185 resultados para PAHs-degrading microorganisms
Resumo:
With the continually increase both in the amount of wastewater disposal and in the treatment rate, more and more sewage sludge has been produced. An economic estimate was taken on the different sewage sludge disposal and treatment technologies, and led to the conclusion that compost is an effective way to make sewage sludge harmless, stable and resourceable. Normally, there are several ways to treat sewage sludge, such as landfill, compost, incineration and so on. These technologies will cost 300-1000 Y per ton of sludge. Among those ways, landfill is the cheapest one and operates easily, however, it just postpones the pollution instead of eventually eliminating the pollution; The amount of the sludge will reduce dramatically after incineration, while incineration will take a very high investment in the beginning, at the same time, it's very hard to maintain running; Sewage sludge will be resourceful after composting treantment, thus makes up the treatment cost, makes composting is the most economical way. Compost production is safe when correctly used, compost is a important way to treat sewage sludge. Oxygen is an important control factor in aerobic composting that has great effects on temperature and microorganisms. The gas gathering and transfering system of an online oxygen monitoring system for composting were bettermented to prolong the monitoring system's running period. The oxygen concentration changes in various aerobic composting stage were studied, and conclusions came to that oxygen concentration changes much faster in the oxygen concentration increasing stage than that in the declining stage; the better the aerobic condition is, the sooner the monitoring system starts to work. The minimal oxygen concentration during a ventilation cycle often falls at the beginning, then ascends in the composting period; at the same time, oxygen concentration changes fast in the early composting stage(temperature increasing stage), much slower in the middle stage(continouns thermophilic stage),and seldom changes in the late composting stage(temperature declining stage). With the help of the oxygen realtime-online monitoring system, oxygen concentrations was measured. During the composting period, water contents was analyzed after sampled. It's found that water contents (WC) and Oxygen concentration can both influence the composting process, and the control rule varies in the various composting stages. Essentially, the rule that water and oxygen control the composting process comes from water counterchecks the oxygen transferring to the composting substrate. The most influential factor to the WC and to the oxygen is the components in the composting pile. In the temperature increasing stage, seldom microorganisms exist in the composting pile with low activity, thus oxygen can meet with microorganisms' need, and WC is the dominant factor. In the high temperature (continouns thermophilic) stage, composting process is controlled by WC and oxygen, essentially by WC, at the same time, their influence somehow is not remarkable. In the temperature declining stage, WC and oxygen influence the composting process little. It's also found that the composting process will differ even if under the same components, thus to equably mix the components can avoid WC focusing in some place and let the composting pile to be aerobic. In one sentence, aerobic state is the most important factor in the composting process, suitable bulking material will be useful to the composting control.
Resumo:
多环芳烃(PAHs)是两个或两个以上苯环连接在一起的烃类化合物;环境中它主要来源于煤、石油、木材、有机高分子化合物、烟草和其他碳氢化合物的不完全燃烧.PAHs在环境中无处不在,且具有致癌性、致畸性、致突变性,生物累积性使它能长期滞留在环境中.因此PAHs的研究受到了环境工作者的极大关注.准确把握环境中多环芳烃的行为、主要来源及归宿,对有效控制污染、保护人类健康有非常重要的意义.
Resumo:
简述煤矿废弃物的环境地球化学效应和治理方法。分别论述了煤矸石山的自燃、淋滤和煤矿矿井水的环境效应。研究发现,煤矸石自燃会释放出SO2、CO、H2S、CO2、NOx、CH4、多环芳烃(PAHs)等多种有毒有害物质;煤矸石中的有害元素As、Cd、F、Hg、Mo、Pb等含量多与硫化物、硫酸盐等正相关,连续化学浸取能将很大部分毒害元素溶出;矿井水直接排放会引起地下水位下降和环境污染。目前我国对煤矿废弃物的环境效应研究已经很重视,但煤矸石和矿井水资源化治理还存在一些问题。
Resumo:
自然界水体(如地下水、湖泊、河流及海洋)中的天然有机质(NOM)因具有显著的生态及环境功能而受到人们的广泛关注。NOM作为全球碳循环的主要组成部分,是水体中异养型微生物生长所需碳及能量的重要来源。此外,NOM对湖泊生态系统中的多种物理、化学过程具有不同程度的影响:NOM中的有机酸对淡水体系的酸度具有控制作用而且对酸沉降有一定的缓冲作用;NOM通过减弱可见光及紫外线照射从而影响淡水系统的光化学环境,这一方面降低了水体中自养生物的繁衍速度,同时保护水生生物免受有害的紫外线辐射。更为重要的是,NOM能够影响环境中污染物的命运,比如重金属离子和疏水性有机污染物与天然有机质结合后,其迁移途径、溶解度、生物可利用性及毒性受到明显的控制,这样其对环境中生物的危害性减弱。多环芳烃(PAHs)是一类对环境危害极大的疏水性有机污染物,多数PAHs对有机体具有毒性和致癌性而被美国环保署(EPA)列为优先处理的污染物。因此,确定NOM-PAHs反应的强弱,即PAHs在NOM中的分配系数(Kdoc)以及NOM的物化特性对Kdoc的影响对于预测PAHs毒性和生物可利用性大小、了解NOM-PAHs相互作用的机理及确立污染预测模型具有十分重大的意义。前人的研究结果表明,多环芳烃与天然有机质相互作用的分配系数Kdoc的与PAHs的疏水度(即Kow大小)、NOM的物化特性(如芳香度、脂肪碳含量、分子量及极性等)和水化学参数(pH、离子强度等)有很大的相关性。然而,许多学者在NOM的物化特性对分配系数的影响方面存有较大分歧。前人在研究天然有机质与多环芳烃之间的相互作用时所用的NOM多为腐殖质,即水体NOM中的疏水性组分,而其中的亲水性组分与PAHs的结合作用文献中却鲜见提及,因此人们对其结合作用的特性如反应机理和结合作用强弱等的了解十分有限。 本论文利用XAD树脂分离技术把红枫湖水体中天然有机质分成了疏水性酸、碱、中性物质和亲水性酸、碱、中性物质等六种有机组分。同时运用元素分析、有机碳分析仪、紫外-可见分光光度,高效液相体积排阻色谱、三维荧光光谱和荧光偏振技术等现代分析方法,对各有机组分的物理、化学特性进行了表征。荧光光谱技术被用于研究水化学参数对腐殖质荧光特性和分子构型的影响以及测定Amherst腐殖酸(Amherst HA)、垃圾渗滤液富里酸(LF FA)和红枫湖NOM有机组分与多环芳烃苝、菲和蒽的结合系数(分配系数、条件稳定常数)并探讨了影响分配系数的各种因素和NOM与多环芳烃相互作用的机理。本论文的获得的主要结果如下: 1. 在水化学参数对腐殖质荧光特性及分子构型的影响方面: 在NOM与PAHs相互作用过程中,腐殖质的分子构型起着关键性的作用,而其分子构型又受到其本身的浓度、溶液的pH和离子强度等水化学参数的影响。本论文运用三维荧光光谱和荧光偏振技术研究了水化学参数对腐殖质荧光特性的影响,并由此推断其分子构型变化情况。实验结果表明随着腐殖质浓度、溶液的pH和离子强度的改变,腐殖质荧光特性(如荧光强度、荧光峰位和荧光偏振值等)出现不同程度的变化,揭示了腐殖质分子构型的改变。因此,本实验结果有利于深入了解腐殖质的分子构型及其对吸附PAHs的重要影响,对理解NOM的环境行为具有一定的理论价值。 2. 运用荧光猝灭滴定法研究Amherst HA和红枫湖NOM有机组分对多环芳烃苝、菲和蒽的吸附作用,结果表明NOM对多环芳烃的吸附能力与其中芳香结构单元有很强的相关性,logKdoc值与NOM在280 nm处的摩尔吸收(ε280)和分子量有线性度较高的正比关系,而C/H原子比值对不饱和碳含量(芳香度)并没有很好的指示作用。同时,脂肪碳(0-50 ppm)中的聚亚甲基碳对吸附PAHs也有很大的贡献,而有机组分的极性与分配系数有明显的负相关性。不同种类的多环芳烃与NOM有机组分的结合能力有很大的差异,这取决于不同PAHs的疏水度大小。本研究结果有利于弥合前人在NOM物化特性对PAHs吸附能力的影响方面的分歧,揭示了NOM的组成和结构在与PAHs等疏水性有机污染物相互作用方面的重要影响。 3. 在结合机理方面,苝与NOM有机组分结合的Stern-Volmer图具有较高的线性度,这表明其结合机理以疏水反应(或分配)为主,而菲和蒽与有机组分相互作用的吸附等温线显示较多的非线性特征表明极性反应为主要反应机理,结合过程以吸附为主。在红枫湖NOM有机组分中,疏水性组分显示对PAHs较高的结合能力,同时疏水性组分与PAHs相互作用的吸附等温线具有较高的线性度。这一结果揭示了不同种类的PAHs和各NOM有机组分之间结合机理的差异,加深了人们对NOM与PAHs相互作用机理的认识。 4. 前人在研究pH、离子强度等水化学参数对分配系数的影响方面得到的结果多有矛盾之处,同时,对实验结果的解释也不尽相同。本实验结果表明分配系数随pH增加而下降;离子强度对分配系数的影响比较复杂,就总体趋势而言,增加离子强度有利于对PAHs吸附能力的提高,这一结果初步揭示了水化学参数对PAHs分配系数的影响,丰富了人们对其影响机理的认识。 5. 运用荧光偏振技术测定了蒽与Amherst HA、LF FA和红枫湖NOM有机组分的条件稳定常数,结果如下:随着NOM浓度增加,蒽的荧光偏振值不断下降,这表明蒽的分子构型由平面线性向圆柱状转变。在所有NOM样品中,土壤源的Amherst HA与蒽结合的条件稳定常数最大(pH 4时logK=5.6,pH 6时 logK=5.4);就NOM有机组分而言,疏水性组分的logK变化范围在pH 6时为(4.4-5.2),而亲水性组分为(4.3-4.8),这表明疏水性组分具有相对较高的蒽吸附能力。实验结果有利于了解PAHs与NOM相互作用前后的分子构型变化情况,揭示了不同的NOM有机组分在吸附PAHs过程中的差异。
Resumo:
The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for environmental analysis has been mainly focused on qualitative analysis of high-mass molecules, such as toxins, humic acid, and microorganisms. Herein,we describe a novel MALDI-TOF-MS method with a matrix of oxidized carbon nanotubes for analysis of low-mass compounds in environmental samples. A number of chemicals in the environment were qualitatively analyzed by the present method, and it was found that most of them, especially the highly polar chemicals, were measurable with high sensitivity. With the intrinsic ability to measure high-mass chemicals, this method can compensate for the current shortage of methods for environmental analysis for the measurement of highly polar or high-mass chemicals. For sample analysis, arsenic speciation in Chinese traditional medicines was qualified and diphenylolpropane in water samples was quantified. With the relatively high tolerance of the method to interfering molecules, a simple pretreatment or even no pretreatment could be employed before MS detection. Furthermore, this method can be employed in a high-throughput format.