Water Treatment: Where have we been and where are we going? · revolutionize water treatment...

R. Rhodes TrussellR. Rhodes TrussellTrussell Technologies, Inc.Trussell Technologies, Inc.

Pasadena, CAPasadena, CA

The Vernon L. The Vernon L. Snoeyink Snoeyink LectureLectureUniversityUniversity of Illinoisof Illinois

9 March 20059 March 2005

Water Treatment: WhereWater Treatment: Wherehave we been and where arehave we been and where are

we going?we going?

Outline of TalkOutline of Talk

oo The historical development of waterThe historical development of watertreatment technologytreatment technologyoo potable waterpotable wateroo municipal wastewatermunicipal wastewater

oo The impact of recent developments inThe impact of recent developments inmembrane technologymembrane technology

oo The problem of water quality and waterThe problem of water quality and waterdistributiondistribution

Where have we been in theWhere have we been in thetreatment of drinking water?treatment of drinking water?

The History of Water TreatmentThe History of Water Treatment

oo Early 19th centuryEarly 19th centuryoo The development of the worldThe development of the world’’s cities hads cities had

reached the point where epidemics of classicreached the point where epidemics of classicwater-borne disease become the biggest risk towater-borne disease become the biggest risk tocitizens living in those citiescitizens living in those cities

oo Why do I say the development of the worldWhy do I say the development of the world’’sscities cities ““had reached the pointhad reached the point””??

The History of Drinking Water TreatmentThe History of Drinking Water Treatment[and what we have accomplished][and what we have accomplished]

oo Early 19th century (continued)Early 19th century (continued)oo Because the development of our cities hadBecause the development of our cities had

become so dense that drinking water was oftenbecome so dense that drinking water was oftenexposed to significant contamination fromexposed to significant contamination fromhuman feceshuman feces

oo Because we had begun to address sanitationBecause we had begun to address sanitationproblems by using water to transport ourproblems by using water to transport ourpersonal wastes to the nearest watercourse (thepersonal wastes to the nearest watercourse (thefirst flush toilets were invented in 1775)first flush toilets were invented in 1775)

oo The principal epidemic diseases at issue were:The principal epidemic diseases at issue were:oo CholeraCholeraoo Typhoid feverTyphoid feveroo DysenteryDysentery

Classic Cholera wasClassic Cholera wasparticularly notableparticularly notable

The bug responsible: The bug responsible: Vibrio cholerae Vibrio cholerae (comma bacillus)(comma bacillus) taken fromtaken from historiquehistorique.net.net

Vibrio cholerae Vibrio cholerae (comma bacillus)(comma bacillus) taken fromtaken from historiquehistorique.net.net

Characteristics of the Disease:Characteristics of the Disease:•• Illness begins 2 to 3 days after exposureIllness begins 2 to 3 days after exposure•• The bacillusThe bacillus colonizes the small intestine. Once there, it releasescolonizes the small intestine. Once there, it releases

anan enterotoxin enterotoxin which causes intestinal cells to transport waterwhich causes intestinal cells to transport waterand electrolytes from blood and tissue into the intestineand electrolytes from blood and tissue into the intestine

•• Symptoms: No Fever, Explosive vomiting and diarrhea,Symptoms: No Fever, Explosive vomiting and diarrhea,abnormally low blood pressure, abnormally low bodyabnormally low blood pressure, abnormally low bodytemperature, muscle cramps - often shock; coma; death bytemperature, muscle cramps - often shock; coma; death bydehydrationdehydration

•• If the victim is not treated, the whole process can reachIf the victim is not treated, the whole process can reachcompletion in less than 24 hrs and the death rate is ~ 50%completion in less than 24 hrs and the death rate is ~ 50%

More:More:•• First pandemic is thought to have started in India in 1813First pandemic is thought to have started in India in 1813•• During the next 110 years cholera rampaged around the worldDuring the next 110 years cholera rampaged around the world

in six pandemics, killing hundreds of thousands each timein six pandemics, killing hundreds of thousands each time•• It is important to understand that the very survival of thisIt is important to understand that the very survival of this

classic form of cholera depends on a cross-connectionclassic form of cholera depends on a cross-connectionbetween drinking water and sewage; why?between drinking water and sewage; why?

-- The victim is rapidly immobilized (i.e.The victim is rapidly immobilized (i.e. the victim canthe victim can’’t expose thet expose thevictimvictim’’s friends by visiting them or preparing their food)s friends by visiting them or preparing their food)

-- There were few asymptomatic carriers (i.e. those who survive noThere were few asymptomatic carriers (i.e. those who survive nolonger shed the pathogen in their feces)longer shed the pathogen in their feces)

-- The infectious dose is huge (> 10The infectious dose is huge (> 1066 organisms) organisms)


More:More:•• This is the organism that Dr. John Snow studied when he first This is the organism that Dr. John Snow studied when he firstshowed the connection between drinking water and entericshowed the connection between drinking water and entericdisease in London (1854)disease in London (1854)


The History of Drinking Water TreatmentThe History of Drinking Water Treatment

oo The actions taken by engineers andThe actions taken by engineers andScientists responsible for safe water:Scientists responsible for safe water:Action 1.Action 1. Apply the sanitary principle, i.e. find aApply the sanitary principle, i.e. find a

source of water that has never been exposed tosource of water that has never been exposed tohuman wastehuman waste

oo This is a This is a ““go back to naturego back to nature”” principle principle(let(let’’s go get some waters go get some water that is still in its natural state, stillthat is still in its natural state, still

protected from the sins of man)protected from the sins of man)oo This principle is easily grasped and itThis principle is easily grasped and it

has broad appealhas broad appealoo We still find statements about usingWe still find statements about using

a a ““protected sourceprotected source”” throughout our throughout ourliterature todayliterature today


oo The actions taken by engineers andThe actions taken by engineers andScientists responsible for safe water:Scientists responsible for safe water:Action 1.Action 1. Apply the sanitary principle, i.e. find aApply the sanitary principle, i.e. find a

source of water that has never been exposed tosource of water that has never been exposed tohuman wastehuman waste

oo This is a This is a ““go back to naturego back to nature”” principle principle(let(let’’s go get some waters go get some water that is still in its natural state, stillthat is still in its natural state, still

protected from the sins of man)protected from the sins of man)oo And it works. There are dramaticAnd it works. There are dramatic

examples in our history where weexamples in our history where webuilt aqueducts to protectedbuilt aqueducts to protectedsupplies and the action dramaticallysupplies and the action dramaticallyimproved public health (NYC isimproved public health (NYC issuch an example)such an example)

oo The actions taken by engineers andThe actions taken by engineers andScientists responsible for safe water(contScientists responsible for safe water(cont’’d):d):

Action 2.Action 2. (less widely appreciated)(less widely appreciated) Use continuously Use continuouslypressurized water systemspressurized water systems

oo First advanced by ThomasFirst advanced by Thomas HawksleyHawksley,, BritianBritian’’ssleading water engineer in the time immediatelyleading water engineer in the time immediatelyfollowing Snowfollowing Snow’’s discovery:s discovery:

oo Previously water systems were often pressurizedPreviously water systems were often pressurizedintermittentlyintermittently

oo Hawksley Hawksley advocated that systems be continuouslyadvocated that systems be continuouslypressurized so that, in case of a leak:pressurized so that, in case of a leak:

oo Clean water can go outClean water can go outoo Contaminants canContaminants can’’t go int go in



Action 2.Action 2. (less widely appreciated)(less widely appreciated) Use continuously Use continuouslypressurized water systemspressurized water systems

oo First advanced by ThomasFirst advanced by Thomas HawksleyHawksley,, BritianBritian’’ssleading water engineer in the time immediatelyleading water engineer in the time immediatelyfollowing Snowfollowing Snow’’s discovery:s discovery:

oo Previously water systems were often pressurizedPreviously water systems were often pressurizedintermittentlyintermittently

oo Hawksley Hawksley advocated that systems be continuouslyadvocated that systems be continuouslypressurized so that, in case of a leak:pressurized so that, in case of a leak:

oo ItIt’’s the best means of cross-connection controls the best means of cross-connection control


oo Simultaneous compliance with these twoSimultaneous compliance with these twoprinciples, alone, is sufficient to end classicalprinciples, alone, is sufficient to end classicalwaterborne diseasewaterborne disease

oo Many cities gained protection by these methods. In theMany cities gained protection by these methods. In theU.S., some examples are: Los Angeles, New York City;U.S., some examples are: Los Angeles, New York City;Boston; San Francisco; Oakland, CA; Seattle, andBoston; San Francisco; Oakland, CA; Seattle, andPortland, OR.Portland, OR.

oo But, from the beginning, many other cities were not ableBut, from the beginning, many other cities were not ableto gain protection in this way because they did not haveto gain protection in this way because they did not haveaccess to a protected water supplyaccess to a protected water supply



Action 3.Action 3. This lead to the use of water treatment technologyThis lead to the use of water treatment technologyas a way to as a way to ““repurifyrepurify”” water that had been contaminated water that had been contaminated

oo Filtration was the first technology widely appliedFiltration was the first technology widely appliedoo Certainly the evidence of improvement in the purity of the waterCertainly the evidence of improvement in the purity of the water

after filtration is accessible to everyoneafter filtration is accessible to everyoneoo And this improvement in purity was supported by theAnd this improvement in purity was supported by the

observation that outbreaks did not occur when water wasobservation that outbreaks did not occur when water wassupplied from deep wellssupplied from deep wells

oo Early technologies: river-bank filtration (Early technologies: river-bank filtration (Aachen Aachen 1850s), dune1850s), dunefiltration (Netherlands mid-19filtration (Netherlands mid-19thth century), slow sand filtration century), slow sand filtration(Dárcy, 1854)(Dárcy, 1854)

oo Later technology: Coagulation (aluminum or iron salts),Later technology: Coagulation (aluminum or iron salts),sedimentation, rapid sand filtration (George Fuller, 1888)sedimentation, rapid sand filtration (George Fuller, 1888)



Action 3.Action 3. This lead to the use of water treatment technologyThis lead to the use of water treatment technologyas a way to as a way to ““repurifyrepurify”” water that had been contaminated water that had been contaminated



oo But filtration wasnBut filtration wasn’’t always reliable.t always reliable.oo Some groundwater supplies were shown to beSome groundwater supplies were shown to be

contaminatedcontaminatedoo Bacteria were also found in some filtered watersBacteria were also found in some filtered watersoo Today we know filtration removes between 50% andToday we know filtration removes between 50% and

99.9% of the bacteria in water99.9% of the bacteria in wateroo Heavily contaminated supplies require moreHeavily contaminated supplies require more

Action 3.Action 3. Repurification Repurification (continued):(continued):oo Disinfection had already found its way intoDisinfection had already found its way into

medical practice medical practice (1847 - Semmelweis, a Hungarian,(1847 - Semmelweis, a Hungarian,stopped puerperal fever in a Vienna hospital bystopped puerperal fever in a Vienna hospital byrequiring doctors to wash their hands in chlorinerequiring doctors to wash their hands in chlorinesolution)solution)

oo Around the beginning of the 20th Century,Around the beginning of the 20th Century,disinfectants, particularly chlorine began todisinfectants, particularly chlorine began toappear as a method of water treatmentappear as a method of water treatment



oo Disinfection became nearly universal by 1940Disinfection became nearly universal by 1940

Together; filtration and disinfection remain theTogether; filtration and disinfection remain thecore of modern water treatment todaycore of modern water treatment today


Action 3. Action 3. Repurification Repurification (continued):(continued):


oo The Middle of 20th centuryThe Middle of 20th century(About the time I was born)(About the time I was born)

oo Developed world:Developed world: Classical water-borne disease of Classical water-borne disease ofthe human-to-human fecal-oral route had beenthe human-to-human fecal-oral route had beeneliminated.eliminated.

oo The Undeveloped World:The Undeveloped World: Classic waterborne Classic waterbornedisease of the human-to-human fecal-oral routedisease of the human-to-human fecal-oral routeremained the chief cause of death among childrenremained the chief cause of death among children

oo In fact:In fact: a major distinguishing characteristic between a major distinguishing characteristic betweenthe developed world and the undeveloped worldthe developed world and the undeveloped worldbecame the general availability of safe drinking water.became the general availability of safe drinking water.

oo This basic situation remains unchanged todayThis basic situation remains unchanged today


oo Measurement of particulatesMeasurement of particulatesoo Jackson Candle (~5 turbidity units)Jackson Candle (~5 turbidity units)oo Light Scattering (~0.02 turbidity units)Light Scattering (~0.02 turbidity units)oo Particle size analysisParticle size analysis

oo OrganicsOrganicsoo Disinfection byproducts (1974)Disinfection byproducts (1974)oo Volatile organic chemicals: TCE, PCE, etc. (~1980)Volatile organic chemicals: TCE, PCE, etc. (~1980)oo Some herbicides and pesticides, e.g. Some herbicides and pesticides, e.g. atrazine atrazine (1980s)(1980s)oo Pharmaceuticals and personal care products (~1995)Pharmaceuticals and personal care products (~1995)

oo Developments during the 2Developments during the 2ndnd half of the 20 half of the 20thth

CenturyCentury were mostlywere mostly about understandingabout understandingcontaminants:contaminants:


oo PathogensPathogensoo Enteric bacteriaEnteric bacteria

oo mid 70s mid 70s CampylobacterCampylobacter jejuni jejuni (diarrhea)(diarrhea)oo ~ 1980~ 1980 Legionella pneumophila Legionella pneumophila (pneumonia)(pneumonia)oo mid 80s mid 80s Helobacter Helobacter pylori pylori (ulcers, stomach cancer)(ulcers, stomach cancer)oo Early 80s to present - pathogenic Early 80s to present - pathogenic E. coliE. coli (traveler (traveler’’s diarrheas diarrhea

to hemolyticto hemolytic uremic uremic syndrome)syndrome)




oo Enteric virusesEnteric virusesoo late 40s (Polio)late 40s (Polio)oo 1960s (Hepatitis)1960s (Hepatitis)oo 1980s (rotavirus)1980s (rotavirus)oo 1990s ( (1990s ( (norovirusnorovirus, adenovirus?,, adenovirus?, astrovirus astrovirus?)?)




oo Protozoa:Protozoa:oo Early 1980s - G. Early 1980s - G. lamblialamblia

oo Zoonotic Zoonotic (infects both animal and man)(infects both animal and man)oo More resistant to chlorineMore resistant to chlorine

oo Late 1980s - C. Late 1980s - C. parvumparvumoo AlsoAlso zoonoticzoonoticoo MUCHMUCH more resistant to chlorine more resistant to chlorine




Where have we been in theWhere have we been in thetreatment of municipaltreatment of municipal

wastewater?wastewater?

oo Beside the contamination of drinking water,Beside the contamination of drinking water,the original problem identified with municipalthe original problem identified with municipalwastewater discharge was oxygen depletionwastewater discharge was oxygen depletionin rivers and streamsin rivers and streamsoo BODBOD55 test - Royal Commission 1908 test - Royal Commission 1908oo Activated Sludge - Fowler, England 1914Activated Sludge - Fowler, England 1914oo Oxygen-Sag Curve - Streeter-Phelps 1925Oxygen-Sag Curve - Streeter-Phelps 1925

oo In the Clean Water Act in the 1970s, theIn the Clean Water Act in the 1970s, theemphasis was still on removal of BODemphasis was still on removal of BOD55 and andsuspended solidssuspended solids

The History of Wastewater TreatmentThe History of Wastewater Treatment

oo The impact of nutrients and eutrophicationThe impact of nutrients and eutrophicationbegan to become clear in the 1960sbegan to become clear in the 1960s

oo Cost-effective biological processes forCost-effective biological processes forremoval of phosphorous and nitrogen beganremoval of phosphorous and nitrogen beganto appear in the 1970s (Bernard), wereto appear in the 1970s (Bernard), wereperfected in the 1980s, and are being widelyperfected in the 1980s, and are being widelydeployed today.deployed today.


oo Perhaps one of the biggest dilemmas inPerhaps one of the biggest dilemmas indeveloped countries today is the control ofdeveloped countries today is the control ofendocrine disruptors, pharmaceuticals andendocrine disruptors, pharmaceuticals andpersonal care products.personal care products.

oo Today the edge in wastewater treatment isToday the edge in wastewater treatment isour need to address the treatment requiredour need to address the treatment requiredfor reusefor reuse


Now I want to moveNow I want to moveto a focus on the futureto a focus on the future

II’’d like to do that by looking at twod like to do that by looking at twotopics: 1) membranes in watertopics: 1) membranes in watertreatment and 2) the role of thetreatment and 2) the role of the

distribution systemdistribution system

We are in the beginning of a revolutionaryWe are in the beginning of a revolutionarychange in water treatment technologychange in water treatment technology

Membrane technology is at the heart ofMembrane technology is at the heart ofthat revolution.that revolution.

Membranes in water treatmentMembranes in water treatment

There are three areas in water treatmentThere are three areas in water treatmentwhere membrane technology is causingwhere membrane technology is causingmajor change:major change: Membrane filtrationMembrane filtration DesalinationDesalination Membrane bioreactorsMembrane bioreactors

Membrane Filtration:Membrane Filtration:oo Late 1950s - Applied to laboratory measurementsLate 1950s - Applied to laboratory measurementsoo Late 1960s - Applied to pasteurization of beveragesLate 1960s - Applied to pasteurization of beveragesoo 1990s - Introduced to treatment of drinking water and1990s - Introduced to treatment of drinking water and

the recycling of wastewaterthe recycling of wastewateroo The technology being used now is quite a bit moreThe technology being used now is quite a bit more

advance than that used earlier.advance than that used earlier.oo Not so much in its ability to remove contaminantsNot so much in its ability to remove contaminantsoo But in itBut in it’’s ability to cost-effectively deal with verys ability to cost-effectively deal with very

large volumes of waterlarge volumes of wateroo The key developments were in membraneThe key developments were in membrane

cleaning - prior to the 1990s most membranecleaning - prior to the 1990s most membranefilters were disposablefilters were disposable

Membranes in Water TreatmentMembranes in Water Treatment

Membrane Filtration:Membrane Filtration:oo During this generation, membrane filtration willDuring this generation, membrane filtration will

revolutionize water treatment practicerevolutionize water treatment practiceoo For the first time we have the potential to sterilize theFor the first time we have the potential to sterilize the

water; to completely eliminate all pathogenswater; to completely eliminate all pathogensoo No commercial membrane filtration system is quiteNo commercial membrane filtration system is quite

there today, but the technology is developing rapidlythere today, but the technology is developing rapidlyand the promise is there.and the promise is there.


Membrane Filtration:Membrane Filtration:oo What are the Challenges we face?What are the Challenges we face?

oo The resilience of membrane system designs must beThe resilience of membrane system designs must beimproved.improved.

oo most systems use thousands of hollow fibers and it ismost systems use thousands of hollow fibers and it iscommon for these fibers to fail via fatigue at certaincommon for these fibers to fail via fatigue at certaincritical points.critical points.


Membrane Filtration:Membrane Filtration:oo What are the Challenges we face?What are the Challenges we face?

oo The resilience of membrane system designs must beThe resilience of membrane system designs must beimproved.improved.

oo most systems use thousands of hollow fibers and it ismost systems use thousands of hollow fibers and it iscommon for these fibers to fail via fatigue at certaincommon for these fibers to fail via fatigue at certaincritical points.critical points.

oo The design of membrane filtration systems must becomeThe design of membrane filtration systems must becomemore uniform and consistent.more uniform and consistent. Right now an early userRight now an early userfaces two important risks:faces two important risks:

oo Early obsolescence - every manufacturer is constantlyEarly obsolescence - every manufacturer is constantlychanging its standard designchanging its standard design

oo Forced marriage - replacements and upgrades can onlyForced marriage - replacements and upgrades can onlybe obtained from the original manufacturer.be obtained from the original manufacturer.


Membrane Filtration:Membrane Filtration:oo What are the Challenges we face? (continued)What are the Challenges we face? (continued)


ooSystems for monitoring to verifySystems for monitoring to verifyperformance must be improved andperformance must be improved andstandards must be developedstandards must be developed

ooWe must gain a better understanding ofWe must gain a better understanding ofthe mechanisms of membrane foulingthe mechanisms of membrane fouling

oo Right now pilot studies must be doneRight now pilot studies must be doneon every water source before a designon every water source before a designcan be contemplated.can be contemplated.

Desalination:Desalination:oo Important advances have also occurred in anotherImportant advances have also occurred in another

membrane process, membrane process, reverse osmosisreverse osmosisoo Research funded by the U.S. Office of Saline Water inResearch funded by the U.S. Office of Saline Water in

the mid 1970s led to the development of the concept ofthe mid 1970s led to the development of the concept ofa thin film composite reverse osmosis membranea thin film composite reverse osmosis membrane

oo The original RO membranes invented by Loeb and Sourirajan atThe original RO membranes invented by Loeb and Sourirajan atUCLA in 1958 were asymmetrical membranes made entirely ofUCLA in 1958 were asymmetrical membranes made entirely ofcellulose-acetatecellulose-acetate

oo Salts were rejected by the dense layer on topSalts were rejected by the dense layer on top





oo The thin film composite membrane consisted of two layers: aThe thin film composite membrane consisted of two layers: avery thin rejection surface, designed to reject the target ionsvery thin rejection surface, designed to reject the target ionsand a very porous support layer designed to support theand a very porous support layer designed to support therejection surface while offering a minimum of hydraulicrejection surface while offering a minimum of hydraulicresistanceresistance





oo This design allows the design of the rejection surface and theThis design allows the design of the rejection surface and theporous substructure to beporous substructure to be optimized separatelyoptimized separately


Desalination:Desalination:oo By the mid 1990s several manufacturers had perfected commercialBy the mid 1990s several manufacturers had perfected commercial

products that follow the thin film composite concept.products that follow the thin film composite concept.oo They have continued to improve on these products until, today,They have continued to improve on these products until, today,

membranes with a salt rejection of 99.9% and higher are available;membranes with a salt rejection of 99.9% and higher are available;allowing the production of potable water from seawater in a singleallowing the production of potable water from seawater in a singlepasspass

oo Also numerous innovations in energy recovery, etc. have made theAlso numerous innovations in energy recovery, etc. have made theoverall process more energy efficientoverall process more energy efficient

oo As a result, during the past decade, reverse osmosis has displacedAs a result, during the past decade, reverse osmosis has displacedthermal processes as the process of choice for desalination and athermal processes as the process of choice for desalination and anumber of new projects are in developmentnumber of new projects are in development


S/m3

Desalination:Desalination:oo Challenges remain here as well:Challenges remain here as well:

oo Pretreatment - the processes required for the pretreatment ofPretreatment - the processes required for the pretreatment ofseawater to make it suitable for reverse osmosis are notseawater to make it suitable for reverse osmosis are notadequately understoodadequately understood

oo Boron - current membrane technology produces water with aBoron - current membrane technology produces water with aboron level that is rather high (0.5 to 1.5 mg/L). The significanceboron level that is rather high (0.5 to 1.5 mg/L). The significanceof boron at these levels needs to be better understood andof boron at these levels needs to be better understood andboron removal needs to be further optimized.boron removal needs to be further optimized.

oo Corrosion - desalted water is corrosive and conventional methodCorrosion - desalted water is corrosive and conventional methodof adjusting CaCOof adjusting CaCO33 saturation is costly and hardens the water saturation is costly and hardens the water

oo Distribution - desalted water is produced on the coast and at seaDistribution - desalted water is produced on the coast and at sealevel and existing water distribution systems are designed tolevel and existing water distribution systems are designed totake the water in the opposite direction.take the water in the opposite direction.

oo Fouling - the forms of fouling in seawater desalting are notFouling - the forms of fouling in seawater desalting are notadequately understoodadequately understood


Membrane BioreactorsMembrane Bioreactorsoo Membrane filtration technologies haveMembrane filtration technologies have

also been successfully applied to thealso been successfully applied to thesolids separation step in the activatedsolids separation step in the activatedsludge processsludge process

oo This innovation results in severalThis innovation results in severalimportant improvements:important improvements:oo The quality of the effluent is vastlyThe quality of the effluent is vastly

improved as illustrated in theimproved as illustrated in the tabletable below:below:


Conventional Activated

Sludge

Membrane Bioreactor

SS 5 to 10 < 0.1

Turbidity 2 to 5 < 0.1

coliform10,000 to 100,000

ND to 100

Membrane BioreactorsMembrane Bioreactorsoo Membrane filtration technologies haveMembrane filtration technologies have

also been successfully applied to thealso been successfully applied to thesolids separation step in the activatedsolids separation step in the activatedsludge processsludge process

oo This innovation results in severalThis innovation results in severalimportant improvements:important improvements:oo The quality of the effluent is vastly improvedThe quality of the effluent is vastly improved

as illustrated in theas illustrated in the tabletable below:below:oo The process biology does not have to beThe process biology does not have to be

operated to produce aoperated to produce a settleable settleable sludgesludgeoo The process can operate at a much higherThe process can operate at a much higher

organic loading (requires less space)organic loading (requires less space)oo Produces an effluent that can go directly toProduces an effluent that can go directly to

RORO


Membrane BioreactorsMembrane Bioreactorsoo Membrane bioreactors also have their challenges:Membrane bioreactors also have their challenges:oo When conventional biological processes fail theWhen conventional biological processes fail the

water continues to pass through the plant but thewater continues to pass through the plant but thequality is unacceptablequality is unacceptable

oo When a membrane bioreactor fails the qualityWhen a membrane bioreactor fails the qualityremains high but the water fails to pass through theremains high but the water fails to pass through theplant (fouling)plant (fouling)

oo As unacceptable as conventional failure is, thisAs unacceptable as conventional failure is, thisnew type of failure is even worsenew type of failure is even worse


Membrane BioreactorsMembrane Bioreactorsoo Other challengesOther challenges

oo Gaining a better understanding of the causes ofGaining a better understanding of the causes ofmembrane fouling and how they can be controlledmembrane fouling and how they can be controlled

oo Developing the basic rules for the operation of theDeveloping the basic rules for the operation of theprocessprocess

oo Understanding how to design the process so that anUnderstanding how to design the process so that aneasily dewatered sludge is producedeasily dewatered sludge is produced

oo Designing better oxygen transfer in these high solidsDesigning better oxygen transfer in these high solidssystemssystems

oo Exploring the ability of MBR to remove Exploring the ability of MBR to remove xenobioticsxenobiotics


Now a look forwardNow a look forward

oo As population increases the impact of human activity willAs population increases the impact of human activity willbecome evident in even the most protected drinking waterbecome evident in even the most protected drinking watersourcessources

oo Likewise the pressure of population growth will force us toLikewise the pressure of population growth will force us touse (and reuse) increasingly compromised water sourcesuse (and reuse) increasingly compromised water sources

oo As detection limits go lower we will find that there areAs detection limits go lower we will find that there areanthropogenic chemicals in every water sourceanthropogenic chemicals in every water source

oo Regulation of municipal waste discharge and non-pointRegulation of municipal waste discharge and non-pointpollution will become intimately and formally connected withpollution will become intimately and formally connected withregulation of drinking water qualityregulation of drinking water quality

oo Increasingly the issues will be the same with allIncreasingly the issues will be the same with alldrinking water sources, protected or notdrinking water sources, protected or not

The future in the developed worldThe future in the developed world

oo We are using a distribution network sized toWe are using a distribution network sized tohandle irrigation and fire-flows to transport highhandle irrigation and fire-flows to transport highquality drinking waterquality drinking water

oo We are also using the same high quality waterWe are also using the same high quality waterfor all these purposes as well.for all these purposes as well.

oo We are irrigating our lawns with highly treatedWe are irrigating our lawns with highly treatedwater that is designed to be pathogen free,water that is designed to be pathogen free,odor free - even free of low level, long-termodor free - even free of low level, long-termchronic riskchronic risk

The way we distribute water will become aThe way we distribute water will become astrategic issue:strategic issue:


oo When we want to consider the use of recycledWhen we want to consider the use of recycledwastewater we build a separate infrastructure of similarwastewater we build a separate infrastructure of similarcapacity that is used only for irrigationcapacity that is used only for irrigation

oo In Southern California today, we are surrounded byIn Southern California today, we are surrounded bythat kind of infrastructurethat kind of infrastructure

oo Providing such infrastructure is expensive in newProviding such infrastructure is expensive in newdevelopments, but it isdevelopments, but it is much more expensive andmuch more expensive andmuch more intrusive when it must be built in older,much more intrusive when it must be built in older,existing neighborhoodsexisting neighborhoods

oo IsIs this approach economical and sustainable?this approach economical and sustainable?

The way we distribute water will become aThe way we distribute water will become astrategic issue:strategic issue:


oo In developed countries, we have reached the point where ourIn developed countries, we have reached the point where ourstrategy for distribution of water in municipalities is one of thestrategy for distribution of water in municipalities is one of theprinciple limits on our ability to provide the consumer with betterprinciple limits on our ability to provide the consumer with betterwaterwater

oo We have reached the point where we can make drinking water ofWe have reached the point where we can make drinking water ofextremely high quality at the treatment plantextremely high quality at the treatment plant

oo Increasingly, the challenge we face is finding ways to deliver thatIncreasingly, the challenge we face is finding ways to deliver thatwater to the consumer without compromising its high qualitywater to the consumer without compromising its high quality

oo HawksleyHawksley’’s s idea of continuously pressurized systems, while stillidea of continuously pressurized systems, while stillessential, is not enough if we are using a large, old distributionessential, is not enough if we are using a large, old distributionsystem with long detention timessystem with long detention times

Water distribution, a strategic issue:Water distribution, a strategic issue:(continued)(continued)




oo Perhaps we should consider another kind ofPerhaps we should consider another kind ofdual system?dual system?oo The existing distribution system for The existing distribution system for ““semi-semi-

potablepotable”” water wateroo All short-term risks removed (i.e.,All short-term risks removed (i.e.,

pathogens)pathogens)oo Source not necessarily protectedSource not necessarily protectedoo Long-term chronic risks and aestheticLong-term chronic risks and aesthetic

concerns not fully addressedconcerns not fully addressed



oo If we do that, what will we do for potable water? If we do that, what will we do for potable water?oo Perhaps we build a tiny parallel system forPerhaps we build a tiny parallel system for

drinking water made of special materialsdrinking water made of special materialsoo Low flow, but protected source and/or Super-Low flow, but protected source and/or Super-

TreatedTreatedoo Long-term chronic risks and aestheticLong-term chronic risks and aesthetic

concerns fully addressedconcerns fully addressedoo One or two taps in each home - clearlyOne or two taps in each home - clearly

identified as identified as potablepotable



oo Perhaps we will provide Perhaps we will provide ““drinking water stationsdrinking water stations””oo Special stations or kiosks could be built whichSpecial stations or kiosks could be built which

take water from the legacy system and give ittake water from the legacy system and give it““super treatmentsuper treatment””

oo Citizens drive by for a free fill-up and take theCitizens drive by for a free fill-up and take thewater homewater home

oo Both the private sector and the public sectorBoth the private sector and the public sectormight compete to offer these servicesmight compete to offer these services

oo Publicly provided bottled water is another possibilityPublicly provided bottled water is another possibility

I think we can beI think we can beassured of one thingassured of one thing

The next generation will would be wise toThe next generation will would be wise togo beyond models we use todaygo beyond models we use today

fiinisfiinis

puerperal fever, an aggressive infection ofpuerperal fever, an aggressive infection ofthe reproductive system following childbirth.the reproductive system following childbirth.

The infection - most commonly the bacteriaThe infection - most commonly the bacteriastaphylococcus and streptococcus - wasstaphylococcus and streptococcus - wasoften carried on the dirty hands and medicaloften carried on the dirty hands and medicalinstruments of doctors and midwives.instruments of doctors and midwives.

Water Treatment: Where have we been and where are we going? · revolutionize water treatment...

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