双氯芬酸的吸附去除过程与机制

研究了非甾体抗炎药双氯芬酸的吸附去除过程与机制。对吸附处理效果较好的活性炭与纳米羟基氧化铁（α-FeOOH）进行了比表面积、Zeta电位等表面特性的表征,研究比较了双氯芬酸在活性炭与α—FeOOH2种材料上的吸附去除效果与吸附机制。结果表明,在相同的实验条件下,活性炭与α-FeOOH对双氯芬酸吸附去除率可分别达到97．9％和84．3％;双氯芬酸在活性炭上的吸附主要是由于活性炭较大的比表面积与疏水分配作用,在α-FeOOH上的吸附主要是由于静电引力作用;活性炭与α-FeOOH对双氯芬酸的吸附去除效果均随pH的升高而降低;在pH=6时,活性炭与α-FeOOH对双氯芬酸钠的吸附等温线均符合Langmuir方程,单位饱和吸附量分别为109．98mg／g和58．96mg／g;活性炭对双氯芬酸具有更强的吸附能力。     

Characterization of polychlorinated naphthalenes in stack gas emissions from waste incinerators

Nine typical waste incinerating plants were investigated for polychlorinated naphthalene (PCN) contents in their stack gas. The incinerators investigated include those used to incinerate municipal solid, aviation, medical, and hazardous wastes including those encountered in cement kilns. PCNs were qualified and quantified by isotope dilution high resolution gas chromatography–high resolution mass spectrometry techniques. An unexpectedly high concentration of PCNs (13,000 ng?Nm^?3) was found in the stack gas emitted from one waste incinerator. The PCN concentrations ranged from 97.6 to 874 ng?Nm^?3 in the other waste incinerators. The PCN profiles were dominated by lower chlorinated homologues, with mono- to tetra-CNs being the main homologues present. Furthermore, the relationships between PCNs and other unintentional persistent organic pollutants involving polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, hexachlorobenzene, and pentachlorobenzene were examined to ascertain the closeness or otherwise of their formation mechanisms. A good correlation was observed between ΣPCN (tetra- to octa-CN) and ΣPCDF (tetra- to octa-CDF) concentrations suggesting that a close relationship may exist between their formation mechanisms. The results would provide an improved understanding of PCN emissions from waste incinerators.     

Study of PCDD/Fs distribution in fly ash,ash deposits,and bottom ash from a medical waste incinerator in China

Over the past decades in China, the number of medical waste incinerators (MWIs) has been rising rapidly, causing emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). In this study, samples of fly ash, ash deposits, and bottom ash from typical MWIs were analyzed for PCDD/Fs and their distribution characteristics. Results showed international toxic equivalent (I-TEQ) values in the range of 6.9–67 ng I-TEQ/g in fly ash and ash deposits, whereas the concentration in bottom ash was extremely low (only 1.33 pg I-TEQ/g), yet the generation of PCDD/Fs was mostly de novo synthesis in fly ash and ash deposits according to the ratio of PCDFs to PCDDs; the major distribution differences of PCDD/Fs in fly ash was manifested by the content of toxic furan 2,3,7,8-TCDF, but other toxic PCDD/Fs showed similar distribution. Other findings are that 2,3,4,7,8-PeCDF had the most contribution to TEQ concentration, and that the most abundant toxic furan congener is 1,2,3,4,6,7,8-HpCDF. Correlation analysis showed that there was no significant correlation between PCDD/Fs concentration and several other physical and chemical parameters.

Implications: This paper is of interest because it presents the emission performances of PCDD/Fs in ash from medical waste incineration in China. PCDD/F contents in fly ash and ash deposits vary between 6.9 and 67.3 ng I-TEQ/g. However, the concentration in bottom ash was extremely low (only 1.33?×?10^?3 ng I-TEQ/g). The fingerprints of PCDD/Fs in fly ash are almost similar, except for 2,3,7,8-TCDF. There is no marked correlation between PCDD/Fs and other physicochemical properties.

Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association.     

Airborne bacterial reduction by spraying slightly acidic electrolyzed water in a laying-hen house

Spraying slightly acidic electrolyzed water (SAEW) has been considered as a potential approach to reduce airborne bacteria in laying-hen houses. In this study, the effects of spraying SAEW on airborne bacterial reduction were investigated in a laying-hen house as compared with using diluted didecyl dimethyl ammonium bromide (DDAB). Averaged air temperature reduced by approximate 1 °C and average relative humidity increased by 3% at a stable ventilation rate (about 2.5 m³ hr^?1 per bird) in the laying-hen house 30 min after spraying (120 mL m^?2). Compared with the control without spraying, the airborne bacterial concentration was reduced by about 0.70 and 0.37 log₁₀ colony-forming units (CFU) m^?3 in the 4 hr after spraying 120 mL m^?2 SAEW (available chlorine concentration [ACC] of 156 mg L^?1) and diluted DDAB (active compound concentration of 167 mg L^?1), respectively. Compared with spraying diluted DDAB, spraying SAEW was determined to be more effective for reducing airborne bacterial in laying-hen houses. The effects of spraying SAEW and diluted DDAB on airborne bacterial reduction in the laying-hen house increased with the increasing available chlorine concentrations for SAEW (156, 206, 262 mg L^?1) and increasing active compound concentrations for diluted DDAB (167, 333, 500 mg L^?1), respectively. Spraying SAEW and diluted DDAB with two levels of spraying volumes (120 and 90 mL m^?2) both showed significant differences on airborne bacterial reduction in the laying-hen house (P < 0.05).

Implications: It is difficult to effectively reduce airborne bacteria in laying-hen houses. This work describes the application of spraying slightly acidic electrolyzed water as a new approach for reducing airborne bacteria in a laying-hen house. The effects of active compound concentrations and spray volumes on the airborne bacterial reductions by spraying SAEW were also investigated. This study provided a new effective and environmentally friendly approach to reduce the airborne bacteria in poultry houses, contributing to bird housing environment management and improving bird health.     

A general method for evaluating the effects of air pollutants on lung cancer prevalence

ABSTRACT

It is widely accepted that some air pollutants are related to lung cancer prevalence. An effective method is proposed to quantitatively evaluate the effects of air pollutants and the interactions between them. The method consisted of three parts: data decomposition, comparable data generation and relationship inference. Firstly, very limited monitoring data published by Geographic Information System were applied to calculate the inhalable air pollution of relatively massive patient samples. Then the investigated area was partitioned into a number of districts, and the comparable data containing air pollutant concentrations and lung cancer prevalence in all districts were generated. Finally, the relationships between pollutants and lung cancer prevalence were concluded by an information fusion tool: Choquet integral. As an example, the proposed method was applied in the investigation of air pollution in Tianjin, China. Overall, SO₂, O₃ and PM_2.5 were the top three factors for lung cancer. And there was obvious positive interaction between O₃ and PM_2.5 and negative interaction among SO₂, O₃ and PM₁₀. The effect of SO₂ on men was larger than on women. O₃ and SO₂ were the most important factors for the adenocarcinoma and squamous cell carcinoma, respectively. The effect of SO₂ or NO₂ on squamous cell carcinoma is obviously larger than that on adenocarcinoma, while the effect of O₃ or PM_2.5 on adenocarcinoma is obviously larger than that on squamous cell carcinoma. The results provide important suggestions for management of pollutants and improvement of environmental quality. The proposed method without any parameter is general and easily realized, and it sets the foundation for further researches in other cities/countries.

Implications: For total lung cancer prevalence, male and female lung cancer prevalence, and adenocarcinoma and squamous cell carcinoma prevalence, the proposed method not only quantify the effect of single pollutant (SO₂, NO₂, CO, O₃, PM_2.5, and PM₁₀) but also reveals the correlations between different pollutants such as positive interaction or negative interaction. The proposed method without any geographic predictor and parameter is much easier to realize, and it sets the foundation for further research in other cities/countries. The study results provide important suggestions for the targeted management of different pollutants and the improvement of human lung health.     

特殊植物类群空气凤梨对大气污染物甲醛的净化

空气凤梨是一类生长在空气中、不需要土壤、生长所需的水分和营养可以全部来自空气的特殊植物。它们常被用来指示与修复大气重金属污染物和有机污染物,但尚未应用于甲醛净化研究。为了探讨空气凤梨对甲醛的净化效果,我们以2种空气凤梨为实验材料,吊兰为对照材料,通过密封箱内甲醛熏蒸及在封闭的实际环境中进行了实验。结果表明,松萝铁兰、硬叶空凤和吊兰3种植物在甲醛胁迫下,外部形态和生理指标有一定的变化,但未受到明显的伤害。更重要的是,3种植物对甲醛均有相当强的净化作用。6～8 h后,2种空气凤梨对甲醛的净化可达到与吊兰相近的效果。而在2 h内,空气凤梨净化甲醛的速度远远大于吊兰,这可能是与空气凤梨叶片表面覆盖有亲水性的鳞片层有关。上述结果表明,空气凤梨是比吊兰更快速有效地净化甲醛的植物类群,可选择应用于室内甲醛污染去除。     

基于成本-效能分析的氧化沟工艺运行条件优化

在利用ASM2d模型对城市污水处理厂氧化沟工艺进行动态模拟的基础上,将曝气能耗、污泥产量与出水水质超标率整合为一个综合效能指数,对该工艺进行了成本-效能分析。最优运行策略为:3～10月温度高于15℃时运行8台曝气转刷,其余时间段运行10台转刷,同时剩余污泥排放量控制在250 m3/d。这一策略能够使出水NH4-N和TN的超标率分别低于5%和2%,保证出水TP的持续达标,与常规运行策略相比,在明显降低氮磷超标率的同时,节省曝气能耗约12%。     

磷酸钙盐结晶除磷工艺性能研究

研究了主要工艺条件pH和Ca/P对磷酸钙盐结晶除磷工艺性能的影响。通过分批实验,建立了磷去除率与pH之间的指数函数关系以及磷去除率与Ca/P之间的对数函数关系。连续运试表明,在pH=9.0、Ca/P=2的条件下,磷酸钙盐结晶除磷反应器的容积负荷为1.10 kg P/(m3.d),磷去除率为51%。灵敏度分析表明,pH对磷去除率的影响大于Ca/P,将Ca/P提高至6,容积负荷提高至1.60 kg P/(m3.d),磷去除率提高至74.3%;将pH提高至10.0,容积负荷提高至1.80 kg P/(m3.d),磷去除率提高至83.5%。工艺操作上可选pH作为优先控制对象。     

活性炭-臭氧体系处理含氰废水的作用机理

针对活性炭催化臭氧化降解低质量浓度含氰废水体系,研究了活性炭吸附、催化作用在催化臭氧化体系中的作用,提出了吸附-催化臭氧化协同作用机理。在活性炭-臭氧体系中,活性炭吸附CN-的能力很弱,活性炭在反应体系中主要起了吸附、催化臭氧的作用。活性炭-臭氧体系降解CN-的过程是臭氧直接氧化、活性炭吸附臭氧与活性炭催化臭氧产生.OH自由基间接氧化三者共同作用的结果。     

不同热处理温度对污泥厌氧发酵产氢的影响

污水处理厂污泥产生量日益增加,对环境的影响倍受关注。污泥除了含有大量的葡萄糖、蛋白质等有机物外,还包括大量的微生物,具有厌氧发酵产氢的潜能。通过批式实验系统研究了热处理污泥厌氧发酵产氢情况。研究结果表明,经过适当热处理,可以抑制耗氢菌,同时能保持产氢菌的活性,另外,对污泥还有一定的融胞作用,使污泥中溶解性的糖和蛋白质的含量增加,提高预处理污泥的产氢效率;最佳的热处理温度为75℃,处理后污泥进行厌氧发酵产氢的最大累积产氢量为18.32 mL,比产氢率3.49 mL/g VS。