厌氧消化污泥和未消化污泥在TG-MS上的热化学特性比较

利用热重-质谱联用仪对厌氧消化污泥和未消化污泥的燃烧和热解过程分别进行了研究.结果表明,2种污泥燃烧和热解过程中的热失重行为都可分为失水、有机物分解、无机物分解3个阶段.在300～350℃温度范围内,无论燃烧还是热解过程,未消化污泥有机物分解造成的热失重现象均比厌氧消化污泥明显.无机物分解阶段,厌氧消化污泥主要是碳酸盐的分解,未消化污泥主要是硫酸盐的分解.采用同步质谱仪对热解和燃烧的气态产物进行了分析,结果表明,污泥燃烧和热解过程除了产生大量的H2O和CO2外,热解过程还产生CH4、C2H6、C4H10、C7H8等有机气体以及H2.厌氧消化污泥热解时有机气体产生量小于未消化污泥.     

热分析-质谱联用分析生物垃圾热解机理

采用热分析-质谱联用技术研究了城市生活垃圾中三种生物质成分的热解过程,并采用Freeman-Carroll法定量分析了三种生物质热重动力学参数。结果表明木屑、落叶和菜叶这类生物质热解过程分为三个阶段,先是水分析出的微小失重阶段,之后是因纤维素等大分子进行交联缩聚的快速热解阶段,表现为放热效应,逸出的气体主要有H2O、CO2、C2H6/C2H4和CH4,最后是吸热脱链解聚的缓慢热解过程,逸出的小分子气体主要有CO2。     

微波热解污泥燃气释放影响因素及热解动力学分析

微波热解城市污水污泥可实现污泥资源化、减量化目标。城市污水污泥微波热解后产生大量能源气体H2和CO。运用气相色谱技术检测H2和CO的含量,研究了热解终温、污泥含水率、矿物催化剂对污泥微波热解过程中能源气体产率的影响,结合热重分析对热解过程进行了动力学分析。结果表明:随着热解终温升高,2种燃气产率均有所提高,800℃时,1 kg干污泥产生29.02 g H2以及302.72 g CO,两者体积之和占气体总体积的58%;污泥含水率越高,气体产率越高,但是达到90%含水率时,热解过程无法进行。镍基催化剂和白云石对能源气体产率均有促进作用,800℃时,镍基催化剂可使H2和CO产率提高到60%,对CxHy产率提高效果不明显;利用一级反应动力学方程对污泥热重结果进行分析,计算出热解动力学参数。     

城市污泥两段式催化热解制合成气研究

为了把城市污泥中温热解产生的挥发性产物转化为可直接利用的洁净可燃性气体或重要的化工原料合成气,采用两段式热解装置对城市污泥进行了催化热解实验研究,讨论了不同催化剂对城市污泥热解挥发性产物的催化裂解能力,结果表明:城市污泥在热解终温500℃,热解液产率最大,超过500℃,热解液产率减少,热解气增多,固相产率基本不变;城市污泥热解液的裂解温度需在900℃以上,产生的气体组分主要为H2、CO、CH4等小分子非冷凝性气体;Ni/分子筛复合催化剂对热解液转化为合成气的作用效果较好,合成气体(H2+CO)体积含量占气体总量的85%以上.     

生活垃圾热解产物中含氧物质的分布规律

采用热重分析、固定床实验、红外分析(FT-IR)研究了生活垃圾热解行为及产物中含氧物质的分布规律。用热重分析确定了生活垃圾主要失重区间(190~450℃),并计算此温度区间热解活化能为42.76 k J/mol。在热解终温为450~650℃条件下进行生活垃圾固定床热解实验,结果表明:随热解终温的增加,固体产物中氧分布率逐渐减小(39.2%~29.3%);热解气中氧分布率逐渐增加(22.1%~30.9%);热解液中氧分布率在40%左右。生活垃圾热解气中含氧成分主要是CO和CO2,在温度为450~650℃时,CO含量明显高于CO2,而CO2的释放速率则大于CO;固体产物中含氧官能团主要有—OH和C—O,其中峰面积比例顺序为C—O>—OH;热解液中含氧官能团主要有—OH、C O和C—O,其峰面积的比例顺序为—OH>C—O>C O。     

含厨余垃圾的混合污水污泥热解性能及逸出气体分析

为解决厨余垃圾进入市政管网导致的污泥处理问题,利用厨余垃圾制备初沉污泥(PS),与污水处理的残余污泥(RS)混合制备了不同厨余垃圾比例的混合污水污泥(MSS)。采用TG-FTIR评估了含厨余垃圾的混合污水污泥的热解性能及逸出气体特性。质量损失可分为3个阶段:初步脱水阶段、主要分解阶段及连续轻微分解阶段。PS含量的增加导致反应速率提高和热解特性参数CPI增加,反应时间缩短,从而提高了污水污泥的热解性能。不同温度下PS和RS之间的相互作用存在差异,低温区(<300℃)基本不存在相互作用,中温区(300~550℃)为相互促进,高温区(550~850℃)为相互抑制。FTIR主要检测出CH₄、CO₂、H₂O、CO、CO、SO₂ 6种气态产物及官能团,表明CO₂是主要的气态产物,且随着PS含量的增加,逸出气体及官能团的产生均增加。相互作用不仅体现在质量损失过程中,也体现在产物演化过程中,PS50RS50呈现最明显的相互促进效果,可认为是最适合的比例。随着温度增加,产物普遍在500~600℃内达到最大值,可认为是最佳的热解温度。     

HCl气体对污泥热解产物性质影响的试验研究

为研究污泥热解中同步提升热解产气品质和制取低重金属含量半焦吸附剂,文章分别在800℃和900℃下进行干化后污泥的快速热解实验,对比研究了通入HC(l0.1%体积分数)气体对热解气体产物组分、半焦中重金属含量及制取半焦吸附性能的影响。研究表明热解过程中通入HCl可在提高热解气组分中H2、CO含量的同时提高重金属去除率、降低热解半焦中重金属残余量,增大热解半焦比表面积、提高其吸附性能,但对于半焦吸附性能的影响程度要小于对热解产气及重金属残余量的影响。900℃通入HCl时H2和CO含量均最高分别达到35.01%和30.68%,同时半焦中重金属浓度最低,且同时具有最大比表面积、最高吸附性能,对Pb2+最大吸附量为19.2 mg/g。     

模拟医疗废物在管式电阻炉上的热解特性研究

在管式电阻炉上对由聚丙烯、面巾纸、纱布、医用脱脂棉、一次性口罩、医用乳胶手套等按一定比例组成的模拟医疗废物在氮气气氛进行了热解研究。重点探讨了10K／min，20K／min，30K／min和40K／min等不同升温速率对热解产物分布、产气特性和热解过程的影响。结果表明，随着温度升高，模拟废物的热解产生气体的主要成分逐渐由CO2和CO转变为C3H6、CH4、C2H6、C2H4和C3H8。同时，热解处理对模拟废物的减量化效果比较明显，固体残留率仅为5．61％～7．02％。而且，加热速率对模拟医疗废物热解过程的影响较大。     

活化温度对SCAC制备过程中副产物生成规律的影响

文章研究了污泥-玉米芯活性炭(SCAC)制备过程中,活化温度对副产物(热解气和热解油)生成规律的影响。热解气和热解油分别采用气相色谱仪和气质联用仪进行分析检测。试验结果表明,随着活化温度的升高,SCAC的产量逐渐降低,热解气与热解油的产量则随之增多。不同温度条件下,热解气的主要成分均为H2和CO2,热解气中H2所占的体积百分数随着活化温度的升高而增加,而CO2则相应降低。此外,热解气中CH4的含量也会随着活化温度的上升而略有提高,说明较高的活化温度更有利于热解气的资源利用。热解油组分较为复杂,每个温度条件下的液态产物都包括上百种化合物,可分为烷烃,烯烃,苯类,酚类,腈类,杂环化合物,多环芳烃,有机酸,酰胺,酯类,甾体,醇,酮以及其他类共14大类型,其中以有机酸、腈类和甾体类有机物含量居多。随着活化温度的升高,有机酸和多环芳烃的含量有所增加,而酚类化合物的含量则有所降低;当活化温度升高至650℃以上时,甾体类有机物含量明显降低。     

初温和终温对废轮胎热解产物分布影响

以热重分析和固定床热解实验为基础,研究初温和终温对废轮胎热解产率及气相产物特性影响。实验结果表明:废轮胎的热解过程存在两个主要失重过程,第一失重温度区间为200～500℃,第二失重温度区间为650～800℃;升温速率仅改变了热解的最大失重速率,并未改变废轮胎最终热解失重率。固定床实验表明:初始温度低于100℃时,废轮胎在800℃时热解已基本结束;当终温为800℃,初始温度在100～550℃范围内时,随着初始温度的提高,固、气两相产物产率均提高,而液相产物产率降低;其中气相中H2、CO、CH4的含量高于初始温度小于100℃时的含量;分析认为:可通过调节热解的初始温度调节废轮胎热解在不同热解阶段的时间分配,适当提高热解初始温度有利于提高整个热解过程中的时间利用效率、改变废轮胎热解产物的分布;废轮胎热解气化的最佳温度区间为500～800℃。     

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.