结果表明:NPR工艺具有一定的优异性,它能在降低能耗的前提下使系统COD和SS的去除率进一步降低,出水能达到中水回用标准,有利于污水的再生利用;低温影响NPR系统的硝化及反硝化率,低温下有机物的去除更易受到有机负荷的影响;温度对生物去除SS,COD和TP的效果影响不大,对NH3-N及TN的去除效果影响比较明显。低温下污水处理厂COD、SS、NH3-N、TN、TP的平均去除率分别为72.1%、94.9%、67.5%、55.1%、66.5%。     

In situ ground water denitrification in stratified, permeable soils underlying riparian wetlands

The ground water denitrification capacity of riparian zones in deep soils, where substantial ground water can flow through low-gradient stratified sediments, may affect watershed nitrogen export. We hypothesized that the vertical pattern of ground water denitrification in riparian hydric soils varies with geomorphic setting and follows expected subsurface carbon distribution (i.e., abrupt decline with depth in glacial outwash vs. negligible decline with depth in alluvium). We measured in situ ground water denitrification rates at three depths (65, 150, and 300 cm) within hydric soils at four riparian sites (two per setting) using a 15N-enriched nitrate "push-pull" method. No significant difference was found in the pattern and magnitude of denitrification when grouping sites by setting. At three sites there was no significant difference in denitrification among depths. Correlations of site characteristics with denitrification varied with depth. At 65 cm, ground water denitrification correlated with variables associated with the surface ecosystem (temperature, dissolved organic carbon). At deeper depths, rates were significantly higher closer to the stream where the subsoil often contains organically enriched deposits that indicate fluvial geomorphic processes. Mean rates ranged from 30 to 120 microg N kg(-1) d(-1) within 10 m versus <1 to 40 microg N kg(-1) d(-1) at >30 m from the stream. High denitrification rates observed in hydric soils, down to 3 m within 10 m of the stream in both alluvial and glacial outwash settings, argue for the importance of both settings in evaluating the significance of riparian wetlands in catchment-scale N dynamics.     

The effect of landfill leachate composition on organics and nitrogen removal in an activated sludge system with bentonite additive

A pre-denitrification activated sludge system (AS) without internal recycle was used in lab-scale studies of landfill leachate treatment. A bentonite supplement at a ratio of 1:4 (mineral : biomass) was used to ensure high sludge settling levels and to serve as a micro-organisms carrier. The system was operated within different parameters such as hydraulic retention time (HRT), ammonia loading rate (ALR) or external recycle ratio, which was adapted to treat varying leachate concentrations of COD and ammonia, ranging from 1020 to 2680 mgO(2)l(-1) and 400-890 mgNH(4)-Nl(-1) respectively. The nitrification was complete and ammonia oxidation reached 99%; this was obtained while the ALR did not exceed 0.09 g NH(4)(+)-Ng(-1)MLVSS d(-1) and HRT was not lower than 1 day (in the aeration reactor). The performance of denitrification was successfully improved by controlling the external recycle rate, when the BOD(5)/N ratio in the raw leachate was 4.1. Consequently, N-removal of up to 80% was achieved. A 10-fold decrease in the denitrification rate was obtained at a BOD(5)/N ratio of 0.5. The efficiency of COD removal varied significantly from 36% to 84%. The positive effect of bentonite addition was determined and is discussed based on preliminary studies. The experiments were carried out in fill-and-draw activated sludge with bentonite; the biomass ratio was 1:2. The activated sludge with bentonite was fed with a synthetic high ammonia and organic-free medium.     

Evaluation of nitrate nitrogen fluxes from a tile-drained watershed in central Iowa

Nitrate N fluxes from tile-drained watersheds have been implicated in water quality studies of the Mississippi River basin, but actual NO3-N loads from small watersheds during long periods are poorly documented. We evaluated discharge and NO3-N fluxes passing the outlet of an Iowa watershed (5134 ha) and two of its tile-drained subbasins (493 and 863 ha) from mid-1992 through 2000. The cumulative NO3-N load from the catchment was 168 kg ha(-1), and 176 and 229 kg ha(-1) from the subbasins. The outlet had greater total discharge (1831 mm) and smaller flow-weighted mean NO3-N concentration (9.2 mg L(-1)) than the subbasins, while the larger subbasin had greater discharge (1712 vs. 1559 mm) and mean NO3-N concentration (13.4 vs. 11.3 mg L(-1)) than the smaller subbasin. Concentrations exceeding 10 mg L(-1) were common, but least frequent at the outlet. Nitrate N was generally not diluted by large flows, except during 1993 flooding. The outlet showed smaller NO3-N concentrations at low flows. Relationships between discharge and NO3-N flux showed log-log slopes near 1.0 for the subbasins, and 1.2 for the outlet, considering autocorrelation and measurement-error effects. We estimated denitrification of subbasin NO3-N fluxes in a hypothetical wetland using published data. Assuming that temperature and NO3-N supply could limit denitrification, then about 20% of the NO3-N would have been denitrified by a wetland constructed to meet USDA-approved criteria. The low efficiency results from the seasonal timing and NO3-N content of large flows. Therefore, agricultural and wetland best management practices (BMPs) are needed to achieve water quality goals in tile-drained watersheds.     

CAST工艺脱氮的研究

在CAST工艺中，通过控制活性污泥工艺的反应环境可以使氮的去除过程优化。将传统的处理方法和周期循环运行过程的处理效果做长时间的比较，通过检测比较硝化速率，同时硝化反硝化以及除磷效果，可知，当运行负荷相同时，周期循环运行过程是一种很有优势的污水处理方法。     

Denitrification as a nitrogen removal mechanism in a Vermont peatland

Atmospheric deposition of nitrogenous compounds to ombrotrophic peatlands (i.e., those that have peat layers higher than their surroundings and receive nutrients and minerals exclusively by precipitation) has the potential to significantly alter ecosystem functioning. This study utilized the acetylene inhibition technique to estimate the relative importance of denitrification in nitrogen removal from a primarily ombrotrophic peatland, in an attempt to estimate the threat of increased nitrogen loadings to these areas. Estimates of mean rates of denitrification ranged from -2.76 to 84.0 ng N(2)O-N cm(-3) h(-1) (equivalent to -150 to 4800 microg N(2)O-N m(-2) h(-1)) using an ex situ core technique and from -8.30 to 5.98 microg N(2)O-N m(-2) h(-1) using an in situ chamber technique. Core rates may have been elevated over natural field levels due to effects of disturbance on substrate availability, and chamber rates may have been low due to diffusional constraints on acetylene and N(2)O. Net nitrification was also measured in an attempt to evaluate this process as a source of nitrate for denitrifiers. The low rates of net nitrification measured, in combination with the low rates of in situ denitrification and the very low amounts of free nitrate measured in this peatland, suggests that inorganic N turnover in this wetland is low. Results showed that nitrate was a limiting factor for denitrification in this peatland, with mean rates from nitrate-amended cores ranging from 13.1 to 260 ng N(2)O-N cm(-3) h(-1), and it is expected that increases in nitrogen loadings will increase denitrification rates in this ecosystem.     

Selective dissolution of critical metals from diesel and naptha spent hydrodesulphurization catalysts

The petroleum refining industry makes extensive use of catalysts, containing critical metals, such as, Mo, Co and Ni, for the desulphurization of various oil fractions. The selective recovery of these metals from two uncrushed and at low temperature calcined industrial hydrodesulphurization (Mo---Co/Al₂O₃ and Mo---Ni/Al₂O₃---SiO₂) catalysts was studied, applying a two-step alkali-acid procedure. Fundamental kinetic aspects of the process, such as, reaction time, leaching reagents concentration and reaction temperature, were studied. Recoveries up to 97% for Mo and up to 92% for Co or Ni in separate solutions were achieved, using low cost and easily available reagents, such as sodium hydroxide and sulphuric acid.