Emergy analysis of the recycling options for construction and demolition waste

Construction and demolition (C&D) waste is becoming a major contributor to environmental pollution. In Shanghai, China, the quantity of C&D waste is 2.11E+07 t/yr, which accounts for 45% of the total quantity of solid waste. There has been a growing promotion of recycling C&D waste as an effective way to solve this waste problem. However, the evaluation of the efficiency of recycling C&D waste as a potential source of resources is largely based on traditional economic analysis. The economic analysis emphasizes money instead of the harmony between economic benefit and environmental effects. There is a need for a new strategic approach to investigate the efficiency of recycling C&D waste to achieve the integration between economic, social and environmental effects. Emergy theory can be employed to analyze different recycling options for C&D waste. With reference to the Chinese construction industry, this paper demonstrates that the close-loop recycling option is better than the open-loop recycling option for C&D waste in terms of the integration of social, environmental and sustainable aspects. To evaluate different technology solutions for C&D waste recycling, the emergy theory and method is not limited to a cost-benefit balance but can include economic, social, environmental and sustainable effects.     

Health risk assessment of heavy metals in Cyprinus carpio (Cyprinidae) from the upper Mekong River

The purposes of this research are to quantify the concentration of heavy metals (Zn, Cu, As, Pb, Cd, and Hg) in the water and fish tissues of common carp (Cyprinus carpio) in the upper Mekong River and to thereby elucidate the potential dietary health risks from fish consumption of local residents. Surface water and fish tissues (gill, muscle, liver, and intestine) from four representative sample areas (influence by a cascade of four dams) along the river were analyzed for heavy metal concentrations. Results revealed that the levels of heavy metals in fish were tissue-dependent. The highest Cu and As levels were found in the liver; the highest Zn and Pb levels occurred in the intestine, and the highest Hg level was found in the muscle. The total target hazard quotient (THQ) value for residents is > 1 for long-term fish consumption, and local residents are, therefore, exposed to a significant health risk. Results from the current study provide an overall understanding of the spatial and tissue distribution of heavy metals in water and fish body along the upper Mekong River under the influence of cascade dams and highlight the potential health risk of As for the local residents of long-term fish consumption.

     

TiO2载体对Mn-Ce/TiO2催化剂脱硝活性的影响

以TiO₂为载体,选取过渡金属元素Mn为活性组分,稀土金属元素Ce为活性助剂,采用分步共混法制备了Mn-Ce/TiO₂催化剂（活性组分负载量16%）,系统研究了TiO₂载体的晶型和晶粒尺寸对催化剂脱硝活性的影响。实验结果表明：分别以锐钛矿型和金红石型TiO₂为载体制备的催化剂,其低温脱硝活性相差不大,活性组分均以无定型态高度分散于载体中,以金红石型TiO₂为载体制备的催化剂中部分TiO₂转变为锐钛矿型;以不同晶粒尺寸TiO₂载体制备的催化剂的低温脱硝活性相差较大,比表面积较大、晶粒尺寸较小的TiO₂载体制备的催化剂,其脱硝活性低于晶粒尺寸较大的TiO₂载体制备的催化剂。     

Preparation of biochar catalyst with saccharide and lignocellulose residues of corncob degradation for corncob hydrolysis into furfural

This paper presented a novel process for production of furfural by hydrothermal degradation of corncob over biochar catalyst, in which it was prepared with the recycling degradation solution and lignocellulosic solid residues. The biochar catalyst was papered by lignocellulose residues and concentrated saccharide solution, and then impregnated in 0.5 mol/L sulphuric acid at room temperature for 24 h assisted by the ultrasonic vibration. In the system of recycling, 8.8 % lignocellulose residues and 100 % concentrated saccharide solution from corncob hydrolysis have been recycled. Hydrolysis of corncob was carried out at 180 °C for duration of 170 min over the biochar catalyst. The experimental results have shown that the furfural yield of up to 37.75 % and overall corncob conversion rate of 62.00 % could be achieved under optimum operating conditions for the catalysts preparation and the corncob hydrolysis. It is believed that the acid density of 4.27 mmol/g of biochar catalyst makes the SO₃H groups cleave β-1,4 glycosidic linkages effectively and hydrolyze the cellulose and hemicellulose to water-soluble sugars, as well as to facilitate dehydration of xylose to give the product of furfural.     

工业烟气氨法-络合法同时脱硫脱硝

在脱硫脱硝喷淋装置上采用氨法-络合法处理工业烟气。考察了吸收液pH、Fe(Ⅱ)EDTA浓度、初始烟气浓度、液气比对烟气同时脱硫脱硝效果的影响。实验结果表明:吸收液的酸碱度通过影响Fe(Ⅱ)与EDTA的络合形式进而影响NO去除率;SO_2去除率主要受吸收液pH和初始SO_2质量浓度的影响;当吸收液pH大于8、吸收液Fe(Ⅱ)EDTA浓度大于0.100 mol/L、初始SO_2质量浓度小于1 500 mg/m3、初始NO质量浓度为1 200 mg/m3时,SO_2去除率均在95%以上,NO去除率为54%;当液气比由1 L/m3增大至4 L/m3时,有效脱硫时间和有效脱硝时间分别增长了7 min和4 min。     

PbO_2复合电极预处理甲苯二胺废水

通过涂覆—热分解法与电沉积法制备了β-PbO_2/α-PbO_2/SnO_2-Sb2O3/Ti复合电极(PbO_2复合电极),采用X射线衍射(XRD)、扫描电子显微镜(SEM)、循环伏安法(CV)、线性极化法(LSV)和加速寿命试验对电极进行表征。将PbO_2复合电极用于处理甲苯二胺(TDA)废水,考察了电解质浓度、电流密度对TDA降解效果的影响。实验结果表明:α-PbO_2呈梭状,β-PbO_2呈花菜状,多层结构的PbO_2电极利于提高电极的稳定性和活性;PbO_2复合电极的析氧电位(1.9 V)明显高于TDA的氧化电位(1.28 V),其使用寿命长达486 d;在电流密度为60 m A/cm2、Na2SO4质量浓度为10 g/L、电解时间为240 min的条件下,对COD为4 791.74 mg/L、TDA质量浓度为486.4mg/L的废水进行处理,TDA去除率高达97.3%,COD去除率可达88.1%。     

Suppression of precipitation by dust particles originated in the Tibetan Plateau

Dust aerosols play an important role in modulating the hydrologic cycle. The Tibetan Plateau (TP) is little polluted by human activities as an ideal site to study the effect of dust aerosol on precipitation. In this study, observational data of dust storms and precipitation in the TP and its vicinities as well as CALIPSO satellite data were used to analyze the distributions and vertical structure of dust storms on the plateau. The results showed that dust storms occur with high frequency and raise dust particles into the troposphere from ground level to a height of 5–9 km to modulate the hydrologic cycle in the TP. There are significant negative correlations between dust aerosol and precipitation in the dust source regions during the period of both 40 and 200 years. It is found that the role of precipitation in suppressing dust storms could be unimportant, while dust aerosol may play an important role in suppressing precipitation in the hinterland of the TP. Our study provides a potential approach to better understand the climate changes in the TP.     

Effect of typhoon on atmospheric particulates in autumn in central Taiwan

Previous studies have suggested that the ongoing global climate change will likely increase the intensity and frequency of extreme weather, such as typhoons. Since the beginning of global warming, it has become necessary to understand the influence of typhoons on air quality. Rare data, especially particulate measurements data could be used to establish the relationship between the air pollution and typhoons. One of main limiting factors is that most of the previous chemical analyses of particulates used a relatively long sampling time, which could dilute the temporal impact of particulate characteristics and their sources. This work, depending more time-resolved measurements, focus on the characteristics and sources of high particulate matter levels and the influence of typhoons and the Pacific high system. Depending on the measurements, two pollutant groups were clearly identified in this work. The first pollutant group was the emissions from neighboring riverbeds under the strong circulation of the typhoon in the driest season and characterized as high coarse particle concentrations with high mass fraction of Ca²⁺. The second pollutant group was characterized as the formation and transport of secondary particles with prevalent ions of NH₄⁺, NO₃^?, and SO₄^2? and occurred in the sea-land breeze circulation under the influence the Pacific high system.     

DO对好氧颗粒污泥短程同步硝化反硝化脱氮的影响

以模拟城市污水为处理对象,研究了不同溶解氧下序批式活性污泥反应器（SBR）的短程同步硝化反硝化过程特征及处理效果。试验结果表明,溶解氧浓度是实现短程同步硝化反硝化的一个重要控制参数。在亚氮积累阶段,控制温度为28～32℃,pH值为7.5～7.8,当进水NH⁺₄-N为30 mg/L左右,COD为250 mg/L左右时,亚硝酸盐氮的积累率达到96%～98%。在试验阶段,常温下控制溶解氧在0.5～1.0 mg/L,可保证氨氮的去除率达到95%～97%,总氮的去除率达到82%～85%。     

SBR降解动力学研究

采用SBR工艺处理有机废水,在已有工艺条件下对生物降解动力学进行了研究,得出生物降解反应为一级反应。研究表明,用Monod公式能较好反映出有机物的降解规律,确定了其动力学参数V_max=14.6306 d^-1,K_s=83.2993 mg/L,得出SBR降解动力学模型为V=14.6306X·S/(83.2993+S)。利用以动力学为基础的动态模拟法优化SBR工艺,实验结果表明该方法合理可行,对SBR的设计与运行有一定的指导作用,可作为SBR反应器扩大实验和设计的依据。