Literature Study for Ultra Filtration Process
Transcript of 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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