literature study for ultra filtration process

8/9/2019 Literature Study for Ultra Filtration Process

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Literature study for ultra ltration

process


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Table of Contents

1. Introduction..................................................................................................... 3

2. Membrane processes.......................................................................................3

3. Ultraltration process......................................................................................4

3.1. Dierent membranes material available and application.............................4

3.2. ypical U! membrane bre"material and application...................................#

3.2.1. $r%anic membranes..................................................................................#

&olyet'ersulfone.................................................................................................#

&olyacrylonitrile..................................................................................................#

&(D! )&olyvinylidine !louride*............................................................................ #

&olysulfone......................................................................................................... #

+ellulose acetate................................................................................................,

&olypropylene.....................................................................................................,

-ydrop'ilic &(D!................................................................................................,

-ydrop'obic membranes...................................................................................,

3.2.2. Inor%anic membranes...............................................................................,

+eramic membranes..........................................................................................,

3.3. $perational Mode )+ross o/ and Dead end operation*..............................0

3.3.1. Deadend mode........................................................................................0

3.3.2. +ross o/ mode........................................................................................

3.4. ecovery......................................................................................................

3.#. 5eneral problems e6perienced /it' U!......................................................17

Membrane foulin%................................................................................................17

3.,. &arameters used for lter control...............................................................11

3.,.1. +onstant u6 operation...........................................................................113.,.2. +onstant transmembrane pressure operation........................................12

3.0. +leanin% tec'ni8ues used..........................................................................13

3.. Membrane Module con%urations..............................................................14

3..1. ubular membrane.................................................................................. 14

3..2. &late and frame membranes...................................................................1#

3..3. -ollo/ !ibre membrane..........................................................................1#

3..4. 9piral /ound membrane.........................................................................1,

3.. Dierent suppliers of U! : dierent c'aracteristics....................................1,


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3.17. Membrane +osts.....................................................................................21

3.11. +ase studies............................................................................................23

3.12. eference................................................................................................2,


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1. Introduction

Membrane can be described as a thin layer of material that is capable of separating

materials as a function of their physical and chemical properties when a driving force is

applied across the membranes. In membrane separation processes, the feed is separatedinto a stream that goes through the membrane, i.e, the permeate and a fraction of feed that

does not go through the membrane, i.e., the retentate or the concentrate.

2. Membrane processes

Membranes processes can be classified into microfiltration, ultrafiltration, ninofiltration and

reverse osmosis. The classification is based on the membrane pore size or the size of

particle that can be retained by the membrane. Generally microfiltration membranes have

pore size range of 0.1 to !m, ultrafiltration has a range of 0.01"0.1!m, ninofiltration ranges

from 0.001"0.01!m and reverse range from 0.0001 to 0.001!m. #rror$ %eference source not

found shows the different membrane processes, pore size and impurities removed by each

process.

&igure 1$ different membrane processes and impurities removed.


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3. Ultrafiltration process

3.1.Different membranes material available and application

'ltrafiltration membranes can be made from organic (polymer) and inorganic materials.

*ommon polymeric materials used in '& include +olysulfone (+), +olyethersulfone (+#),

+olypropylene (++), or +olyvinylidenefluoride (+-&) and inorganic membranes can be

ceramics, glass, or metals.

3.1.1. Organic membranes and application

/rganic membranes can be hydrophilic or hydrophobic. ydrophilic membranes absorb

water and allow it to pass through yet hydrophobic membranes reects water molecules and

therefore need higher driving force to push water through.

ydrophilic membranes are water loving membranes which readily adsorb water. The

surface chemistry of these materials allow them to be wetted forming a water film on their

surface. ydrophilic membranes re2uire less operating pressure than hydrophobic

membranes. It has greater resistance to fouling. It is used for general filtration and

mycoplasma removal. The more hydrophilic the membrane surface is, the easier it is for

water to permeate.

ydrophobic means water"hating and these membrane materials have little or no tendency

to adsorb water. If the membrane surface becomes more and more hydrophobic it will

essentially stop to provide permeate flu3 and the process will come to a standstill.

Organic membranes material

+/45#T#%'4&67# M#M8%67#

+olyethersulfane membrane is highly hydrophilic. It has absolute removal of bacteria and

viruses. It is tolerant to solvents and resistant to many ethers and aromatics. These

membranes are mostly used in oil, food and permaceutical processes.


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+/456*%54/7IT%I4# M#M8%67#

+olyacrylonitrile membranes are tolerant to many solvents and oils. They are mostly used in

oil9water separation, treatment of grey water, blac: water, lignin and te3tile waste water.

+/45-I754II7# &4/'%I# (+-&)

+-& (+olyvinylidine &louride) membranes are highly o3idant tolerant and have moderate

p operating range. They have moderate temperature limits and e3hibit good mechanical

strength. It is a best choice for low pressure, high flu3 application. It has good heat stability

and is chemically resistant. It is suitable for waste water treatment, oil9water separation and

surface water treatment.

+/45'4&/7# M#M8%67#

These membranes are mostly used for +ost"Treatment of ultrapure water as well as

%emoval of suspended solids.

*#44'4/# 6*#T6T#

*ellulose acetate is the original membrane used for '& applications. The material has

number of limitations though with respect to p and temperature. It is hydrophilic which

ma:e it less fouling. This type of membrane can be eaten by microorganism. +olypropylene

membranes operate at wide p range (;"1


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3.2.Operational Mode (Cross flo and Dead end operation!

The direction of feed water flow, in relation to the membrane surface, determines the mode

of filtration in a membrane system. The modes of operation can either be a cross flow or a

dead"end mode. The two modes of operation may e3perience differences in fouling rate, flu3

and recovery, and finished water 2uality.

3.2.1. Dead"end mode

In a dead"end filtration system the feed water flows perpendicular to the membrane surface.

6ll the feed water becomes the permeate. The reect is periodically removed from the

system. In dead end operational mode, solids build up in the system, thus it is suitable for

less fouling applications. shows the flow of water in a dead end mode. The flow can be

e3presses as follows$

>feed ? >permeate

@here > ? &low rate

&igure ;$ chematic iagram howing ead "end mode of operation

3.2.2. Cross flo mode

In a cross flow system, the feed water flows parallel to the membrane surface. +ermeate is

collected through the sidewalls of the membrane. *ross flow systems are used with high

fouling feed. olids are continuously flushed from the system resulting in less fre2uent

bac:pulses and bac:washes, and possibly longer membrane life. 6 cross"flow system can


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also be operated on a dead end mode by simply closing the discharge valve. &igure show

the cross flow mode of operation. The flow on a cross flow can be e3pressed as follow$

>feed ?>permeate A >concentrate

&igure $ chematic diagram showing cross flow filtration mode

Table 1# $dvantages and Disadvantages of Dead"end and Cross flo operation

Dead %nd Cross &lo

$dvantages Disadvantages $dvantages Disadvantages4ow cost highly susceptible to

fouling

4ow recovery rate

due to separation

into filtered water

and concentrated

water

%elatively high

operating cost.

igh recovery rate &re2uent bac:wash

ma:es continuous

operation impossible

*ontinuous

operation

Treatment of

concentrated water is

re2uired

imple operation 4arge and

complicated unit


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3.3.'ecover

%ecovery is a term that is used to describe the amount of water that is treated versus the

amount of filtrate that is produced. It can be e3pressed as follows$

%ecovery ? >filtrate9>feed.

There is no mode of operation that will give 100B recorvery. #ven on dead"end mode there

is water that is used during bac:washes and flushes. It end up in the drain and it must be

accounted for.


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3.).*eneral problems e+perienced it, U&

Membrane fouling

&ouling is the most serious disadvantage of pressure"driven membrane separation

processes. &ouling can be classified into reversible and irreversible fouling depending on the

e3tent at which the foulants are attached to the membrane surface. %eversible fouling is

caused by gel layer that forms on the surface of a membrane. This is caused by reversible

concentration polarisation. This type of fouling can be removed by physical cleaning

methods. Irreversible fouling is when impurities gets absorbed or trapped inside the

membrane pores. It cannot be removed by physical method.

Membrane fouling results in a decrease in flu3 and an increase in energy consumption and

feed pressure. &ouling will occur in any '& system, regardless of the membrane polymer,

system manufacturer, and mode of operation. &ortunately, fouling can be effectively

controlled through the proper use of pre"treatment processes, chemical additions, and

proper system design and operation.

Membranes fouling typically manifests itself as a decline in permeate flu3 with time of

operation, and conse2uently, this is often accompanied by an alteration in membrane

selectivity. These changes often continue throughout the process and eventually re2uire

e3tensive cleaning or replacement of the membrane. It should be noted that the effect of

membrane fouling on the flu3 can often be very similar to those associated with

concentration polarization. &or this reason, it is first necessary to distinguish between

membrane fouling and concentration polarization, although both are not completely

independent of each other since fouling can result from polarization phenomena.

&lu3 decline can also be caused by changes in membrane properties as a result of physical

deterioration of the membrane and9or change in feed properties. evere fouling may also be

caused by seasonal algae bloom in the feed water. /ccasional pre"chlorination is necessary

for such cases. There are different types of fouling mechanisms. -iz$ inorganic, organic,

biological9microbial and colodial9particulate fouling.

Inorganic fouling


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Inorganic fouling" is caused by the accumulation of inorganic precipitates, such as metal

hydro3ides. +recipitates are formed when the concentration of these chemical species

e3ceeds their saturation concentrations.

-articulate Colloidal fouling

+articulate9 *olloidal fouling can be caused by impurities li:e algae, bacteria, and some

natural organic matter fall into the size range of particulate and colloids.

Microbialbiological fouling

Microbial9biological fouling is a result of formation of biofilms on membrane surfaces. uch

films grow and release biopolymers as a result of microbial activity. &or e3ample, once

bacteria attach to the membrane, they start to multiply and produce e3tracellular polymetric

substances (#+) to form a viscous, slimy, hydrated gel.

Organic &ouling

everal studies have shown that natural organic matter (7/M) is a maor culprit in '&

membrane fouling, and that different component of 7/M causes different forms of fouling.

3./.-arameters used for filter control

'& membrane filtration system control is governed by the fouling tendency of the feed. Transmembrane +ressure (TM+) and &lu3 are the parameters used to control the '& systems. 6

'& system can be operated at constant Trans"membrane and varying flu3, or constant flu3

and varying Trans"membrane pressure. It can be operated at ambient temperature, even

though at some occasions it is necessary to operate at considerable low temperature to

prevent the growth of microbiological organisms.

3./.1. Constant flu+ operation


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+ressure difference across the membrane is the indication of the e3tent of fouling. The TM+

is directly proportional to fouling. '& systems can be operated at constant flu3. The fouling of

the membrane will be indicated be an increase in trans"membrane pressure. These systems

have a set high TM+ limits which when reached the system re2uires cleaning. These

phenomena can be automated to protect the membranes from irreversible fouling.

&igure )# Constant flu+ operation

3./.2. Constant trans"membrane pressure operation

&lu3 is a term used to describe the filtration rate in membrane treatment. It is the rate of flow

per unit area of membrane, measured in litres per meter s2uared per hour (4M). It can be

e3pressed as follows$

Flux=Q

A

@here > ? volumetric flow rate across membrane

6? cross sectional area of membrane

It can also be used to indicate fouling of a membrane system. If the system is operated at

constant trans"membrane pressure, fouling of the membrane will be indicated by a decrease

in flu3. 6t constant TM+, the system will be run with flu3 dropping due to fouling. 6t a set

minimum flu3, the membranes will re2uire cleaning to recover the initial flu3. If the initial flu3


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is not achieved after cleaning, it will be an indication of irreversible fouling. &igure C show

flu3 vs time profile for a constant pressure operation.

&igure /# Constant Trans"membrane pressure operation


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3.0.Cleaning tec,niues used

The fouling on membrane surface results in reduction in flu3 or an increase in Trans"

Membrane +ressure (TM+). In order to have a continuous operation, membrane cleaning is

then re2uired. Membrane cleaning methods can broadly be classified into physical and

chemical cleaning. The choice of cleaning method depends of the type of fouling.

-,sical cleaning

+hysical cleaning is mostly re2uired to remove ca:e layer on membrane surface. +hysical

cleaning may include bac:washing, bac:"pulsation, air scrub, low pressure"high flow rate,

mechanical scrub, hot water cleaning and circulation spray cleaning.

C,emical cleaning

*hemical cleaning is used to remove organic and inorganic impurities on the membrane

surface. *hemicals used include acids and al:aline detergents, o3idants, enzyme

detergents, disinfectants, surfactants etc. 6cid detergents such as hydrochloric acid remove

inorganic impurities, whereas al:aline detergents, o3idant, such as sodium hydro3ide are

used to remove organic impurities, enzyme detergents are used to remove impurities such

as proteins and surfactants are used to remove oils. *hemicals are added in three

categories, vizD"

a) *hemical #nhanced 8ac:washing (*#8) " ere the chemical is added in the

bac:wash stream of water to assist the bac:wash.

b) *hemical addition " in this techni2ue a chemical is added on the feed to condition

it so that the fouling potential may decrease.

c) *hemical *leaning in +lace (*I+) " this step is ta:en when the membrane have

e3perienced severe fouling, it is aimed at removing all the contaminants. The

membrane process is stopped and the module is soa:ed in a chemical solution.

3..Membrane Module configurations

There are several module configurations used in membrane filtration. They include plate and

frame, tubular, hollow fibre and spiral wound. The emergence of the different configurations

has been to address the problem of membrane fouling. +late and frame and tubular

membrane were the first commercialised membranes. These membranes were e3pensive

and this limited their application. The development of low cost hollow fibre and spiral wound

membranes has increase the use of membrane filtration.


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&igure # -late and &rame membrane modules

3..3. ollo &ibre membrane

ollow &ibre membranes are made of 0.C to 1.Cmm diameter tubes stac: together into a

membrane module. &low through a hollow fibre membrane can be inside"out or outside"in

depending on solids content of the feed. If there are high solids, an outside"in flow is

preferred. 6n inside"out flow can be used if the size of the solids particles in the feed is less

than one tenth of the membrane diameter.

ollow fibre membrane can be in cross flow or dead end mode. If the feed is highly fouling, a

dead end arrangement can be used. #3tensive pre"treatment is not re2uired in hollow fibre

membranes since it can easily be bac:washed. ollow fibre can give a high throughput due

to e3tensive surface area and it cost less compared to plate and frame and tubular

membranes. &igure 4 shows a schematic diagram for hollow fibre membranes.

&igure 4# ollo &ibre membrane module


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3..). 5piral ound membrane

6 spiral wound membrane consists of a series of membrane leafs connected to a central

tube. #ach leaf consists of two membrane sheets oined together on the edges. 6 spacer is

incorporated in between the sheets. @ater flows from outside into the inside of the sheets. It

then flows through the central tube and then collected as permeate. These membranes can

not be bac:washed and therefore not suitable for highly fouling feeds. chematic diagram

for spiral wound membrane is shown in &igure 6.

&igure 6# 5piral 7ound membrane module

3.4.Different suppliers of U& 8 different c,aracteristics

Membrane manufactures that have full"scale operating M&9'& membrane drin:ing water

installations includes but not limited to ydranautics of /ceanside, *alifornia, Eoch

industries of @ilmington, elaware, 7orit 6mericas Inc. of 6tlanta, /ndeo"62uasource of

%ichmond, +all *orporation of +ort @ashington, 7.5, '& Memcor of turbridge, Mass,=enon #nvironment of /a:ville, Toronto, ow @ater and +rocess olutions,Toray

Membranes. ue to the dynamic and comple3 mar:et for M&9'& membranes and the almost

continuous development bringing new technologies and new suppliers to the drin:ing water

mar:et, listed here are few membrane manufacturers that are currently supplying M& and

'& membranes.

There are other suppliers who do not manufacture M&9'& membranes, but they design and

supply M&9'& systems for drin:ing water applications with successful installations. These


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includes &.8. 4eopold *ompany of =elienople, Ionics of @atertown, +*I ivision of ITT

anitaire of Milford, /hio, etc

9D'$:$UTIC5

ydranautics has developed and manufactures both spiral wound elements and hollow fiber

modules, including the 5%6cap low"pressure '& capillary membrane technology. In

1F0, hydranautics began providing reverse osmosis (%/) and nanofiltration (7&)

membrane separation technology to the drin:ing water industry. 6c2uired by 7itto en:o

*orporation in 1FH, ydranautics established its corporate head2uarters in /ceanside,

*alifornia.

ydranautics continuing commitment to research and technology resulted in the ongoing

development and updating of a range of specialized membrane products. The 5%6cap

'& modules provide more than C"log removal of pathogens, are fouling resistant, and are

o3idant tolerant. 5%6cap systems can be configured as stand"alone treatment, single

stage, or with other types of pre"treatment as well.

5%6cap capillary '& membrane fiber composition is a hydrophilic modified

polyethersulfone, a material that is resistant to organic fouling and is e3cellent barrier for

pathogen and colloidal removal. 5%6cap modules operate in direct flow or cross flow

modes, providing operational fle3ibility re2uired for variable feed 2uality. These membranescan be applied in groundwater, surface water and waste"water treatment. They are made

from hydrophilic polyethersufones (+#). They operate within p range of ;"1.

;OC M%M


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C,aracteristics of ;OC membrane sstems

Membrane type 'ltra filtration

Membrane material +olysulfone (+)

riving force +ressureMembrane nominal Molecular weight cut"off 100000 altons

Ma3imum inlet pressure 0psi (


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'&ilter Memcor is a world leader in the development, manufacturing, and application of

low"pressure membrane filtration for water and wastewater treatment. More than I:C

=enon #nvirontmental Inc. is a *anadian company head2uartered in /a:ville. =enon is

focused on providing membrane solutions for water treatment and distributes its products

and processes worldwide through a networ: of regional offices. It pioneered immersed

membranes in the early 1FF0s and has since developed a wide range of applications for

water and wastewater treatment.

=enons immersed membrane, called =ee@eed, is a hollow fiber with filtration from the

outside"in under gentle suction. They are asymmetric '& membranes that reect allsuspended and colloidal solids, including viruses. They are made from +-&, a strong,

chlorine"tolerant polymer.

DO7 7$T%' $:D -'OC%55 5O>UTIO:5

ow @ater K +rocess olutions (@K+) offerings are used throughout the world to

improve the 2uality of drin:ing water and the water thatLs critical to essential industrial

processes li:e chemical processing, power generation and the manufacturing of food and

pharmaceuticals. ow technology is also vital to desalination and water reclamation efforts

in communities with severe water shortages.

The /@ 'ltrafiltration module utilizes a double"walled hollow fiber (capillary) +-&

membrane which has a very small nominal pore diameter for +-& material that allows for

the removal of all particulate matter, bacteria and most viruses and colloids. espite the

small pore diameter, the membrane has a very high porosity resulting in a flu3 similar to that

of micro"filtration (M&) and can effectively replace M& in most cases.


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ystems designed with /@ 'ltrafiltration use an outside"in flow configuration which allows

for less plugging, higher solids loading, higher flow area and easy cleaning. The primary flow

design is dead"end filtration but the module can be operated using a concentrate bleed.

ead"end filtration uses less energy and has a lower operating pressure than the

concentrate bleed, therefore reducing operating costs.

TO'$9 M%M


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The company Inge Gmb develops innovative ultrafiltration technologies used in the

treatment of drin:ing water, process water, sea water and waste water. /ur systems purify

water by reliably removing bacteria, viruses, particles and suspended solids. inge is

constantly reaffirming its goal of ensuring consistently high 2uality for both our e3isting,

satisfied customers and potential future clients.

Inge Gmb was founded in the year ;000 and is head2uartered in the town of Greifenberg

near Munich in 8avaria. Its German head2uarters houses all the companyLs main operations

including development, production, mar:eting and sales. ince 6ugust ;011 inge has been

part of 86&, the worldNs leading chemical company.

#fficient and effective water treatment generally re2uires a combination of different methods

and technologies. This combination depends on the intended purpose of the cleaned water

(e.g. drin:ing water, industrial process water for power plants, etc.) as well as on the 2uality

and degree of contamination of the original water.

The dizzerO modules produced by Inge transform water into clean water. /ptimum flow

distribution, top"notch purification efficiency and variable operating modes at low pressure

ensure consistently high 2uality.


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3.6.Membrane Costs

The costs associated with a new membrane treatment facility can be grouped into four

categories i,e +roect management and administrative costs, Membrane procurement costs,

*onstruction costs as well as operational and maintenance costs.

-roAect Management and administrative costs

The following items are normally for the engineering and administrative effort associated with

a membrane filtration facility$

• +ilot testing

• #nvironmental assessment

• %egulatory permitting

• Membrane procurement


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• #ngineering design.

• *onstruction administration (services during construction and construction

management)

• 4egal and administrative fees

• &inancial administration and fees

Membrane procurement Costs

&or many proects, there is a competitive selection process that determines the successful

membrane e2uipment supplier. 6 maority of proects determine the supplier based on an

economic analysis using a present"worth analysis that considers both capital and operational

costs as part of the evaluation.

There are many variations of membrane procurement, but in general, the process can be

informal or formal. 6n informal process is one where the selection is made based on the

receipt of information provided by the e2uipment supplier. 6 more formal approach is to

prepare a detailed set of procurement documents and solicit proposals that comply with the

re2uirements of the specifications.

Membrane 5stem Capital Cost considerations

Typical costs that are generally associated with the e2uipment supply contract for the '&

e2uipment supplier include &eed and dosing pumps, trainers, Membrane units, 8ac:wash

e2uipment, +rocess air, *hemicals, *lean"in"place (*I+) facilities, 6ncillary e2uipment

(tan:s, valves, piping and instrumentation), +rogrammable logic controller (+4*) and

*66, #lectrical e2uipment including variable"fre2uency drives.

In the development or calculation of the capital cost for a proect, sometimes it is appropriate

to include costs for items that are outside the membrane procurement contract such costs

may include the following$

• *ost of a larger building or a more comple3 building structure

• *ost of a more comple3 motor control centre

• *ost for concrete that would be used to construct a membrane treatment basin

• *onsiderations for the installation of large"diameter or comple3 membrane system

interconnecting piping or ventilation systems


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• *ost for the installation of a constructed"in"place membrane unit

• *ost of hoisting e2uipment

Operational costs

/perational costs are those costs that capture the annual e3penses associated with the

operation of a membrane treatment facility. These costs include energy (feed9permeate

pumps, bac:wash pumps, process air, compressed air, cleaning and heating solutions),

chemical(+re"treatment, bac:washing, cleaning in place),membrane replacement,

e2uipment maintenance and repair, waste disposal and labour.

3.1B. Case studies

Case 5tud 1# (


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throughout the ' with this process alternative, pilot testing was performed to confirm the

application and optimize the treatment process prior to design. +ilot plant testing was

conducted during a ;"month period to determine the softening reactions and sludge

production, along with barium removal efficiency.

The softened9settled was fed to two pilot"scale '& units and one M& unit to optimize the flu3

rates through the membranes. &iltrate from the M&9'& units fed a two"stage %/ pilot system

using thin"film, composite polyamide, spiral"wound membranes. The pilot testing showed

that softening and membranes are not mutually e3clusive and in fact, softening can

significantly increase the recovery rate for the membrane process. The pilot testing also

showed that up to 0 percent removal of barium can be achieved through the lime"soda ash

softening process and that the M&9'& units effectively reduced the I below 1.C, which is

unacceptable level for %/. The pilot testing also confirmed the levels of antiscalant for the

%/ membranes.

6t the time of this case study, the '& system completed a ;"day performance test and was

concluding a 0"day acceptance test. uring the performance testing, the turbidity of the '&

permeate was continuously recorded below the guarantee of 0.10 7T', minimum

throughput and recovery re2uirements were e3ceeded, and a guaranteed ma3imum energy

consumption was not e3ceeded.

The '&9%/ integrated membrane system (IM) is one of the largest drin:ing water

production facilities in 7orth 6merica to use the lime"soda ash softening and recarbonation

pre"treatment processes upstream of '& and %/. 8ased on preliminary performance data of

the two systems following start"up, the 4G@6T now provides a reliable source of high"

2uality drin:ing water for the 8%6 customers.

Case 5tud 2$ (5eeEonE Mass."Iron and Manganese 'emoval -lant!

The ee:on: @ater istrict serves a population of appro3imately 1C00 and is located in

ee:on: )a town in 8ristol *ounty, Massachusetts, 'nited tates) appro3imately 1J :m east

of +rovidence, %.I. The groundwater source, under the influence of surface water, had been

e3periencing high levels of both iron and manganese over the past two decades. The

e3isting facility utilized an in"ground treatment system to inect o3ygenated water into the

ground to o3idize and settle both minerals. owever, this was only effective for two out of the

three e3isting gravel"pac:ed wells, resulting in reduced production capabilities.


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There were also concerns regarding the ;C0 to 00 percent overall increases in demand

during the summer months, surface water influences, and the need to achieve a prolonged

cleaning interval. +ilot tests were performed with the =enon =ee@eed C00 immersed '&

process to confirm its performance in comparison to three pressure filtration processes and

for approval by the state. The '& system proved to be the most successful at meeting the

2uality goals of 0.0mg94 of manganese and 0.01mg94 of iron and demonstrated the ability

to achieve the highest recovery (PFFB). Thus, a new immersed '& facility was constructed

and has been operational since 6pril ;001.

The '& membrane plant is effective in reducing iron and manganese to undetectable levels.

The '& membranes also provide a positive physical barrier to microorganisms. This

characteristic allowed the ee:on: @ater district to return to operation two well supplies that

were determined to be under the influence of surface waterD one had not been used since

1FHF and another had suffered surface water contamination in 1FFH.

The plant operates at a net flu3 of


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membrane fibers to control the accumulation of solids, reduce fouling, and allow for

continued filtrate production at rated capacity without e3cessive increase in transmembrane

pressure (TM+). Instrumentation and automation at the plant is typical for a membrane

facility with all maor operating parameters (flows, temperature, and pressures) monitored

along with feed and filtrate turbidity and particle counts.

The '& units have operated for more than 1; years on a continuous basis with little or no

downtime and in ;00 were in the process of being replaced. uring this period, the

membrane modules had been cleaned on the average of every J to 1; months, primarily

using an al:aline surfactant. The plant was operational year"round during that period with

finished water flows varying from C to ;;1 4+M, producing consistent finished water

2uality.

3.11. 'eference

@I#7#%, M.%., 67 Q."M. 46I7#. (1FFJ). *oagulation and membrane separation.

M644#-I644#, Q., +.#. /#7664, M. %. @I#7#%. @ater Treatment Membrane

+rocesses. American Water Works Association Research Foundation.

=#M67, 4.Q. 67 6.4. 57#5. (1FFJ). Microfiltration and 'ltrafiltration$ +rinciples and

6pplications, 1st edition. Marcel Dekker Inc., New York

M644#-I644#, Q., +.#. /#7664, M. %. @I#7#%. @ater Treatment Membrane

+rocesses. American Water Works Association Research Foundation.


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