Biofouling in Membrane Bioreactor

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Biofouling in Membrane Bioreactor A. Ramesh a ; D. J. Lee a ; M. L. Wang b ; J. P. Hsu a ; R. S. Juang c ; K. J. Hwang d ; J. C. Liu e ; S. J. Tseng f

a Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan

b Department of

Environmental Engineering, Hung Kuang University, Taichung, Taiwan c Department of Chemical

Engineering and Materials Science, Yuan Ze University, Taoyuan, Taiwan d Department of Chemical

and Materials Engineering, Tamkang University, Taipei County, Tamsui, Taiwan e Department of

Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan f Department of Mathematics, Tamkang University, Tamsui, Taipei County, Taiwan

To cite this Article Ramesh, A. , Lee, D. J. , Wang, M. L. , Hsu, J. P. , Juang, R. S. , Hwang, K. J. , Liu, J. C. and Tseng, S.J.(2006) 'Biofouling in Membrane Bioreactor', Separation Science and Technology, 41: 7, 1345 — 1370

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Biofouling in Membrane Bioreactor

A.Ramesh and D.J.Lee

Department of Chemical Engineering,National Taiwan University,

Taipei,Taiwan

M.L.Wang

Department of Environmental Engineering,Hung Kuang University,

Taichung,Taiwan

J.P.Hsu

Department of Chemical Engineering,National Taiwan University,

Taipei,Taiwan

R.S.Juang

Department of Chemical Engineering and Materials Science,

Yuan Ze University,Taoyuan,Taiwan

K.J.Hwang

Department of Chemical and Materials Engineering,Tamkang

University,Tamsui,Taipei County,Taiwan

J.C.Liu

Department of Chemical Engineering,National Taiwan University

of Science and Technology,Taipei,Taiwan

S.J.Tseng

Department of Mathematics,Tamkang University,Tamsui,

Taipei County,Taiwan

Received 10November 2005,Accepted 10February 2006

Address correspondence to D.J.Lee,Department of Chemical Engineering,National Taiwan University,Taipei 106,Taiwan.Tel.:t886-2-2362-5632;E-mail:djlee@https://www.sodocs.net/doc/1510198053.html,.tw

Separation Science and Technology ,41:1345–1370,2006

Copyright #Taylor &Francis Group,LLC

ISSN 0149-6395print /1520-5754online

DOI:

10.1080/01496390600633782

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Abstract:A membrane bioreactor (MBR)combines membrane separation and biological treatment,normally involving the activated sludge process,in municipal wastewater treatment.Despite excellent performance over years of full-scale operation,the interactions between microbes and the membrane in the MBR process,which determine its design and operational criteria,remain unclear.This report reviewed research regarding how numerous process parameters impact biofouling rates and,in particular,the possible contribution of microbial products to biofouling.This study also characterized different fractions of microbial products and assessed their potential affect on membrane fouling.

Keywords:MBR,fouling,mechanisms,extracellular polymeric substances INTRODUCTION

The activated sludge process is used to treat municipal and industrial waste-waters.Micro-organisms in aerated mixed liquor degrade organic pollutants such as organic carbon and nitrogen compounds.However,the activated sludge process requires large tanks for aeration and sedimentation,produces a vast excess of sludge that must be disposed of,and experiences frequent technical dif?culties,such as bulking and foaming.Furthermore,the potential of the activated sludge process to degrade organic matter is limited.The hygienic qualities of the treated water have attracted increasing concern,because of the strong correlation between the use of the surface water and the prevalence of infections of the body.

Smith et al.(1)?rst reported on the combined use of membranes in bio-logical wastewater treatment.Their idea was to directly ?lter the mixed liquor in a biological reactor,to produce quality ef?uent by totally rejecting the impurities,using a membrane.In a submerged module,the membrane is directly merged in the aerated bioreactor,with aerated bubbles sweeping over the surface of the membrane to enhance permeate ?ux and reduce fouling.The submerged MBR could be easily retro?t using an activated sludge process with minor modi?cations.Presently,hundreds of full-scale MBRs are installed annually (2).

The main advantage of using MBR technology over using other conven-tional biological processes is to produce quality water from municipal waste-water for reuse,meeting the need for saving water,particularly in regions of water shortage.Other advantages include the need for less space,lower energy consumption,and the smaller excess of sludge to be handled.All shortcom-ings of membrane systems persist in MBR applications,such as high installa-tion costs,low permeate ?ux,and occurrence of membrane degrading and fouling (3,4).Despite performing excellently over years of full-scale operation,the interactions between microbes and the membrane in the MBR process,which determine its design and operational criteria,remain unclear.Just recently some mathematical modeling works were available for MBR applications (5,6). A.Ramesh et al.1346D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

This report reviewed brie?y how numerous process parameters in?uence biofouling rates and,in particular,the possible contribution of microbial products to biofouling.

MBR PRACTICE

Micro?ltration (MF)and ultrat?ltration (UF)membranes are frequently employed in membrane bioreactor (MBR)applications.Micro?ltration membranes,which typically have pores 0.1–10m m in size,can be utilized to separate particles.The most widely used materials in micro?ltration membranes are polytetra?uoroethylene (PTFE),polypropylene (PP),poly (vinylidine ?uoride)(PVDF),polyethylene,cellulose esters,polycarbonate,polyamide,and polyetherketone.UF membranes have pores (5–100nm)and can remove macromolecules.Polyacrylonitrile,cellulose acetate,aliphatic polyamide,poly (vinylidine ?uoride),poly imide /poly (ether imide)are typically used for UF membranes.For example,Zenon,Canada,had over 150full-scale units installed by 2000and utilized submerged hollow ?ber polyethersulfone UF membranes.Other commonly employed membranes are ceramic or metallic membranes from Kubota (Japan),organic membranes made of polyvinilydene ?uoride,and polysulfone.At a vacuum pressure as high as 0.7bar,submerged UF or MF membranes typically have a constant permeate ?ux of 0.1–1m d 21.Field experience has demonstrated that side-stream type MBR require cleaning after 2months of use and submerged hollow ?ber membrane type MBR must be cleaned after 6–8months’of use,utilizing a chemical solution.

The two most critical process parameters in activated sludge processes are sludge retention time (SRT),which determines microorganism growth rate,and the hydraulic retention time (HRT),which governs pollutant removal rate.Both nutrient supply and available contact time affect bacterial growth rate;these two parameters are inter-related.In MBR,HRT,and SRT are entirely separated,enabling sludge age to be manipulated.The SRT for the MBR process is by de?nition in?nitely long and rejects solids.The energy supplied is either fully utilized by microbes for maintenance,or is transferred to higher life forms like metazoa.Consequently,the biomass concentration in the MBR process can be sustained at 10,000–60,000mg l 21,substantially higher than that in a traditional activated sludge process (3,000–4,000mg l 21).This high biomass concentration effects organic degradation (7),generating an ef?uent chemical oxygen demand (COD)of ,5mg l 21,.80%nitrogen removal (8),and ,0.5mg l 21total phosphate.The membrane rejects most ?ltrate particles.Total suspended solids (TSS)in ef?uent produced by the MBR process can easily be less than 1mg l 21,and the total coliform count can be reduced from up to 107to 100–300CPU l 21.Madaeni et al.(9)determined that membranes can completely removing viruses via UF or substantially remove viruses via MF membranes.Biofouling in Membrane Bioreactor 1347

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Particle rejection by a membrane is primarily a product of pore size (10)and the dynamic membrane situated above the pores.Wakeman (11)noted that the impact of fouling in MF and UF is associated with a matrix of feed stream,membrane and operational parameters.Among all parameters the most important are particle size distribution of the feed and membrane pore size.Cho et al.(12)indicated that rejection of natural organic matter (NOM),based on dissolved organic carbon (DOC),is controlled by the particle size excluded,electrostatic repulsion and aromaticity /hydrophobicity interaction between the membrane surface and pores.Bacteriophage at 25–65nm was effectively rejected by the UF membrane as demonstrated by Oe et al.(13),Bottino et al.(15)investigated the retention capacities of particles,microorganisms,algal,and disinfection-by products (DBPs)by MF ceramic membranes.Their experimental results showed that suspended solids and microorganisms are completely removed,whereas algal removal (99%)is near complete and TOC and chloroform retention was 64%and 56%,respectively.

Some constraints must be assessed prior to steady-state MBR operations with total sludge rejection.Zero net biomass production is required to prevent sludge accumulation in the bioreactor.Additionally,counterbalance of opposing factors controlling membrane fouling is essential guarantee a stable permeate ?ux over long-term operation.The microbial community must degrade organic matter mainly through the cell maintenance pathways;or an ecosystem must be generated in the bioreactor to achieve population equilibrium.Witzig et al.(15)assessed changes to the microbiological community utilizing MBR for complete biomass rejection.The number of ?la-mentous bacteria increases from test start to a dramatically high value during steady-state operations.Thus,the microbial community in MBR evolves to an adaptive state,fully utilizing the limited energy supply for survival.Luxmy et al.(16)noted a metazoa population,primarily composed of roti?ers and oli-gochaete worms,increases in density as the loading rate increases.These microbes are concentrated on the membrane surface and,thus,can help removing the formed cake from the surface of the membrane.

Although the detailed mechanisms and interaction among numerous process parameters were not comprehensively explored (17),new develop-ments in MBR applications are ongoing.For example,a nano?ltration membrane used in MBR applications is attracting increasing interest,partly due to frequent outbreaks of water-borne diseases in Japan and the United States,where treated municipal wastewater has been utilized as raw water.The nano?ltration membrane can ?lter out most viruses from treated water.However,since pore size of NF is substantially smaller than MF /UF membranes,fouling mechanisms change away from pore blocking to gel layer formation.The gel layer is not easily removed via backwashing as is the cake layer formed by biological cells.Moreover,modifying existing processes,such as utilizing an anoxic /aerobic membrane bioreactor,can effectively remove nitrogen and carbon simultaneously from wastewater A.Ramesh et al.

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(18).The membrane bioreactor coupling with a photocatalyst process attains suf?cient pollutant removal (19).New functional membranes,such as the ion-exchange membrane (20)or enzyme-immobilized bilayer membranes (21),have been effectively employed in MBR.

A signi?cant obstacle preventing widespread application of membrane ?ltration in wastewater treatment is the ?ux decline over time (22–24).Regardless of the complexity of an MBR system,no appropriate processes can be applied without suf?cient fouling control.The following sections discuss how various process parameters,particularly the characteristics and amount of microbial products,impact biofouling on membranes in MBR applications.

MEMBRANE FOULING

Membrane fouling is used to describe pore plugging and external pore blocking caused by deposition of particles and colloids on a membrane surface and precipitation of ?ne ]dissolved materials in membrane pores and on a membrane surface (25–28).Typically,membrane fouling results in ?ux decline and fouling increases pressure drop across the membrane.Recent examinations of membrane fouling are available in Baker and Dudley (29),Judd (30,31),Marrot et al.(32),and Liao et al.(33).

Factors controlling membrane fouling are as follows (34):

1.membrane and module (35,36);

2.operating conditions (37–41);and,

3.biomass (35,42–44),including suspended solids (45)and extracellular

polymeric substances (EPSs)(46).

The extracellular polymeric substances are a principal foulant in MBR (42,44,47–50).Leslie et al.(51)and Hodgson et al.(52)implicated EPS fouling as the cause of ?ux decline of MF membrane systems.Wisniewski and Grasmick (53)argued that solutes are a signi?cant pollutant of MBR membranes.Defrance et al.(54)noted that suspended solids are a primary foulant of MBR membranes.Bouhabila et al.(55)concluded that the colloids are the principal membrane foulant.Apparently no conclusive comments could be made based on these literature works.

Fouling-Membrane and Module

Several studies demonstrated that the ?ux decline is lower for hydrophilic membranes than hydrophobic membranes.Nakatsuka et al.(56)demonstrated that ?ux for hydrophilic membranes is quickly recovered by back washing,indicating that the substances in raw water are only minimally adsorbed by Biofouling in Membrane Bioreactor 1349

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the hydrophilic membranes.Fan et al.(57)pointed out that the ?ux decline for a hydrophobic PVDF membrane is considerably quicker than that for its hydrophilic counterpart,suggesting that particle deposition signi?cantly impacts membrane fouling.Carroll et al.(58)modi?ed the surface of an MF membrane to minimize the declining ?ux problem.Hacck et al.(59)modi?ed the hydrophobic membrane surface by grafting on a hydrophilic layer.These authors suggested that a PP membrane modi?ed by polyacrylic acid has a lower rate of ?ux decline than an unmodi?ed membrane.Other studies also utilized surface modi?cation to reduce potential of membrane fouling (60,61).Mueller and Davis (62)noted that when ?ltering a bovine serum albumin (BSA)suspension,rapid formation of a proteinous dynamic layer on a membrane surface moderates ?ltration ?ux,hence masking the effects of membrane substrate characteristics.

Membrane charge affects a membrane’s selectivity for charged particles and ions and its resistance to fouling (63).Jarusutthirak and Amy (64)noted that the membrane surface charge was correlated with fouling mechanisms.Membrane zeta potential has been shown to be effective in detecting minimal reductions in membrane ?ux (65–67).Knoell et al.(68)and Campbell et al.(69)employed quantitative structure-activity relationship (QSAR)analysis to determine the correlation between a membrane’s fouling potential and its features.

Sridang et al.(70)analyzed the fouling potential of a membrane utilizing different module con?gurations and hydrodynamic environments.Module con?guration affects membrane fouling potential markedly (71,72).Adding turbulence to membrane systems promotes ef?uent ?ux levels (73–77).Packing density of hollow ?ber modules in?uences ?ux decline and fouling rates (78,79).Yeo and Fane (80)pointed out that the hydrodynamic environ-ment for individual ?bers can differ signi?cantly depending on their position in the bundle.Scridang et al.(70)compared the fouling rates from immersed membrane systems with different bundle con?gurations.

Fouling-operating Conditions

Hydrodynamic,chemical,and biological factors moderate membrane fouling.Reversible membrane clogging is preferable to operational sake as standard cleaning can easily wash the clogging layer away.Membrane fouling resulting from the dynamic layer on a membrane’s surface decreases permeate ?ux after the operation starts.However,with adequate aeration,this ?ux decline does not normally proceed following a particular period of operation,since the fouled layer attains a dynamic balance between deposited and suspended particles (81).Chang and Judd (77)compared the fouling potentials of membranes sparged with different modes.

The critical ?ux concept presented by Field et al.(82)proposed that neg-ligible cake deposition on membrane surface exists below ?ltrate ?ux.Critical A.Ramesh et al.1350D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

?ux increases as cross?ow velocity and suspended particle size increases (83,84).Wicaksana et al.(85)demonstrated that bubbling-induced vibration of hollow ?bers increases critical ?ux.Moreover,Chang et al.

(86)indicated that fouling always occurs,even at sub-critical ?ow conditions.Such type of biofouling is noted inevitable in MBR applications (87).

Jiang et al.(88)determined that the fouling rate would be higher at low temperatures (13–148C)than at high temperatures (17–188C),probably owing to the change in ef?uent viscosity.

Fouling-Biomass

Magara and Ito (89)and Nanem and Sanderson (90)noted that a high suspended solid concentration increases membrane fouling;whereas Lee et al.(91)noted that a high amount of suspended solids on the contrary reduces membrane fouling.Lee et al.(44)argued that the EPSs should be considered as part of the suspended solid concentration when evaluating membrane fouling.Rosen-berget et al.(92)noted,based on literature ?ndings,that with an increasing mixed liquor suspended solids (MLSS)the fouling potential would be reduced when MLSS ,6,000mg l 21,and increased when MLSS .15,000mg l 21,and remained unchanged with an intermediate MLSS.Other parameters addres-sing the solid fraction on MBR fouling are effect of particle size,(40)?oc surface hydrophobicity,(93)and sludge viscosity (49,94).

Brinck et al.(95)showed that the undissocated fatty acid,predominantly presented in reduced pH,fouled the membrane more seriously than the disso-ciated species presented under alkaline conditions.Seo et al.(96)determined that the hydrophobic fraction of organic compounds fouled the membrane more than did hydrophilic fraction.Jarusutthirak et al.(97)indicate that poly-saccharide colloids accounted for most fouling of UF and NF membranes.Cho et al.(98)argued that polysaccharides and related substances are the principal foulants of UF and NF membranes.Rosenberger et al.(92)indicated the impact of soluble or colloidal fractions in organic substances,particularly polysaccharides,on membrane fouling,and thereby arguing for characterizing liquid-phase compositions when monitoring membrane process performance.

Williams and Wakeman (99)indicated that BSA fouling of MF membranes starts with protein aggregates depositing on the membrane surface,thereby blocking some pores.They indicated that protein fouling comprises of two steps:

protein adsorption and desorption on pore walls and mouths;and,

accumulation of cake on the membrane surface resulting from aggregate deposition and growth.

In a pilot-scale MBR,Kimura et al.(41)demonstrated that the food-microorganism (F /M)ratio and membrane ?ltration ?ux markedly affected Biofouling in Membrane Bioreactor 1351D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

fouling rates.Protein at high F /M ratio and carbohydrates at low F /M ratio are the principal foulants.

You et al.(100),who investigated the anaerobic membrane process,determined that both membrane fouling and scaling are most important processes hindering factors (101–103).

Based on these process parameters that effect biofouling,the following techniques have been applied to reduce fouling potential:

1.intermittent suction (104);

2.backwashing;

3.improving module con?gurations (85,105);and,

4.aeration improvement (106).

Membrane Cleaning

Physical,chemical,and biological schemes are utilized to regenerate fouled membranes.The cleaning method and cleaning frequency depend on foulant type and a membrane’s resistance to chemical cleaning agents.Choice of membrane materials,however,depends on feed composition and precipitated layers on a membrane surface and,in most cases,membranes are chosen through trial and error.

During physical cleaning,back?ushing is frequently applied to a membrane’s permeate side,forcing the solution through the membrane feed side.This technique is more effective for ceramic membrane ?ltration than for polymeric membranes,since ceramic membranes can withstand the high pressure associated with back ?ushing.Visvanathan et al.(107)and Chang and Judd (77)utilized air back?ushing to decrease cake compression and pore clogging in MBRs.Zips et al.(108)utilized both ozone and ultrasound to clean a modi?ed polysulfone membrane fouled by Pseudomonas diminuta .Lim and Bai (109)determined that sonication cleaning effectively removes loosened material still attached to a membrane surface or trapped in membrane pores.

Many chemical cleaning agents have been employed,such as nitric acid,hydrochloric acid,phosphoric acid,alkaline,carbonates,phosphates,EDTA,sodium hypochlorite,etc.Increasing temperature typically enhances cleaning ef?ciency;however,high temperatures cannot be used when cleaning most organic membranes.According to Bartlett et al.(110),particu-lar cleaning agent concentration and temperature exists for optimal cleaning.In an investigation of cleaning BSA-fouled polysulfone and HEKLA membranes,sodium hydroxide achieved suf?cient results at high temperatures (111).Based on the study by Mohammadi et al.(112)a combination of cleaning agents,such as sodium hydroxide and sodium hypochlorite,and sodium hydroxide and sodium dodecyl sulphate,clean more ef?ciently than single-agent methods.The presence of chloride ions can signi?cantly A.Ramesh et al.1352D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

decrease cleaning ef?ciency,whereas nitrate and sulphate ions improve cleaning ef?ciency.

Mild and environmentally friendly cleaning agents,such as puri?ed enzymes and surfactants,have been employed to extract biologically derived foulants from polymer membranes.Enzymes are model cleaning agents as they are speci?c for the reactions they catalyze and the substrates with which they interact.Maartens et al.(113)investigated the capability of each cleaning agent to eliminate adsorbed proteins and lipids,as well as the ability of a cleaning agent to restore the water-contact angle and pure water ?ux of the fouled membrane.Munoz-Aguado et al.(114)achieved adequate cleaning effectiveness with an enzymatic cleaning agent.Arguello et al.(115)obtained very high (90%)cleaning ef?ciencies over short period (20min)utilizing enzymatic cleaning for inorganic UF membranes fouled by whey proteins.A similar ?nding obtained by Arguello et al.(116)achieved 100%cleaning ef?ciency for protein from inorganic membranes.Allie et al.(117)demonstrated the feasibility of using of both proteases and lipages to clean their UF membranes fouled by abattoir ef?uent.

FOULING WITH MICROBIAL PRODUCTS

Microbial Products in Activated Sludge

Sludge liquor consists of living cells and microbial products,including EPSs,inert biomasses,and soluble microbial products (SMPs)(118).The EPSs are microbial products located on or outside cell surfaces that aggregate cells into ?ocs or granules,provide resistance to surrounding toxins,accumulate enzymes for cell use,and facilitate cell-cell communication (119).Early studies identi?ed polysaccharide as the most abundant component found in EPSs (120).In examining bio?lm systems,Nielsen et al.(121)noted that protein is the most abundant component of EPSs.In EPS-activated sludge,Dignac et al.(122)determined that protein is the predominant constituent.Protein has a high proportion of negatively charged amino acids and,hence,is more involved than sugars in generating electrostatic bonds with multi-valent cations,a principal factor in stabilizing aggregate structures.Addition-ally,protein is the predominant component in enzyme-based biochemical reactions.

Choi et al.(98)proposed that EPSs bind with sludge ?ocs contributed signi?cantly to permeate ?ux decline,resulting from the altered cake charac-teristics produced by the presence of EPSs.The same authors demonstrated that organic substances in supernatant do not contribute substantially to membrane fouling,a ?nding consistent with the conclusion obtained by Lee et al.(45)and Defrance et al.(55)The fraction of non-settled organic sub-stances increases membrane fouling (123–125)via adsorption of macromol-ecular substances on a membrane and progressive pore clogging (45,126).Biofouling in Membrane Bioreactor 1353D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

The EPSs were further differentiated into extractable EPSs,the EPS fraction bound tightly with solid surfaces,and soluble EPSs (also called slime polymers),the fraction able to move freely between sludge ?ocs and sur-rounding liquor (8).Other classi?cation paradigms have separated EPSs into “loosely bound”and “tightly bound”fractions (127).Leung (128)determined that most extraction approaches described in literature effectively extract both loosely and tightly bound EPSs.However,Li et al.(129)identi?ed a corre-lation between loosely bound EPSs and the ?occulation and sedimentation features of activated sludge.

The SMPs are soluble cellular components secreted by cells during synthesis or excreted for uncertain purposes (130–133).These SMPs can be further classi?ed into two groups:substrate utilization-association products (UAPs),formed via substrate metabolism,and biomass-associated products (BAP),generated partly through biomass decay.Drewes and Croue (134)indicated that natural organic matter (NOM)in river water was signi?cantly similar to SMPs produced by wastewater treatment plants.However the aromatic moieties of the SMPs and NOM are of different origins.By adding glucose or glutamic acid solution to an activated sludge system,the aromaticity of SMPs contained in the ef?uent increases (135).

Most research treated EPSs and SMPs independently,as if no relationship existed.For example,Costerton et al.,(136,149)Nielsen et al.(121),Suther-land (137),Hsieh et al.(138),and Wingender et al.(119)analyzed EPSs and active biomass,whereas Furumui et al.(139),Namkung and Rittmann,(140)and Speitel et al.(141)examined the interactions between SMPs,biomass,and inert https://www.sodocs.net/doc/1510198053.html,spidou and Rittmann (118)observed that soluble EPSs are SMPs in sludge liquor.Hence,based on current research,soluble EPSs ?loosely bound EPSs ?SMPs (mixed liquor)6NOM (river water).Microbial Product Fouling

The EPSs are a complex mixture of proteins,carbohydrates,acid polysacchar-ides,lipids,DNA,and humic acid substances that surround cells and create a matrix of microbial ?ocs and ?lms (142).These EPSs have been identi?ed as the primary foulants in MBR processes (41,48,49,51,143).As noted by Rojas et al.(144),the speed of growth of microorganisms in MBR was negatively correlated with the amount of EPSs produced.The speci?c resist-ance of the membrane examined by Rojas et al.increased 10-fold when protein concentrations increased from 30to 100mg l 21.

Kim et al.(145)utilized powdered activated carbon (PAC)to adsorb soluble EPSs and,hence,increased the ef?uent ?ow rate from the membrane.Park et al.(146)enhanced the ?ltrate ?ux by adding PAC to an anaerobic MBR.

On the other hand,the SMPs had also been identi?ed as the principal membrane foulant in MBR systems (147,148).Cicek et al.(149)determined A.Ramesh et al.

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that the SRT can be adjusted to minimize the SMP level in mixed liquor.The role of SMPs in membrane fouling remains controversial.Lee et al.(44)indicated that supernatant,at most,contributed 37%of total resistance in membrane ?ltration.However,Bouhabila et al.(55)found that total resistance of ?ltration by the supernatant was 76%.Wisniewski and Grasmick (53)attributed roughly 50%of total resistance in ?ltration to supernatant SMPs.Lee et al.(91)observed that attached cells and the SMPs produced a dynamic membrane.The cells attached to the membrane spread,accompanied by production of EPSs,thus forming a bio?lm.Cells accumulated on the surface are relatively easily eliminated by washing.Consequently,controlling cell metabolism by altering membrane characteristics is essential to limiting membrane fouling.

Effects of NOM on membrane fouling has been thoroughly investigated (150–157).Natural organic matter has been differentiated into different fractions according to molecular weight (158),hydrophobicity (155,159,160),and GC-pyrolysis-MS (161,162).Among numerous NOMs the polysaccharides are an important foulant on membranes (161,162).Kwon and Lawler (163)determined different fouling rates for membranes with indi-vidual organic compounds,such as dextran,alginic acid,polygalacturonic acid,and tannic acid.Yuan and Zydney (164,165)investigated MF and UF membrane fouling by humic substances.Pretreatment utilizing coagulation,ozonation,activated carbon adsorption were applied to eliminate NOM prior to membrane ?ltration (166–169).Jiang et al.(170)demonstrated that utilizing pre-coagulation signi?cantly improves ?ltration of raw river water via the UF membrane since high-molecular weight humic substances and suspended particles were effectively removed.

EPS Fouling

Based on these ?ndings,membrane biofouling via microbial products plays a critical role in determining the feasibility of utilizing MBR.As demonstrated by Li et al.(129),only loosely bound EPSs,and not total EPSs,correlated with performance of ?occulation and sedimentation processes.This subsec-tion characterizes and compares the differences and similarities between tightly and loosely bound EPSs extracted from a wastewater sludge sample and compares,and reveals their individual ?lterability for further comparison.

A test sample was collected from the return sludge stream at the waste-water treatment plant for the Neili Bread Plant,Presidential Enterprise Co.,Taoyuan,Taiwan.The chemical oxygen demand (COD)and suspended solids (SS)data of the supernatant drawn from the sludge,measured via EPA Standard Methods,were 22.6and 14.3mg l 21,respectively.The percen-tage weight of dried solids in the sludge sample was 0.83%w /w,determined by weighing and drying at 1028C.Biofouling in Membrane Bioreactor 1355D o w n l o a d e d

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The sludge sample was ?rst dewatered by centrifugation at 6000g for 10min.The dewatered cake was then re-suspended in a 0.85%w /w NaCl solution with several glass beans,and then sonicated at 20kHz and 330W l 21for 2min,shaken horizontally at 120rpm for 10min,and sonicated again for an additional 2min.The liquor was centrifugated at 8000g for 10min to separate solids and liquor.The supernatant was added with 2volumes of acetone and maintained at 48C for 24h to precipitate soluble substances.The collected precipitate was called the loosely bound EPSs for the sludge sample.

The solids collected were resuspended in a 0.85%w /w NaCl solution,sonicated for 2min and then heated at 808C for 15mins.The remaining liquor was centrifugated at 12000g for 30mins for supernatant collection.The obtained supernatant was added with 2volumes of acetone and main-tained at 48C for 24h.The precipitate was collected and named the tightly bound EPSs in the sample.

The compositions of the loosely bound and tightly bound EPSs were compared utilizing a Fourier-transform infrared (FTIR)spectrophotometer (Perkin Elmer 1760,England;sample /KBr ?1/100,4000–400cm 21

at 4cm 21resolution for 100cycles),Auger /X-ray induced photoelectron spectroscopy (VG Microtech MT-500,England;magnesium K a X-ray source with electron food gun at 4eV),and matrix-assisted laser desorption /ionization time of ?ight mass spectrometry

(Bruker Daltonics

AutoFlexO `MALDI-TOF USA;using 2,5dihydroxybenzoic acid as matrix,

spectra acquired at positive ion linear re?ectance mode);and in surface charge and ?oc size using a zetasizer (Zetasizer 3000HS type A,Malverin,England).

Figure 1presents the zeta potentials of suspensions containing loosely or tightly bound EPSs as a function of pH.The zeta potentials of both EPSs were roughly 214mV at neutral pH.The isoelectric points (IEP)were located at around pH 2.5for tightly bound EPSs and 2.0for loosely bound EPSs.

Figure 2presents the size distributions of both EPSs.These EPSs have bidispersed distributions:300–500nm and 2600–4800nm for tightly bound;and,200–400nm and 800–1200nm for loosely bound EPSs.The size of the tightly bound EPSs was larger than that of the loosely bound EPSs.

Figures 3a and 3b present the IR spectra of loosely bound and tightly bound EPSs,respectively.For the loosely bound fraction,the characteristic peaks demonstrated the presence of polysaccharides,proteins,and lipids.Conversely,the tightly bound EPSs lacked peaks at 1656(amide 1,C 55O)and 1542(amide II,C-N tN-H)cm 21,indicating an absence of proteins.

Figure 4presents the XPS data for both EPSs.The binding energy distri-butions of C 1s and O 1s demonstrated that the EPSs were primarily composed of carbohydrates.Small amounts of lipids were detected in both EPSs,peaking at 284.5eV [C-(C-H)].The C 1s peaks at 286.72and 286.27eV in loosely bound and tightly bound EPSs suggest the presence of functional groups of A.Ramesh et al.

1356D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

C-O and C-N,respectively.The O 1s peaks in both EPSs were located at 531.7eV,demonstrating the existence of C-OH and C-O-C.Small amounts of nitrogen were also detected in XPS spectra,giving a C:N ratio of 26and 24for loosely bound and tightly bound EPSs,

respectively.

Figure 2.Size distributions of extracellular polymeric substances extracted from sludge samples.Biofouling in Membrane Bioreactor 1357D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

The MALDI-TOF-MS spectra (Fig.5)showed that EPSs were present as molecules ,1000Da in size.The major peaks detected for both samples were at similar locations,indicating that both had similar molecular weights of molecules.

In summary,the insoluble constituents of EPSs presented as ?ne particles of bidispersed size distributions (Fig.1)and of negative surface charge (Fig.2).The EPSs were aggregates composed of molecules with molecular weights ,1000Da (Fig.5),and shared similar chemical

compositions Figure 3.IR Spectra of extracellular polymeric substances extracted from sludge samples.(a)Loosely bound,(b)tightly bound.

A.Ramesh et al.1358D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

(Figs.3and 4).However,the tightly bound EPSs were large in size (Fig.1)and were de?cient in protein,as indicated by the IR spectrum (Fig.3b).

Figure 6presents the ?ltration tests for total sludge,and for the two EPS suspensions using a 0.4m m MF membrane subjected to 35mmHg vacuum.The ?ux declined with time,reaching steady-state ?ux at after 40–50min ?ltration.Filtration of tightly bound EPSs had lower resistance than that of loosely bound EPSs.This ?nding may result from the larger particle

size Figure 4.XPS Spectra of extracellular polymeric substances extracted from sludge samples.(a)Loosely bound,(b)tightly bound.

Biofouling in Membrane Bioreactor 1359D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

noted for the tightly bound EPS.When the total sludge sample was ?ltered,the initial ?ux was higher than that for the loosely bound EPS test,and declined rapidly over time,merging with the loosely bound EPSs after 10min of ?l-tration.Hence,?ltration resistance was primarily produced by the

loosely Figure 5.MALDI-TOF-MS spectra of extracellular polymeric substances extracted from sludge samples.(a)Loosely bound,(b)tightly bound.

A.Ramesh et al.1360D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

bound EPSs,but not by the tightly bound EPS.Experimental results indicate the signi?cant role of loosely bound EPSs on membrane fouling,and the need to remove it to minimize potential membrane fouling in full-scale applications.

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D o w n l o a d e d B y : [H a r b i n I n d u s t r y U n i v e r s i t y ] A t : 11:26 8 A u g u s t 2010

小学joinin剑桥英语单词汇总

JOIN IN 学生用书1 Word List Starter Unit 1.Good afternoon 下午好 2.Good evening 晚上好 3.Good morning 早上好 4.Good night 晚安 5.Stand 站立 Unit 1 6.count [kaunt] （依次）点数 7.javascript:;eight [eit] 八 8.eleven [i'levn] 十一 9.four [f?:] 四 10.five [faiv] 五 11.flag [fl?g] 旗 12.guess [ges] 猜 13.jump [d??mp] 跳 14.nine [nain] 九 15.number ['n?mb?] 数字 16.one [w?n] 一 17.seven ['sevn] 七 18.six [siks] 六 19.ten [ten] 十 20.three [θri:] 三 21.twelve [twelv] 十二 22.two [tu:] 二 23.your [ju?] 你的 24.zero ['zi?r?u] 零、你们的 Unit 2 25.black [bl?k] 黑色26.blue [blu:] 蓝色 27.car [kɑ:] 小汽车 28.colour ['k?l?] 颜色 29.door [d?:] 门 30.favourite [feiv?rit]javascript:; 特别喜爱的 31.green [gri:n] 绿色 32.jeep [d?i:p] 吉普车 33.orange ['?:rind?] 橙黄色 34.pin k [pi?k] 粉红色 35.please [pli:z] 请 36.purple ['p?:pl] 紫色 37.red [red] 红色 38.white [wait] 白色 39.yellow ['jel?u] 黄色 Unit 3 40.blackboard ['bl?kb?:d] 黑板 41.book [buk] 书 42.chair [t???] 椅子 43.desk [desk] 桌子 44.pen [pen] 钢笔 45.pencil ['pensl] 铅笔 46.pencil case [keis] 笔盒 47.ruler ['ru:l?] 尺、直尺 48.schoolbag [sku:l] 书包 49.tree [tri:] 树 50.window ['wind?u] 窗、窗口 Unit 4 51.brown [braun] 棕色 52.cat [k?t] 猫

常用二极管参数

常用整流二极管 型号VRM/Io IFSM/ VF /Ir 封装用途说明1A5 600V/1.0A 25A/1.1V/5uA[T25] D2.6X3.2d0.65 1A6 800V/1.0A 25A/1.1V/5uA[T25] D2.6X3.2d0.65 6A8 800V/6.0A 400A/1.1V/10uA[T60] D9.1X9.1d1.3 1N4002 100V/1.0A 30A/1.1V/5uA[T75] D2.7X5.2d0.9 1N4004 400V/1.0A 30A/1.1V/5uA[T75] D2.7X5.2d0.9 1N4006 800V/1.0A 30A/1.1V/5uA[T75] D2.7X5.2d0.9 1N4007 1000V/1.0A 30A/1.1V/5uA[T75] D2.7X5.2d0.9 1N5398 800V/1.5A 50A/1.4V/5uA[T70] D3.6X7.6d0.9 1N5399 1000V/1.5A 50A/1.4V/5uA[T70] D3.6X7.6d0.9 1N5402 200V/3.0A 200A/1.1V/5uA[T105] D5.6X9.5d1.3 1N5406 600V/3.0A 200A/1.1V/5uA[T105] D5.6X9.5d1.3 1N5407 800V/3.0A 200A/1.1V/5uA[T105] D5.6X9.5d1.3 1N5408 1000V/3.0A 200A/1.1V/5uA[T105] D5.6X9.5d1.3 RL153 200V/1.5A 60A/1.1V/5uA[T75] D3.6X7.6d0.9 RL155 600V/1.5A 60A/1.1V/5uA[T75] D3.6X7.6d0.9 RL156 800V/1.5A 60A/1.1V/5uA[T75] D3.6X7.6d0.9 RL203 200V/2.0A 70A/1.1V/5uA[T75] D3.6X7.6d0.9 RL205 600V/2.0A 70A/1.1V/5uA[T75] D3.6X7.6d0.9 RL206 800V/2.0A 70A/1.1V/5uA[T75] D3.6X7.6d0.9 RL207 1000V/2.0A 70A/1.1V/5uA[T75] D3.6X7.6d0.9 RM11C 1000V/1.2A 100A/0.92V/10uA D4.0X7.2d0.78 MR750 50V/6.0A 400A/1.25V/25uA D8.7x6.3d1.35 MR751 100V/6.0A 400A/1.25V/25uA D8.7x6.3d1.35 MR752 200V/6.0A 400A/1.25V/25uA D8.7x6.3d1.35 MR754 400V/6.0A 400A/1.25V/25uA D8.7x6.3d1.35 MR756 600V/6.0A 400A/1.25V/25uA D8.7x6.3d1.35 MR760 1000V/6.0A 400A/1.25V/25uA D8.7x6.3d1.35 常用整流二极管(全桥） 型号VRM/Io IFSM/ VF /Ir 封装用途说明RBV-406 600V/*4A 80A/1.10V/10uA 25X15X3.6 RBV-606 600V/*6A 150A/1.05V/10uA 30X20X3.6 RBV-1306 600V/*13A 80A/1.20V/10uA 30X20X3.6 RBV-1506 600V/*15A 200A/1.05V/50uA 30X20X3.6 RBV-2506 600V/*25A 350A/1.05V/50uA 30X20X3.6 常用肖特基整流二极管SBD 型号VRM/Io IFSM/ VF Trr1/Trr2 封装用途说明EK06 60V/0.7A 10A/0.62V 100nS D2.7X5.0d0.6 SK/高速 EK14 40V/1.5A 40A/0.55V 200nS D4.0X7.2d0.78 SK/低速 D3S6M 60V/3.0A 80A/0.58V 130p SB340 40V/3.0A 80A/0.74V 180p SB360 60V/3.0A 80A/0.74V 180p SR260 60V/2.0A 50A/0.70V 170p MBR1645 45V/16A 150A/0.65V <10nS TO220 超高速

常用二极管型号及参数大全精编版

1.塑封整流二极管 序号型号IF VRRM VF Trr 外形 A V V μs 1 1A1-1A7 1A 50-1000V 1.1 R-1 2 1N4001-1N4007 1A 50-1000V 1.1 DO-41 3 1N5391-1N5399 1.5A 50-1000V 1.1 DO-15 4 2A01-2A07 2A 50-1000V 1.0 DO-15 5 1N5400-1N5408 3A 50-1000V 0.95 DO-201AD 6 6A05-6A10 6A 50-1000V 0.95 R-6 7 TS750-TS758 6A 50-800V 1.25 R-6 8 RL10-RL60 1A-6A 50-1000V 1.0 9 2CZ81-2CZ87 0.05A-3A 50-1000V 1.0 DO-41 10 2CP21-2CP29 0.3A 100-1000V 1.0 DO-41 11 2DZ14-2DZ15 0.5A-1A 200-1000V 1.0 DO-41 12 2DP3-2DP5 0.3A-1A 200-1000V 1.0 DO-41 13 BYW27 1A 200-1300V 1.0 DO-41 14 DR202-DR210 2A 200-1000V 1.0 DO-15 15 BY251-BY254 3A 200-800V 1.1 DO-201AD 16 BY550-200～1000 5A 200-1000V 1.1 R-5 17 PX10A02-PX10A13 10A 200-1300V 1.1 PX 18 PX12A02-PX12A13 12A 200-1300V 1.1 PX 19 PX15A02-PX15A13 15A 200-1300V 1.1 PX 20 ERA15-02～13 1A 200-1300V 1.0 R-1 21 ERB12-02～13 1A 200-1300V 1.0 DO-15 22 ERC05-02～13 1.2A 200-1300V 1.0 DO-15 23 ERC04-02～13 1.5A 200-1300V 1.0 DO-15 24 ERD03-02～13 3A 200-1300V 1.0 DO-201AD 25 EM1-EM2 1A-1.2A 200-1000V 0.97 DO-15 26 RM1Z-RM1C 1A 200-1000V 0.95 DO-15 27 RM2Z-RM2C 1.2A 200-1000V 0.95 DO-15 28 RM11Z-RM11C 1.5A 200-1000V 0.95 DO-15 29 RM3Z-RM3C 2.5A 200-1000V 0.97 DO-201AD 30 RM4Z-RM4C 3A 200-1000V 0.97 DO-201AD 2.快恢复塑封整流二极管 序号型号IF VRRM VF Trr 外形 A V V μs （1）快恢复塑封整流二极管 1 1F1-1F7 1A 50-1000V 1.3 0.15-0.5 R-1 2 FR10-FR60 1A-6A 50-1000V 1. 3 0.15-0.5 3 1N4933-1N4937 1A 50-600V 1.2 0.2 DO-41 4 1N4942-1N4948 1A 200-1000V 1.3 0.15-0. 5 DO-41 5 BA157-BA159 1A 400-1000V 1.3 0.15-0.25 DO-41 6 MR850-MR858 3A 100-800V 1.3 0.2 DO-201AD

Joinin小学五年级英语教案

Join in 小学五年级英语教案 介休市宋古二中上站小学庞汝君 Unit 6 Friends 单元目标： 1、单词：sport music kite cap car book dog cat rat frog spider butterfly 2、句型：Who is your best friend ? （重点） How old is he ? When is his birthday ? What’s his favourite food ? 3、段落：介绍自己的好朋友 My best friend’s name is Toby . He is ten years old . His favourite colour is red . His birthday is in May . He has got a dog . 4、语法：第三人称的人称代词和物主代词（难点） 他he 他的his 她she 她的her 一般现在时第三人称单数动词+s

5、故事：Emma , Jackie and Diana . Are you all right ? What’s the matter ? Don’t be silly . We can play together . The first class 一、教学目标： 两个句型1、Who is your best friend ? 2、How old is he ? 二、教学过程： 1、Talk about your best friend . （1）教师说句子Who is your best friend ? My best friend is Anna. 让学生先领会句子的意思，然后模仿， 小组练习对话并上台表演。 （2）第二个句子How old is he ? He is nine years old . 象上面一样练习，等到学生掌握后把两个问句连起来做 问答操练。

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反向工作 峰值电压 URM/V 额定正向 整流电流 整流电流 IF/A 正向不重 复浪涌峰 值电流 IFSM/A 正向 压降 UF/V 反向 电流 IR/uA 工作 频率 f/KHZ 外形 封装
型 号
1N4000 1N4001 1N4002 1N4003 1N4004 1N4005 1N4006 1N4007 1N5100 1N5101 1N5102 1N5103 1N5104 1N5105 1N5106 1N5107 1N5108 1N5200 1N5201 1N5202 1N5203 1N5204 1N5205 1N5206 1N5207 1N5208 1N5400 1N5401 1N5402 1N5403 1N5404 1N5405 1N5406 1N5407 1N5408
25 50 100 200 400 600 800 1000 50 100 200 300 400 500 600 800 1000 50 100 200 300 400 500 600 800 1000 50 100 200 300 400 500 600 800 1000
1
30
≤1
＜5
3
DO-41
1．5
75
≤1
＜5
3
DO-15
2
100
≤1
＜10
3
3
150
≤0.8
＜10
3
DO-27
常用二极管参数： 05Z6.2Y 硅稳压二极管 Vz=6~6.35V,Pzm=500mW,

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理结束 →需带材料→工商营业执照正副本复印件原件→组织机构正副本原件及复印件→公章→公司法定代表人签署的《公司设立登记申请书》→公司章程→股东注册资金情况表→验资报告书复印件→场所证明（租赁合同）→法人身份证复印件原件→会计师资格证（劳动合同）→税务登记证办理结束 →需带材料→工商营业执照正副本复印件原件→组织机构正副本原件及复印件→税务登记证原件及复印件→公章→法人身份证原件及复印件→代理人身份证原件及复印件→法人私章→公司验资账户→注以上复印件需四份→办理时间个工作日→办理结束 →需带材料→工商营业执照正副本复印件原件→组织机构正副本原件及复印件→公章→公司法定代表人签署的《公司设立登记申请书》→公司章程→股东注册资金情况表→验资报告书复印件→场所证明（租赁合同）→法人身份证复印件原件→会计师资格证（劳动合同）→会计制度→银行办理的开户许可证复印件→税务登记证备案办理结束

三年级下学期英语(Joinin剑桥英语)全册单元知识点归纳整理-

Starter Unit Good to see you again知识总结 一. 短语 1. dance with me 和我一起跳舞 2. sing with me 和我一起唱歌 3. clap your hands 拍拍你的手 4. jump up high 高高跳起 5.shake your arms and your legs晃晃你的胳膊和腿 6. bend your knees 弯曲你的膝盖 7. touch your toes 触摸你的脚趾8. stand nose to nose鼻子贴鼻子站 二. 句子 1. ---Good morning. 早上好。 ---Good morning, Mr Li. 早上好，李老师。 2. ---Good afternoon. 下午好。 ---Good afternoon, Mr Brown. 下午好，布朗先生。 3. ---Good evening，Lisa. 晚上好,丽莎。 ---Good evening, Bob. 晚上好，鲍勃。 4. ---Good night. 晚安。 ----Good night. 晚安。 5. ---What’s your name? 你叫什么名字？ ---I’m Bob./ My name is Bob. 我叫鲍勃。 6. ---Open the window, please. 请打开窗户。 ---Yes ,Miss. 好的，老师。 7. ---What colour is it? 它是什么颜色？ 它是蓝红白混合的。 ---It’s blue, red and white. 皮特的桌子上是什么？ 8. ---What’s on Pit’s table? ---A schoolbag, an eraser and two books. 一个书包，一个橡皮和两本书。 9. ---What time is it? 几点钟？ 两点钟。 ---It’s two. 10.---What’s this? 这是什么？ ---My guitar. 我的吉他。

JOININ英语三年级下册知识点

JOIN IN英语三年级下册 Start unit 1 Words morning afternoon evening night 2 Sentences Good morning !早上好Good afternoon ！下午好Good evening！晚上好 Good night！晚安 3 Phrases clap your hands 拍拍手 jump up high 往高跳 shake your arms and your legs 晃动你的胳膊和腿 bend your knees 弯曲你的膝盖 touch your toes 摸摸你的脚指 stand nose to nose 鼻子对鼻子站着 Unit 1 Pets 1 Words cat猫dog狗bird 鸟mouse老鼠fish鱼rabbit 兔子frog青蛙hamster仓鼠 budgie鹦鹉tiger老虎monkey 猴子panda熊猫giraffe 长颈鹿elephant 大象bear 熊run跑sit坐fly飞swim游泳roar吼叫eat吃 2 Grammar

★名词的复数：一般在词尾直接加s,不规则变化要牢记: fish-----fish mouse------mice 3 Sentences 1.Have you got a pet ? 你有宠物吗？ Yes ,I have. 是的,我有。/No, I haven’t. 不，我没有。 2.What have you got ? 你有什么宠物吗？I’ve got a dog . / A dog. 我有一只狗。 3.What colour is the cat ? 你的猫是什么颜色的？It’s black. 它是黑色的。 What is wizard’s pet? 巫师的宠物是什么？ 4.What is it ? 它是什么? It’s a rabbit .它是只兔子。 5.How many budgies /mice are there? 这里有多少只鹦鹉/老鼠？ There are + 数字budgies/mice. 这里有------只鹦鹉/老鼠。 6.Fly like a budgie. 像鹦鹉一样飞。Run like a rabbit. 像兔子一样跑。 Swim like a fish. 像鱼一样游泳。Eat like a hamster. 像仓鼠一样吃东西。 Sit like a dog. 像狗一样坐。Roar like a tiger. 像老虎一样吼叫。 7.What are in the pictures. 图片里面是什么？Animals. 动物。 8. What animals? 什么动物？ 9.How many pandas (elephants /bears/ giraffes/ monkeys/ budgies) are there?有多少.？ How many + 可数名词的复数形式 Unit 2 The days of the week

很全的二极管参数

G ENERAL PURPOSE RECTIFIERS – P LASTIC P ASSIVATED J UNCTION 1.0 M1 M2 M3 M4 M5 M6 M7 SMA/DO-214AC G ENERAL PURPOSE RECTIFIERS – G LASS P ASSIVATED J UNCTION S M 1.0 GS1A GS1B GS1D GS1G GS1J GS1K GS1M SMA/DO-214AC 1.0 S1A S1B S1D S1G S1J S1K S1M SMB/DO-214AA 2.0 S2A S2B S2D S2G S2J S2K S2M SMB/DO-214AA 3.0 S3A S3B S3D S3G S3J S3K S3M SMC/DO-214AB F AST RECOVERY RECTIFIERS – P LASTIC P ASSIVATED J UNCTION MERITEK ELECTRONICS CORPORATION

U LTRA FAST RECOVERY RECTIFIERS – G LASS P ASSIVATED J UNCTION

S CHOTTKY B ARRIER R ECTIFIERS

S WITCHING D IODES Power Dissipation Max Avg Rectified Current Peak Reverse Voltage Continuous Reverse Current Forward Voltage Reverse Recovery Time Package Part Number P a (mW) I o (mA) V RRM (V) I R @ V R (V) V F @ I F (mA) t rr (ns) Bulk Reel Outline 200mW 1N4148WS 200 150 100 2500 @ 75 1.0 @ 50 4 5000 SOD-323 1N4448WS 200 150 100 2500 @ 7 5 0.72/1.0 @ 5.0/100 4 5000 SOD-323 BAV16WS 200 250 100 1000 @ 7 5 0.8 6 @ 10 6 5000 SOD-323 BAV19WS 200 250 120 100 @ 100 1.0 @ 100 50 5000 SOD-323 BAV20WS 200 250 200 100 @ 150 1.0 @ 100 50 5000 SOD-323 BAV21WS 200 250 250 100 @ 200 1.0 @ 100 50 5000 SOD-323 MMBD4148W 200 150 100 2500 @ 75 1.0 @ 50 4 3000 SOT-323-1 MMBD4448W 200 150 100 2500 @ 7 5 0.72/1.0 @ 5.0/100 4 3000 SOT-323-1 BAS16W 200 250 100 1000 @ 7 5 0.8 6 @ 10 6 3000 SOT-323-1 BAS19W 200 250 120 100 @ 100 1.0 @ 100 50 3000 SOT-323-1 BAS20W 200 250 200 100 @ 150 1.0 @ 100 50 3000 SOT-323-1 BAS21W 200 250 250 100 @ 200 1.0 @ 100 50 3000 SOT-323-1 BAW56W 200 150 100 2500 @ 75 1.0 @ 50 4 3000 SOT-323-2 BAV70W 200 150 100 2500 @ 75 1.0 @ 50 4 3000 SOT-323-3 BAV99W 200 150 100 2500 @ 75 1.0 @ 50 4 3000 SOT-323-4 BAL99W 200 150 100 2500 @ 75 1.0 @ 50 4 3000 SOT-323- 5 350mW MMBD4148 350 200 100 5000 @ 75 1.0 @ 10 4 3000 SOT-23-1 MMBD4448 350 200 100 5000 @ 75 1.0 @ 10 4 3000 SOT-23-1 BAS16 350 200 100 1000 @ 75 1.0 @ 50 6 3000 SOT-23-1 BAS19 350 200 120 100 @ 120 1.0 @ 100 50 3000 SOT-23-1 BAS20 350 200 200 100 @ 150 1.0 @ 100 50 3000 SOT-23-1 BAS21 350 200 250 100 @ 200 1.0 @ 100 50 3000 SOT-23-1 BAW56 350 200 100 2500 @ 70 1.0 @ 50 4 3000 SOT-23-2 BAV70 350 200 100 5000 @ 70 1.0 @ 50 4 3000 SOT-23-3 BAV99 350 200 100 2500 @ 70 1.0 @ 50 4 3000 SOT-23-4 BAL99 350 200 100 2500 @ 70 1.0 @ 50 4 3000 SOT-23-5 BAV16W 350 200 100 1000 @ 75 0.86 @ 10 6 3000 SOD-123 410-500mW BAV19W 410 200 120 100 @ 100 1.0 @ 100 50 3000 SOD-123 BAV20W 410 200 200 100 @ 150 1.0 @ 100 50 3000 SOD-123 BAV21W 410 200 250 100 @ 200 1.0 @ 100 50 3000 SOD-123 1N4148W 410 150 100 2500 @ 75 1.0 @ 50 4 3000 SOD-123 1N4150W 410 200 50 100 @ 50 0.72/1.0 @ 5.0/100 4 3000 SOD-123 1N4448W 500 150 100 2500 @ 7 5 1.0 @ 200 4 3000 SOD-123 1N4151W 500 150 75 50 @ 50 1.0 @ 10 2 3000 SOD-123 1N914 500 200 100 25 @ 20 1.0 @ 10 4 1000 10000 DO-35 1N4148 500 200 100 25 @ 20 1.0 @ 10 4 1000 10000 DO-35 LL4148 500 150 100 25 @ 20 1.0 @ 10 4 2500 Mini-Melf SOT23-1 SOT23-2 SOT23-3 SOT23-4 SOT23-5 SOT323-1 SOT323-2 SOT323-3 SOT323-4 SOT323-5