圆板型多孔α-Al2O3陶瓷膜支撑体的制备与表征

以α-Al2O3为骨料,羧甲基纤维素作为成孔剂,高岭土、TiO2作为高温粘结剂和烧结助剂,采用干压成型工艺和固态粒子烧结法制备出了圆板型多孔α-Al2O3陶瓷膜支撑体(=50 mm,厚度为2 mm)。研究了成孔剂用量、高温粘结剂和烧结助剂的用量、烧结温度因素对支撑体性能的影响。结果表明,制得的支撑体孔隙率在34%以上,孔径在2.23～6.75μm,耐酸碱度在98%以上,机械强度高。     

Identification of surfactants emerged in aerobic granulation

In this study, aerobic granules were cultivated in sequencing batch reactors with activated sludge as the seed. The reactors were operated for 12 h per cycle with the organic loading rate (OLR) increasing in double stepwise from 0.5 to 4.0 g COD L⁻¹ d⁻¹. Within the 40 d running, black granules with regular and smooth morphology were cultivated, which had high wet density and high settling velocity. During the granulation process, foams emerged and disappeared in the reactor, coinciding with the proliferation of filamentous microorganisms in the granules, implying that surfactants might exist and play an important role in the granulation. Using ultra performance liquid chromatography-tandem mass spectrometry, the surfactants were identified as homologous compounds of polyethylene glycol (PEG) with molecular weights ranging mainly from 100 to 500 Da. Their general formulas were proposed as HO-[CH₂-CH₂-O]_n-H. The source of PEG still needs further investigation.     

Thermal removal of PCDD/Fs from medical waste incineration fly ash--effect of temperature and nitrogen flow rate

The fly ash used in this study was collected from a bag filter in a medical waste rotary kiln incineration system, using lime and activated carbon injection followed by their collection as mixed fly ash. Experiments were conducted on fly ash in a quartz tube, heated in a laboratory-scale horizontal tube furnace, in order to study the effect of temperature and nitrogen flow rate on the removal of PCDD/Fs. Results indicated that in this study PCDD/Fs in the fly ash mostly were removed and desorbed very little into the flue gas under thermal treatment especially when the heating temperature was higher than 350 °C, and dechlorination and destruction reactions took important part in the removal of PCDD/Fs. However, in terms of flow rate, when flow rate was higher than 4 cm s⁻¹, destruction efficiency of PCDD/Fs decreased dramatically and the main contributors were P₅CDF, H₆CDF and H₇CDF desorbed to flue gas, the PCDD/Fs in the fly ash decreased with enhanced flow rate.     

粗MnSO4溶液中MnS2O6的去除条件研究

用软锰矿吸收SO₂生成MnSO₄时会伴随有副产物MnS₂O₆生成。产品中MnS₂O₆的存在会降低硫酸锰产品质量,同时会缓慢释放出SO₂气体污染环境。本文用单因素实验方法研究了粗MnSO₄溶液中MnS₂O₆的最优去除条件。研究结果显示,软锰矿用量为12.2 g,硫酸加入量为20 mL、反应温度100℃、反应时间3 h、搅拌速度500 r/min,MnS₂O₆的去除率可达91%以上。其最终产品能达到GB1622-1986一级品标准。     

Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans in ambient air of different regions in China

Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were determined in fourteen ambient air samples collected in twelve cities of five provinces and one large municipality in China. The PCDD/F concentrations varied from 2.6 to 120 pg m⁻³ (or from 0.04 to 1.93 pg I-TEQ m⁻³). Generally, TCDF was the dominant homologue group and as a rule the homologue concentration of PCDF decreased with rising chlorine substitution number of PCDF. In all cases 2,3,4,7,8-PeCDF was the most important contributor to the I-TEQ value, accounting for 35–57% of the total I-TEQ value. Higher PCDD/F levels in ambient air were found during winter. The highest PCDD/F levels were found in Chengdu, Sichuan Province. In general, the PCDD/F levels in this study were in the same range as in other studies in China.     

沸石生物联合吸附再生工艺中溶解性有机物的特性变化

利用三维荧光技术(EEM)和凝胶过滤色谱法(GFC)研究了沸石生物联合吸附再生(ZCS)工艺中溶解性有机物(DOM)在系统中的变化规律.结果表明,生活污水DOM中主要的荧光物质有类蛋白质(荧光峰A和B)和类腐殖质(荧光峰C),经ZCS工艺处理后,荧光峰B较峰A的强度降低更多,说明类蛋白质的组成结构发生了变化;荧光峰C削...     

H3PMo12O40/活性白土UV - H2O2催化氧化降解甲基橙

采用浸渍吸附法制备了H3PMo12O40/活性白土催化剂,并考察了H3 PMo12O40/活性白土对偶氮染料甲基橙的UV-H2O2降解的催化性能.实验结果表明,当H2O2加入量为0.4 mol/L、H3PMo12O40/活性白土加入量为0.30 g/L、溶液初始pH为2、反应温度为70℃、反应时间为1.0h时,甲基橙去...     

微波改性锆-铝柱撑膨润土对水中Cr(Ⅵ)的吸附

以膨润土为原料,通过微波辐射加热法制备锆-铝柱撑膨润土(MZAPB)吸附剂,研究了 MZAPB 加入量、溶液 pH、吸附时间、温度等因素对 Cr(Ⅵ)吸附效果的影响.研究结果表明:当溶液初始 Cr(Ⅵ)质量浓度为 25mg/L、MZAPB 加入量为 10 g/L、溶液 pH 为 5.6、吸附温度 25℃、吸附时间为 6...     

Persistent organic pollutant emissions from medical waste incinerators in China

The huge amount of medical waste (MW) has caused a tough challenge to environmental protection in China because of its serious infectious potential. At present, incineration is the most common technology for MW disposal. Unfortunately, the medical waste incinerator (MWI) is considered one of the major sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study was conducted to investigate the generation and the components of MW; the fingerprint of PCDD/Fs in MWI; and PCDD/F, polychlorinated biphenyl (PCB) and hexachlorobenzene concentrations in residue ash. The estimated annual production of MW was estimated to be 0.97 million tons in China in 2008; in addition, plastic and rubber accounted for 24.5% of MW contents. PCDD/F emissions from MWI could be divided into two main groups according their fingerprints, and the ratio of PCDFs/PCDDs was mostly over 1.5, with a mean value of 3.43. The toxic equivalent of PCDD/Fs was over 30 times that of the value of PCBs in the residue ash, and PCDD/F contents in fly ash accounted for approximately 67% of the total output of PCDD/Fs, which was in line with the UNEP default emission factors for MWI (class 3, 63.7%).     

A Modal Approach to Vehicular Emissions and Fuel Consumption Model Development

Abstract

This study reports on the analysis of emissions and fuel consumption from motor vehicles using a modal approach. The four standard driving modes are idling, accelerating, cruising, and decelerating. On‐road data were collected using instrumented test vehicles traveling many times through the urban areas of Hong Kong. A model was developed for estimating vehicular fuel consumption and emissions as a function of instantaneous speed and driving mode. Piecewise interpolation functions were proposed for each nonidling driving mode. Idling emission and fuel consumption rates were estimated as negative exponential functions of idling time. Preliminary modeling results showed good agreements for the test vehicles and indicated that the on‐road measurements are feasible for the development of modal emission and fuel consumption models.