Ca(OH)_2絮凝沉淀-臭氧氧化垃圾渗滤液生化出水提高反渗透性能

为了提高生化出水的反渗透性能,本文提出采用Ca(OH)_2絮凝沉淀预处理生化出水,再经O_3氧化后,用于反渗透膜的深度处理工艺.研究表明,Ca(OH)_2絮凝沉淀可以有效地去除垃圾渗滤液生化出水中的大分子有机物及Ca~(2+)、Mg~(2+)离子.当废水絮凝沉淀出水的电导率最低时,废水中的Ca~(2+)和Mg~(2+)离子浓度降到最低,同时也去除了较大比例的COD.对电导率最低条件下的Ca(OH)_2絮凝沉淀出水再经O_3处理后,废水中的Ca~(2+)和Mg~(2+)离子浓度和COD进一步降低,其反渗透膜通量比MBR出水的通量增高25%—35%,膜污染明显减轻,可延长膜清洗周期.臭氧氧化Ca(OH)_2絮凝沉淀出水涉及到臭氧分子直接氧化和氢氧根催化臭氧氧化两种机理,但前者起主导作用.臭氧氧化处理进一步降低了废水中的COD和Ca~(2+)、Mg~(2+)离子浓度,是提高反渗透膜通量的主要原因.     

焦化废水尾水中被O3/UV氧化的组分辨析及关键组分动力学

经过生物和化学选择性降解后残留在焦化废水尾水中的多种惰性组分,仍会对人体和水生生态系统构成重大的风险,因此将焦化废水进行深度净化是一个亟待解决的问题.以焦化废水尾水为研究对象,采用自主研制的O3/UV催化氧化流化床反应器,从焦化废水尾水成分出发,对焦化废水尾水能被O3/UV和重铬酸钾氧化的物质构成进行剖析,考察了pH、初始COD浓度对O3/UV氧化焦化废水尾水效果的影响,并对焦化废水被氧化的组分进行模拟动力学的统计性分析.实验表明,O3/UV比重铬酸钾的氧化能力更强,焦化废水尾水中能被O3/UV氧化的成分不仅包括COD,还包括对COD几乎没有贡献的NH4+-N等组分,初始pH=10—11时尾水COD氧化去除效果最佳,初始COD浓度越高,反应速率越大;O3/UV催化氧化焦化废水尾水中COD时符合一级动力学模型,而NH4+-N被O3/UV氧化反应符合零级动力学模型;由于废水中存在SCN-、CN-等含氮物质,被O3/UV氧化后使得NH4+-N浓度呈现先增后降的趋势,NH4+-N浓度达到最大值的时间与废水中含氮物质的含量呈正相关.结果表明,O3/UV催化氧化流化床反应器对焦化废水尾水具有深度处理效果,依赖于污染物组分的还原活性顺序、降解动力学的应用以及流态化的高传质效率.     

焦化废水污染指标的相关性分析

焦化废水包含不同形态与化合态的化合物.废水中各类化合物在降解过程中的变化对污染风险的判断和水处理工艺的选择都有很大的影响.以74篇国内外有关焦化废水生物处理的文献作为统计背景值,结合课题组近10年的基础研究与工程实践,分析存在于焦化废水中污染指标之间的相互依赖关系,解析COD、TN、色度的构成,评价我国目前的执行标准在指导生产方面的合理性.研究结果发现,不同企业焦化废水的水质存在较大的差异,所有焦化厂普遍忽视TP、苯、PAHs、苯并(a)芘指标的监控,COD和油类的最终出水达标率仅为16.67%和28.57%.焦化废水原水中的硫氰化物、氟离子和色度的平均浓度分别为259.37、135.66 mg·L-1和713.75倍,检出率很高,建议作为控制性指标加以关注.在目前统计到的文献中,构成焦化废水COD的组分为:挥发酚(47.28%)、硫氰化物(19.48%)、硫化物(6.81%)、氰化物(2.41%)、油类和有机胺类等(24.02%);构成TN的组分为:氨氮(48.49%)、有机氮(35.89%)、硫氰化物(12.27%)、氰化物(2.35%)、硝态氮和亚硝态氮(1%);构成色度的主要组分有带显色基团的有机物、显色离子团和硫化物等.构成COD、TN、色度等3项指标的化合物几乎涵盖了焦化废水中的所有组分.综上所述,可将焦化废水指标归纳为COD类、TN类和色度等3大类,通过归一化管理实现简化的目标.     

整流电絮凝技术对缺氧地下水中As(Ⅲ)的原位修复

地下水中砷污染的原位修复治理对人类社会的可持续发展具有重要意义.本文研发了一种新型整流电絮凝反应体系,可实现对缺氧地下水As(Ⅲ)的原位修复.实验结果表明,最优操作条件为:电流密度为4.4 m A·cm~(-2),铁棒和MMO的阳极工作时间比值(TFe-anode/TMMO-anode)为1∶2,反应周期为24 s.在最优条件下,含有500μg·L~(-1)As(Ⅲ)的模拟地下水经过30 min电絮凝处理后砷的固定脱除效率达92%,总能耗为0.11 kW·hm~(-3).此外,水体中的HCO_3~-和PO_4~(3-)等无机阴离子对砷的固定具有抑制作用.在该反应体系内,电解生成的Fe(Ⅱ)与O2之间的氧化反应生成具有强氧化性的Fe(Ⅳ)可有效将As(Ⅲ)氧化成毒性较小且更易于固定脱除的As(Ⅴ),进而显著促进了砷在Fe(Ⅲ)絮凝沉淀作用下的固定脱除.     

絮凝-光催化处理实际染料废水的研究

采用絮凝-光催化氧化工艺成功地处理了实际染料废水;研究了COD光催化降解动力学。COD和BOD5浓度分别为2169mg／L、295mg／L的染料废水,经絮凝-光催化处理后,出水COD和BOD5分别为214mg／L、18．5mg／L,去除率分别为90．1％、93．7％。向光催化体系中加入H2O2,可促进COD与BOD5的去除。该工艺可处理高浓度染料废水。     

垃圾渗滤液生化出水电化学处理技术

以垃圾渗滤液生化出水为研究对象,利用Ti/RuO_2阳极、铁网双极电极及Cu-Zn阴极组成的Ti/RuO_2-Fe-Cu/Zn电化学体系进行电化学降解研究,讨论了电流密度、氯离子浓度和初始pH值对反应的影响及双极电极的作用.研究结果表明,当电流密度为100 m A·cm-2、初始氯离子浓度为2840 mg·L-1及初始pH值为8.5时,污染物的降解效率最高,电解4 h时,CODCr、NH+4-N、TN和TOC的去除率可分别达到94.12%、99.55%、94.17%和61.65%;在Ti/RuO_2-Fe-Cu/Zn电化学体系中,铁网电极的存在不仅可以强化有机物去除,并且可以有效抑制硝酸盐的积累,提升TN的去除能力;三维荧光分析表明,电解3 h,类蛋白质类物质和类腐殖质类物质荧光强度分别降低53.41%和71.02%,有机物矿化度升高.     

电化学氧化耦合铁感应电极激发过硫酸盐氧化处理焦化废水生化出水

采用电化学氧化(EC)耦合铁(IP)感应电极激发过硫酸盐(KPS)氧化处理焦化废水生化出水,在反应器阴、阳极之间等距离嵌入铁板构建电化学双电解反应体系.该体系中,铁板作为感应电极,充当阳极材料的同时兼具有阴极材料的作用,加快过硫酸盐的活化.在电化学氧化耦合铁感应电极激发过硫酸盐(EC/IP/KPS)试验中,分别将电解时间(0—50 min)、电流密度(0—60 mA·cm~(-2))和过硫酸钾(KPS)投加量(0—5 mmol·L~(-1))作为控制条件,探讨了在不同的影响条件下该电化学反应体系对水中COD、TOC及UV_(254)等有机物污染指标的降解程度.在此基础上,利用SEM、EDS、XRD和XPS等对EC/IP/KPS过程中产生的絮凝物进行了表征,进而推断EC/IP/KPS系统的反应机理.结果表明,在EC/IP/KPS系统中的耦合作用下,当电解时间为30 min、电流密度为30 mA·cm~(-2)、过硫酸钾浓度为2 mmol·L~(-1)时,COD去除率可达77.0%、TOC去除率为54.0%,UV_(254)值明显降低.此外,还对3种不同的实验过程进行了对比,发现EC/IP/KPS系统的处理效果要明显优于KPS和EC/IP处理体系.     

零价铁还原和过硫酸盐氧化联合降解水中硝基苯

将零价铁(Fe0)的还原和过硫酸盐(persulfate,PS)的高级氧化技术结合用于水中难降解有机污染物硝基苯的去除.研究结果表明,Fe0在常温常压下可将硝基苯还原生成苯胺,随着Fe0投加量的增加,硝基苯还原为苯胺的速率逐渐增大.PS本身对硝基苯氧化作用不明显,但在Fe0与PS二者联合体系中,硝基苯和苯胺同时被去除,而且随着PS投加量的增加二者被去除的速度也随之增加.在Fe0还原和PS氧化联合处理硝基苯的体系中可能存在两个过程,一是Fe0还原硝基苯产生苯胺和二价铁离子Fe2+,二是Fe2+催化PS产生强氧化性的硫酸根自由基将苯胺氧化降解.     

BDD-Fe-NADE电芬顿系统降解磺胺类抗生素的作用机理

本研究构建了以BDD电极为阳极,自然空气扩散电极(natural air diffusion electrode,NADE)为阴极,零价铁作为催化剂的电芬顿系统,深入探索了该系统对磺胺嘧啶(sulfadiazine,SD)的降解效果和机理.相较于其他系统,BDD-Fe-NADE系统降解优势明显.为进一步探索系统的作用机理,在BDD阳极和NADE阴极之间加入质子交换膜,构建双室降解系统,分别计算阳极室和阴极室中直接电子转移(direct electron transfer,DET)、H₂O₂、·OH、S₂O₈^2-和·SO₄^-等氧化性粒子对于磺胺嘧啶降解的贡献率.结果表明,在阳极室中,电极氧化和Fe²⁺催化S₂O₈^2-产生的·SO₄^-起主要氧化作用,贡献率分别为49.02%和35.29%;在阴极室中,Fe     

多通道网状电极电化学预处理垃圾渗滤液反渗透浓缩液

反渗透(Reverse Osmosis,RO)因出水水质好、运行成本低等优势常用于垃圾渗滤液的处理,但产生的RO浓缩液具有COD高、色度高、盐分高、难降解等特点,其处理存在效果差、能耗和成本均较高等问题.本工作采用氧化钌/氧化铱涂层电极(RuO2/IrO2-Ti)的钛网为阳极,以304不锈钢电极为阴极,设计制作了6通道的电化学反应器,通过电化学氧化处理RO浓缩液,研究考查了电流密度、循环流速、比电极面积等参数对COD去除效果的影响,分析了电化学氧化去除难降解有机物并同时脱盐的过程机理与能耗.结果表明,在电流密度32.89 mA·cm^-2,循环流速0.46 cm·s^-1,比电极面积65.10 m²·m^-3的条件下,电化学氧化处理RO浓缩液3 h,COD去除率可达68.0%,TOC去除率可达40.6%,脱盐率可达72.1%,去除单位质量COD能耗仅为常规的板状电极电化学反应器的25.5%.本工作可为垃圾渗滤液RO浓缩液的预处理提供新思路.     

On the behaviour of the residence time at the bottom of the mixed layer

To understand why the findings of Deleersnijder et al. [(2006), Environ Fluid Mech 6: 25–42]—the residence time in the mixed layer in not necessarily zero at the pycnocline—are consistent with those of Delhez and Deleersnijder [(2006), Ocean Dyn 56:139–150]—the residence time in a control domain vanishes at the open boundaries of this control domain—, it is necessary to consider a control domain that includes part of the pycnocline, in which the eddy diffusivity is assumed to be zero. Then, depending on the behaviour of the eddy diffusivity near the bottom of the mixed layer, the residence time may be seen to exhibit a discontinuity at the interface between the mixed layer and the pycnocline. If such a discontinuity exists, the residence time is non-zero in the former and zero in the latter. This is illustrated by analytical solutions obtained under the assumption that the eddy diffusivity is constant in the mixed layer.     

知识型员工的特点、激励及管理对策研究

知识经济时代，企业最宝贵的财富是知识型员工。知识型员工是生产力的代表。知识型员工的工作效率决定了企业的竞争能力．因此。如何激励知识型员工成为企业探讨的一个重要问题．本文从知识型员工的特点入手。按有关知识管理专家提出的激励因素，从四个方面阐述了对知识型员工的激励策略。并提出了对知识型员工的管理对策．     

豪猪消化系统的解剖研究

为了了解豪猪的消化生理,为豪猪的人工饲养技术研究提供基础依据,以达到高效饲养豪猪的目的,笔者对豪猪的消化器官进行了系统解剖研究.结果表明:豪猪的胃为单室胃.盲肠很发达,这与其能够消化植物纤维有关.豪猪肝脏很发达,其重量为402 g,是其体重的4.59%,肝脏分叶多而明显.     

Adjusting the economy to the new energy realities of the second half of the age of oil

Our research indicates that, due to the depletion of conventional, and hence cheap, crude oil supplies (i.e. peak oil), increasing the supply of oil in the future would require exploiting lower quality resources (i.e. expensive), and thus will most likely occur only at high prices. This situation creates a system of feedbacks where economic growth, which requires more oil, would require high oil prices that will undermine that economic growth. We conclude that the economic growth of the past 40 years is unlikely to continue unless there is some remarkable change in how we manage our economy.     

Splitting the tail of the displacement kernel shows the unimportance of kurtosis

Animals disperse in space through different movement behaviors, resulting in different displacement distances. This is often described with a displacement kernel where the long-distance dispersers are within the tail of the kernel. A displacement with a large proportion of long-distance dispersers may have impact on different aspects of spatial ecology such as invasion speed, population persistence, and distribution. It is, however, unclear whether the kurtosis of the kernel plays a major role since a fatter tail also influences the variance of the kernel. We modeled displacement in landscapes with different amounts and configurations of habitats and handled kurtosis and variance separately to study how these affected population distribution and transition time. We conclude that kurtosis is not important for any of these aspects of spatial ecology. The variance of the kernel, on the other hand, was of great importance to both population distribution and transition time. We argue that separating variance and kurtosis can cast new light on the way in which long-distance dispersers are important in ecological processes. Consequences for empirical studies are discussed.     

Assessing the relation between the distribution of salt-marsh communities and the sediment budget of the North Norfolk coast

Very high resolution imagery from an airborne multi-spectrål scanner has been used to estimate the distribution of different salt-marsh communities along a 30-km stretch of the North Norfolk coast. Field observations have been used to develop a mathematical relationship between the vegetation, physical environment and sediment accumulation. This relationship has been used to produce provisional sediment accretion maps for the north Norfolk coast.     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.