同步硝化反硝化好氧颗粒污泥的快速培养

建立2个反应器(R0、R1)培养好氧颗粒污泥,并通过向R1投加生物质炭促进颗粒污泥的形成。结果表明:投加1.5 g/L的生物质炭可加速颗粒化进程,在第11天形成以生物质炭作为晶核的颗粒污泥;与R0相比,R1中的颗粒污泥结构更致密、表面更光滑。然而生物质炭的投加对反应器性能无明显影响:2个反应器的COD和总氮去除率都可达到95%和65%以上;在一个反应周期内反应器中均无NO_3~--N和NO_2~--N积累,表明2个反应器均实现了同步硝化反硝化脱氮。     

电子受体及投加方式对反硝化除磷及N_2O释放影响

接种普通活性污泥,以乙酸钠和硝酸钾为基质,在厌氧/缺氧SBR系统中成功启动了反硝化除磷,单周期脱氮、除磷效率分别达到99.95%和72.07%,N_2O转化率(N_2O释放量/去除的TN量)为16.41%。在此基础上,以厌氧末污泥为对象通过批式实验对比研究了NO_2~--N及其投加方式对反硝化除磷及N_2O释放的影响,结果表明,一次性投加NO_2~--N时,脱氮、除磷效率分别下降至55.44%和33.54%,N_2O转化率达到25.08%;当改变亚硝氮的投加次数分别为4、3、2次时,N_2O转化率分别为27.05%、23.93%和27.25%,除磷效率分别达到81.82%、80.70%和56.56%。结果表明,分多次进水并控制较低的NO_2~--N浓度,可大幅提高反硝化除磷效率,而且不会导致N_2O转化率增大。     

添加零价铁的反硝化系统中发生的主要反应

分别采用零价铁、反硝化污泥及零价铁+反硝化污泥的系统处理含NO_3~--N的废水,探讨零价铁的添加对反硝化系统脱氮效果的影响及系统中发生的主要反应。结果表明,零价铁系统对废水中的NO_3~--N无去除效果;当零价铁+反硝化污泥系统对废水中NO_3~--N的去除率达到100%时,反硝化污泥系统对废水中的NO_3~--N去除率仅为60.1%。零价铁+反硝化污泥系统中主要发生零价铁参与的氧化还原反应及微生物参与的生物反硝化反应。     

聚糖菌反硝化影响因素及内碳源转化特性

在SBR反应器中以乙酸钠为碳源、NO_3~--N为电子受体成功富集了反硝化聚糖菌,并采用批次实验进一步考察了进水C/N比(3.3,6.7,10)、电子受体(NO_3~--N、NO_2~--N)、碳源类型(乙酸钠、葡萄糖)对反硝化聚糖菌活性的影响及内碳源转化特性。实验结果表明,进水C/N比越高,系统NO_x~--N去除率越高,厌氧段合成PHB越多,但进水C/N比过高会导致普通反硝化菌占优势,影响内碳源反硝化效率,进水C/N比为6.7较为合适;以NO_3~--N为电子受体长期培养的DGAOs系统未经NO_2~--N驯化,对NO_2~--N同样具有良好的反硝化性能,在投加与NO_3~--N相同浓度的NO_2~--N后,系统NO_x~--N去除率达89.6%;当以葡萄糖为碳源时,DPAOs在厌氧段合成的PHB的量仅为以乙酸钠为碳源时合成PHB量的79.5%,且厌氧段葡萄糖利用率仅为72.8%,远远小于乙酸钠的利用率。     

微气泡曝气生物膜反应器低C/N废水脱氮探究

针对低C/N废水脱氮效率低的现状,建立了微曝气生物膜反应器,分析了启动期微气泡曝气生物膜反应器污染物去除特征,探究了温度对微气泡曝气生物膜反应器脱氮效率的影响并揭示相关机制。结果表明,反应器启动稳定后COD、NH_4~+-N和TN的去除率分别提高至92.3%、92.5%和71.5%。温度能影响生物脱氮效率,且35℃时COD去除率最高,可高达92.3%～93.4%。温度同时影响硝化及反硝化过程,且温度升高有利于促进NO_2~--N的积累与NO_3~--N的反硝化。温度升高降低了反应器内污泥胞外聚合物的含量。当温度为35℃时,脱氮过程关键酶活性显著高于15℃;温度升高利于硝化及反硝化过程关键微生物的丰度。     

Fe~(3+)对好氧颗粒污泥形成的影响及硝化特性研究

在3只序批式间歇反应器(SBR)进水中分别添加质量浓度为1、10、0 mg/L的Fe~(3+),形成R1、R2和R3,研究Fe~(3+)对颗粒污泥形成的影响,并对其硝化动力学特性进行分析。结果表明,3个反应器皆能在较短时间内培养出好氧颗粒污泥,Fe~(3+)对污泥颗粒化进程无明显促进作用,但对污泥颗粒形貌影响较大;低含量Fe~(3+)(质量浓度1 mg/L)会显著提高好氧颗粒污泥的COD去除率与NH4+-N转化能力,Fe~(3+)可促进好氧颗粒污泥的硝化过程;采用Monod模型对硝化动力学过程进行拟合,最大比去除速率v_(m1)v_(m2)v_(m3),进一步表明低含量Fe~(3+)更易实现高效的硝化过程。高通量测序结果则证实Fe~(3+)的投加可提升好氧颗粒污泥的脱氮除碳性能。     

葡萄糖碳源反硝化脱氮过程亚硝酸盐积累特征探究

为了探究葡萄糖作为补充碳源对反硝化规律的影响,建立序批式反应器(SBR),考察了不同乙酸与葡萄糖混合比对氨氮氧化及亚硝酸盐积累的影响。结果表明乙酸与葡萄糖混合比及污泥负荷均能影响反硝化规律。当碳源充足时,碳源类型对硝化过程影响不显著,而对反硝化过程具有显著影响。当ρ(乙酸)/ρ(葡萄糖)为2/1时,反硝化速率快,且ρ(NO_2~--N)的最大积累量为2.24 mg/L。在污泥负荷为1 000 mg/L时,各反应器中硝态氮均能被反硝化,但ρ(乙酸)/ρ(葡萄糖)为1/2组别中反硝化速率最慢,ρ(NO_2~--N)积累量最小。NO_3~--N的存在对NO_2~-N的还原具有一定抑制作用。     

碳源对低氧多级AO工艺脱氮性能及N_2O释放的影响

以乙酸钠和丙酸钠为外加碳源,考察了碳源种类和碳氮比对多级AO工艺(分别为反应器SBR-A和SBR-P)脱氮性能及其N_2O释放的影响。结果表明,在进水COD为200 mg/L时,SBR-A和SBR-P氮去除率分别为66.7%和67.1%,磷去除率分别为51.1%和28.9%。硝化过程中,SBR-A中NH4+-N氧化速度和NO_3~--N生成速度都比SBR-P高,SBR-A中NO_2~--N和N_2O积累速度比SBR-P低。2组反应器硝化过程中N_2O释放因子均小于0.23%。在反硝化过程中,SBR-A的反硝化速度高于SBR-P,N_2O释放因子均较低;存在同时释磷时,对SBR-A的反硝化速度影响较小,而对SBR-P反硝化活性影响较大,后者反硝化速度明显低于无释磷条件下的反硝化速度;菌群均以变形菌门和拟杆菌门为主,且以陶厄氏菌属、脱氯单胞菌属、蛭弧菌属和硝化螺菌属等为主要功能菌。     

基于铁碳内电解的物化—生物耦合深度脱氮

以自制复合铁碳填料为载体,建立物化-生物耦合脱氮体系,考察了HRT、DO含量、进水pH对低C/N(COD/ρ(TN)=1.5:1)污水脱氮的影响,并通定量了物化作用对脱氮的贡献率。结果表明,在耦合体系中,NH_4~+-N通过氨氧化菌和硝化菌的作用生成NO_3~--N和NO_2~--N,NO_3~--N和NO_2~--N进入生物膜内部,自养反硝化菌以载体原电池反应所产生的[Fe~(2+)]、[H]为电子供体实现反硝化脱氮,其适宜运行条件为:HRT为4.0 h,DO的质量浓度(2.0±0.1)mg/L,进水pH为7.0±0.1,此时污水COD、NH_4~+-N、NO_3~--N、TN去除率分别可达94.6%~97.3%、82.1%~83.6%、92.1%~94.7%、89.3%~92.5%。适宜的HRT低于其它同步硝化反硝化脱氮过程。反应器内反硝化所需电子37.9%由载体物化反应供给,消除了传统生物脱氮过程对有机碳源的依赖,源缩短了脱氮所需停留时间。故该耦合体系可实现低C/N污水的高效深度脱氮。     

Cu~(2+)和Fe~(3+)对同步硝化反硝化过程N_2O释放特征的影响

针对废水中金属离子Cu~(2+)和Fe~(3+)对同步硝化反硝化(SND)污水处理过程污染物去除及温室气体氧化亚氮(N_2O)释放特征的影响进行了研究,并分析了其影响机理。结果表明,适宜浓度下Cu~(2+)和Fe~(3+)均能够强化SND过程脱氮效率;然而,长期Fe~(3+)的投加抑制了反应器中聚磷菌的生长和活性,从而使系统中总磷去除率下降2.3%～11.7%; Cu~(2+)的投加强化了亚硝酸盐还原酶和N_2O还原酶(N_2OR)的活性,从而降低了N_2O的累积和释放;而Fe~(3+)的投加刺激了SND反应器中N_2O的产生,Fe~(3+)强化了一氧化氮还原酶(NOR)的活性,使得NOR/N_2OR活性比值上升,导致N_2O的积累;同时Fe~(3+)的投加降低了SND过程厌氧阶段聚羟基脂肪酸酯的合成,导致系统中聚糖菌在与聚磷菌的竞争中占据优势,并促进了N_2O的产生;高浓度的Cu~(2+)和Fe~(3+)抑制了系统中微生物活性,从而导致脱氮除磷效率下降及N_2O积累。     

PPH治疗混合痔的护理体会

目的探讨混合痔行PPH的护理方法。方法99例混合痔患者均行PPH,手术前向患者介绍住院环境、住院须知,告知治疗方法及护理上需要的配合,饮食、排便的注意事项,术前准备等;术后体位及恢复饮食时间,大小便情况观察及各种外用药的使用,出血护理及伤口护理,肛门功能锻炼;制定入院评估,印制出院指导。结果99例患者痔核明显回缩,顺利出院。结论混合痔PPH的术前术后护理对患者顺利康复有重要意义。     

Crosslinking of styrene-butadiene rubber with polyurethanes bicapped with benzyocyclobutene

Summary A polyurethane prepared from 1,9-nonanediol and toluene-2,4-diisocyanate with M_n=11,840, was capped on both ends in a reaction with 4-(benzocyclobutenyl) methanol. The polyurethane was used to crosslink styrene-butadiene rubber through Diels-Alder reactions on the benzocyclobutene functionality. The synthesis and characterization of 4-(benzocyclobutenyl) methanol, a molecule not reported previously, is presented. The crosslinking reaction was carried out on intimate mixtures of the telechelic polyurethane and SBR at elevated temperature and pressure. Various physical properties of the crosslinked material were studied.Work done at the Department of Chemistry, University of Akron, Akron, OH 44325, USA     

Copolymerization of acrylonitrile with maleamic acid derivatives and with carboxyphenylmaleimide

Acrylonitrile was copolymerized with two N-arylmaleamic acids and with N-3-carboxyphenylmaleimide in dimethylformamide (DMF) using azobisisobutyronitrile as initiator. The reactivity ratios and the Q-e parameters of these monomers were estimated, and the resulting copolymers were characterized by viscosity measurements and thermal analysis. Thermogravimetry and differential thermal analysis data showed an improvement in the thermal behaviour of the investigated copolymers compared with that of poly(acrylonitrile). Mechanisms illustrating the role of both the acidic group and the maleimide ring in the nitrile oligomerization were proposed. The produced copolymers showed an excellent affinity towards basic dyes and better color fastness towards UV light.     

Dehydrochlorination of propylene chlorohydrin with sodium hydroxide and with catholyte

Dehydrochlorination of an aqueous solution of propylene chlorohydrin with sodium hydroxide (12·5 and 30% by weight), with catholyte (5 or 10% by weight NaOH + 14% by weight NaCl) and with milk of lime (15% by weight) were compared. The use of catholyte (10% by weight NaOH + 14% by weight NaCl) enables propylene oxide to be obtained in a yield of 94·3%, with 100% conversion of chlorohydrin. The concentration of 1,2-propylene glycol in the waste is 0·07% by weight.     

Reaction of CH-acidic compounds with thiacumulenes and alkylation with dihaloalkanes

Dithiocarboxylation of CH-acidic compounds 1 and stepwise alkylation of primarily formed dithiolates 2 yielded ketene dithioacetals 5a,b or methylenebis(dithiocarbonates) 12a–c. Reaction of 5a,b with nucleophiles afforded thiophene 7 and dithioacetals 8, 9a,b, 11, respectively. 1,3-Thiazetidines 14a,c,e and thiazolidines 14b,d,f were prepared by thiocarbamoylation of 1b,c,e and subsequent alkylation with dihaloalkanes.     

复合扰流柱的螺旋内构件反应器内流体的宏观混合

在管式反应器内插入复合扰流柱的螺旋型内构件,采用脉冲示踪法测定了反应器内流体的停留时间分布,研究了器内流体的宏观混合特性,分析了该内构件强化混合的机理. 结果表明,复合扰流柱的螺旋型内构件反应器内的流体流动更接近于活塞流,其轴向扩散模型参数Pe为螺旋型内构件反应器的1.02~1.28倍,为不带内构件反应器的1.35~1.77倍. 复合扰流柱的螺旋型内构件能显著增强器内的二次流动,从而强化了宏观混合效果.     

Syntheses of bismaleimides with ester units and their polymerization with diamines

Five structurally different bismaleimides were synthesized by reaction between 3(4)‐maleimidobenzylchloride with various diphenols. They were characterized by infrared (IR) and proton nuclear magnetic resonance (¹H‐NMR) spectroscopy. Thermal characterization of monomers and their polymers was accomplished by differential scanning calorimetry (DSC) and dynamic thermogravimetric analysis (TGA). Polyaminobismaleimides having inherent viscosities of 0.1–0.4 dL/g were prepared by Michael addition of diamines to bismaleimides. The polymers are soluble in solvents as DMF, NMP, and DMSO, and afforded film from their solutions. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 750–757, 2002; DOI 10.1002/app.10294     

AN-VA-MAS体系与AN-VA体系两种腈纶生产情况的对比

通过对聚合物和纤维的主要质量指标以及聚合釜生产能力变化的对比分析,说明了在腈纶生产中,使用AN-VA-MAS三元体系的聚合工艺优于AN-VA的二元体系聚合工艺.     

单双切向环流式旋风除尘器的比较

以粉煤灰 空气为实验物系 ,测定了单、双切向环流式旋风除尘器的除尘效率和压降。实验结果表明 ,双切向环流式旋风除尘器的除尘效率比单切向环流式旋风除尘器的除尘效率有所提高 ,压降比单切向环流式旋风除尘器的压降低 2 0 0Pa ,处理量有所增大