公交车基于不同燃油的实际道路排放性与燃油经济性

使用便携式车载排放测试系统测试了2辆国VI公交车和2辆国III公交车燃用不同燃料的实际道路排放特性和经济性.结果表明,相比于燃用京VI车用柴油,国VI公交车燃用B5生物柴油(柴油中掺混5%生物柴油)的CO比排放降低了33.1%,NO_x比排放增加了15.6%,颗粒物数量(PN)比排放降低了13.1%.4辆公交车燃用B5生物柴油的CO排放因子较京VI车用柴油平均降低了29.5%,NO_x排放因子增加了12.7%,PN排放因子降低了9.1%.通过对CO_2的分析发现,燃用B5生物柴油的排放因子较燃用京VI车用柴油增加了11.3%,运用碳平衡计算方法计算油耗,并考虑燃油密度的影响,结果发现,燃用B5生物柴油的百公里油耗较燃用京VI车用柴油增加了11.51%,相差较大,后续需深入研究油品热值等其他理化指标对燃油经济性的影响.     

北京市压缩天然气公交车的环境效果分析

经过对北京市2007年公交车队的详细技术构成与实际运营情况的调研,发现北京市公交车队的主力车型为国三和国四车辆,应用修正的COPERTIV模型计算出北京市各技术水平的汽油、柴油和压缩天然气(CNG)公交车的排放因子.2007年北京市国三CNG公交车PM2.5和NOx单车排放因子分别比国三柴油车削减了97%和30%,而公交车队中排放控制最为严格的EEV天然气公交车的PM2.5和NOx单车排放因子分别比国四柴油公交车削减了93%和69%.但由于CNG公交车的CH4排放水平较高,导致CNG公交车的总碳氢化合物(THC)单车排放因子显著高于相近控制水平的柴油公交车.在单车排放水平的基础上建立了北京市公交车排放清单,2007年北京市公交车排放的CO、NMHC、THC、NOx和PM2.5分别为9051t、955t、1222t、8553t和161t.与没有CNG公交车的对照情景进行比较,在使用了CNG公交车后,2007年北京市公交车CO、NMHC、NOx和PM2.5排放总量分别削减了293t、62t、775t和33t,削减比例分别为3.1%、6.1%、8.3%和17.2%.2007年北京市通过在公交车队中使用CNG车辆共减少了柴油消耗量约5.0×104t,相当于北京市各行业柴油总消耗量的2.6%.2007年北京市公交车尾气排放的温室气体的CO2当量为8.3×105t,比不使用CNG车辆的情景略微增加了2.4%.     

基于DOC+CDPF技术的公交车燃用生物柴油气态物道路排放特性

基于OBS-2200车载排放检测系统,试验研究并分析了催化型连续再生颗粒捕集器(DOC+CDPF)及生物柴油混合燃料B20(生物柴油体积占比20%)对国Ⅲ柴油公交车瞬态工况和稳态工况下气态物道路排放特性的影响.结果表明相较于B0(纯柴油),B20的一氧化碳(CO)、总碳氢化合物(THC)平均排放率偏低,其中,稳态工况下降幅分别为26.43%、10.44%,瞬态工况下降幅分别为22.78%、4.95%;二氧化碳(CO_2)和氮氧化物(NO_x)平均排放率偏高,其中,稳态工况下分别上升8.41%和8.26%,瞬态工况下分别上升7.15%、9.13%.相较于B0,DOC+CDPF对B20的CO和THC净化效果更为显著,其中,稳态工况下降幅分别达60.58%和79.92%,瞬态工况下,降幅分别达63.67%和82.57%.DOC+CDPF使用后,CO_2和NO_x的排放率略微下降.     

在用国Ⅲ/国Ⅳ/国Ⅴ柴油公交车的颗粒物质量及固态PM2.5数量排放特性

利用法规认证全流稀释定容采样系统以及满足精度要求的颗粒物排放分析系统,运行GB/T 19754—2005《重型混合动力电动汽车能量消耗量试验方法》推荐的中国典型城市公交循环(CCBC),分析了在用国Ⅲ/国Ⅳ/国Ⅴ柴油公交车以及在用国Ⅲ柴油公交车进行DOC(氧化催化转化器)+CDPF(催化型颗粒捕集器)改造后的颗粒物质量、固态PM_2.5数量排放特性.结果表明:国Ⅲ、国Ⅳ、国Ⅴ柴油公交车的颗粒物质量排放因子分别为63.77、63.20和14.42 mg/km,固态PM_2.5数量排放因子分别为3.87×1013、3.10×1013和2.77×1013 km-1.与国Ⅲ柴油公交车相比,国Ⅳ柴油公交车的颗粒物质量、固态PM_2.5数量排放因子分别降低了1%和20%;国Ⅴ柴油公交车分别降低了77%和28%;进行DOC+CDPF改造的国Ⅲ公交车颗粒物质量、固态PM_2.5颗粒数量排放因子分别为1.78 mg/km和3.19×1011 km-1,比未改造前分别降低了97%和99%.中国典型城市公交循环的低速(0～21.8 km/h)、中低速(0～37.5 km/h)、中高速(0～51.7 km/h)和高速(0～60.0 km/h)4类行驶工况中,低速行驶工况的固态PM_2.5数量排放因子最高,约是整个循环的2倍;在加速、匀速、减速、怠速4种行驶模式中,加速行驶模式产生的固态PM_2.5单位时间排放量最高,其分别为减速和怠速行驶模式下的10和6倍.研究显示,提高柴油公交车的平均车速,降低加速行驶比例有利于降低其颗粒物排放;DOC+CDPF可显著降低国Ⅲ柴油公交车的颗粒物排放.      

BED含氧燃料在不同海拔下对柴油机PM和NOx排放的影响

为研究生物柴油-乙醇-柴油(简称为BED)含氧燃料在不同海拔下对柴油机微粒(PM)和氮氧化物(NO_x)排放的影响,在一台高压共轨柴油机上分别燃用纯柴油和BED含氧燃料,在两种大气压力(81和100 k Pa)下进行了排放试验研究.结果表明,燃用纯柴油和B15E5(15%生物柴油+5%乙醇+80%柴油,体积比)燃料后,在中、低负荷时的PM排放在高气压下基本高于低气压下,最高增幅分别达到26.2%和19.0%;在全负荷时的PM排放在高气压下降低,最高降幅分别达到6.1%和17.0%.燃用B25E5(25%生物柴油+5%乙醇+70%柴油,体积比)燃料后,PM排放在高气压下降低.燃用纯柴油后,柴油机在高气压下的NO_x排放低于低气压下;燃用B15E5和B25E5含氧燃料后,在中、低负荷下的NO_x排放在高气压下降低,在全负荷下的NO_x排放在高气压下升高.在中、低负荷下NO_x排放最高降幅分别达到12.1%和15.3%;在全负荷下,NO_x排放最高增幅分别达到6.5%和5.8%.在不同大气压力下,柴油机燃用纯柴油和BED含氧燃料后,PM与NO_x排放均呈现明显的trade-off关系.相比于在低气压下,随负荷增加引起的PM排放降幅和NO_x排放增幅在高气压下增加.     

乙醇汽油对国六直喷汽油车排放特性的影响

选择5台国六直喷汽油车采用3种不同组分的E10乙醇汽油和1种不含含氧化合物的国VI汽油,按照国六排放标准开展了WLTC循环测试,研究乙醇和基础油组分对污染物排放的影响规律.结果表明,多数国六直喷汽油车的CO、THC和PM排放有所降低,NO_x排放无明显差异,PN排放微增,所有样车的CO、THC和PM平均排放降低为6%、7%和14%.E10乙醇汽油中的重质芳香烃含量增高时,PN排放明显增加,PN排放与PMI指数呈现较强的正相关关系.     

乙醇汽油对国六直喷汽油车排放特性的影响

选择5台国六直喷汽油车采用3种不同组分的E10乙醇汽油和1种不含含氧化合物的国VI汽油，按照国六排放标准开展了WLTC循环测试，研究乙醇和基础油组分对污染物排放的影响规律.结果表明，多数国六直喷汽油车的CO、THC和PM排放有所降低，NO_x排放无明显差异，PN排放微增，所有样车的CO、THC和PM平均排放降低为6%、7%和14%.E10乙醇汽油中的重质芳香烃含量增高时，PN排放明显增加，PN排放与PMI指数呈现较强的正相关关系.     

国Ⅴ公交车燃用生物柴油的颗粒物碳质组分排放特性

以一辆国Ⅴ柴油公交车为研究对象,在重型底盘测功机上运行中国典型城市公交循环,研究了纯柴油（D100）,体积混合比例分别为5%,10%和20%餐厨废弃油脂制生物柴油-柴油混合燃料（即B5,B10,B20）的颗粒物（PM）碳质组分排放特性.结果表明：国Ⅴ柴油公交车尾气颗粒物碳质组分包括有机碳（OC）和元素碳（EC）,OC占73%~82%,OC的主要组分是OC2和OC3,生物柴油对车辆尾气颗粒物OC组成比例没有影响;随着生物柴油混合比例的增加,公交车尾气颗粒物OC和OC+EC排放呈降低的趋势,EC排放增加,且B10的OC排放较高;PM_0.05~0.1,PM_0.1~0.5,PM_0.5~2.5,PM_2.5~18 4个粒径段颗粒物中,PM_0.1~0.5的OC和EC排放最高,PM_2.5~18的EC排放几乎为零,生物柴油可改善公交车尾气超细颗粒（PM_0.05~0.1）的OC排放,对公交尾气颗粒物EC排放基本没有影响;公交使用生物柴油混合燃料尾气颗粒物OC/EC减小,且PM_0.05~0.1和PM_0.5~2.5OC/EC降低幅度明显,对大气二次气溶胶的影响减弱.     

船舶燃用B10餐厨废弃油脂制生物柴油排放测试与分析

利用便携式排放测试系统（PEMS）,对一艘内河船舶燃用B10餐厨废弃油脂制生物柴油（生物柴油:柴油为1:9,体积比）进行实际工况排放测试。出港和进港工况下,CO、THC、NO_x和PM瞬态排放速率波动明显,巡航工况下,CO、THC和PM瞬态排放速率较稳定,NO_x排放随空气流量变化而在一定范围内波动;同燃用纯柴油时气态物和颗粒物排放相比,船舶燃用B10生物柴油时,在出港、巡航和进港工况,CO排放速率下降了20.37%、24.39%和6.05%,THC下降了8.2%、8.13%和25.23%,PM下降了53.11%、22.38%和36.55%,PN下降了14.17%、18.75%和46.47%;在出港和进港工况,NO_x排放速率下降了54.28%和40.39%,在巡航工况,NO_x上升了10.45%;燃用2种燃油排放颗粒物均随粒径呈双峰分布,峰值粒径大致相同,燃用B10生物柴油时核态颗粒物数量下降明显。试验表明,船舶燃用B10生物柴油能有效降低气态物和颗粒物排放。     

DOC/CCRT老化对柴油公交车气态物排放特性的影响

基于重型底盘测功机,研究新鲜及老化氧化型催化器(DOC)、氧化型催化器耦合催化型颗粒捕集器(DOC+CDPF,CCRT)对在用国Ⅲ柴油公交车进行中国典型城市公交车循环CCBC时一氧化碳(CO)、总碳氢化合物(THC)、一氧化氮(NO)、二氧化氮(NO_2)和氮氧化物(NO_x)、二氧化碳(CO_2)等气态物排放特性的影响.结果表明:采用新鲜及老化DOC/CCRT,均可以降低CO、THC、NO排放,增加NO_2排放,NO_x及CO_2排放基本不变;在怠速、加速、减速及匀速这4种工况下,新鲜DOC比老化DOC对CO、THC氧化效率好,新鲜CCRT比老化CCRT对THC氧化效率好,但老化CCRT对CO氧化效率更好,新鲜DOC/CCRT比老化DOC/CCRT对NO减少幅度高,对NO_2增加幅度高,但对NO_x排放总量基本无影响.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.