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INDION ®
OPERATION MANUAL INDION REVERSE OSMOSIS PLANT
STANDARD SYSTEMS DIVISION
Plot No. L-48 & L-49, Verna Electronic City, Phase II, Verna – Salcete, Goa – 403 722.
1.1 How do you rate our product quality product performance?
Please give instances where product performance was not up to the mark with complete details and actions taken.
1.2 How do you rate our products w.r.t. aesthetics in comparison with the competition
Please give details where competitor product is better than ours.
1.3
How do you rate our product range in comparison with competition.
Please suggest any product we may consider to be included in our product range
2 Packing 2.1
How you rate packing of our product
Please give instances where packing was not satisfactory and your suggestions for improvement.
2.2
How do you rate product label of our packing
Please give suggestions for improvement
3 Timely Despatches 3.1 Do you get despatches on time
Please give instances where despatches were delayed
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(10%) (100%) 1
2
3
4
5
6
7
8
9
10
4 Communication from factory
4.1 Are you happy with the promptness of communication from factory on your specific queries
Please give instances when communication from factory was not prompt.
4.2 Do you receive despatch details on time
5 Despatch of Documentation
5.1 Are you happy with the quality of documentation received from factory such as invoice
Please give instances where documentation was not upto the mark
5.2 How do you rate ‘User Manuals’ supplied along with the product
Please give your suggestions for improvement
6 Customer Complaint
6.1 Do you get prompt response from factory for the complaints
Please give instances when response was not so prompt
6.2 Are complaints resolved to your satisfaction from the factory
Please give instances
7 General
7.1 Please give your suggestion for improvements
………NOTE: ………
Please fill up the customer feedback form and send it to the following address. ADDRESS: ION EXCHANGE (INDIA) LTD., Phase II, Plot No. L-48 / 49, Verna Electronic City, Verna – Salcete, Goa – 403722. Telephone: 0832 – 2783159 / 60 Fax : 0832 – 2783158 Email: [email protected]
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1
WARRANTY CERTIFICATE
OUR CONTRACT NO. / UNIT SL. NO.: DEALER – NAME / LOCATION: CUSTOMER – NAME / LOCATION: PLANT DESCRIPTION
We hereby warrant that the unit/ equipment shall be free from defective material and faulty workmanship, subject to the following clauses. 1. Our liability in respect of any defect or failure of any equipment supplied by us
or any loss, injury or damage attributable thereto is limited to making good by way of replacement or rectification, defects which show up under proper use therein, provided the equipment is operated and maintained strictly in accordance with our instructions and arise entirely from proven faulty design, material or workmanship, within a period of 12 months from date of commissioning of equipment or 18 months from the date of last major supply, whichever is earlier. At the end of this period all our liabilities will cease. Under this warranty.
a). We shall have the right to make any replacement or repairs that is
required either at site or one of our factories. In case of a replacement, buyer shall return the replaced part/component to us within 7 (seven) days.
b). The warranty period for the entire planet including the replace/repaired
part will be limited to the remaining, unexpired portion of the total warranty period. Electrical components such as conductivity/pH meters, motors, contractors, PLCs, relays, solenoid valves, pressure switches & flow meters, rubber components and instruments such as pressure gauges, thermometers and rotameters are not covered under this warranty.
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:2:
c). Where equipment is ready for dispatch but cannot be dispatched due to
reasons attributable to the buyer, the warranty period will be 18 months from date of readiness for dispatch as notified by us in writing.
d). No. other party or agency may carry out replacements or repairs unless
authorized by us in writing.
e). If a part/component is to be replaced or repaid under this warranty, there will be no charge for the replacement. However, the travel and conveyance as well as boarding & lodging expenses incurred by our representative deputed for this work will be charged to the buyer at actuals.
f). This warranty does not cover replacement/repairs required as a result of
normal wear & tear, accidents or damages/defects caused by misuse/maloperation of the equipment by the buyer.
g) We recommend to use only our INDION & INDFLOC range of products
for chemical treatment during the warranty period.
2. This warranty is void if:-
a) The unit / equipment are put to wrong use / application. b) The unit / equipment are installed / commissioned by any person /
agency not authorized by us.
c) The unit is not installed / operated / maintained as per instructions given in our operation manual and / or those given by our authorized representative.
d) The operating conditions and influent water quality are other than
those for which the unit / equipment was supplied.
e) The monthly plant operating data for Reverse Osmosis (RO) plants is not sent in the following month to our concerned/office/our service company’s nearest office.
f) The agreed / contract price and installation charges, if any, have not
been paid to us / our dealer.
ION EXCHANGE (INDIA) LTD
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INDEX
Section Page
1. OVERVIEW AND INTRODUCTION ................................................................................................. 7
10. INDION EASY TEST KIT .................................................................................................................... 41
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1.1 INDUSTRIAL REVERSE OSMOSIS UNIT & CLEANING SYSTEM
INDION Reverse Osmosis units offer the advantages of modular design, compactness, flexibility and ease of operation. They can handle varying water compositions and a wide flow range. Availability of standard pretreatment units such as filters, post treatment units such as degasser systems and accessories such as dosing systems makes a total system solution possible to meet the exact requirements of a customer.
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2.0 DESCRIPTION
INDUSTRIAL REVERSE OSMOSIS UNIT & CLEANING SYSTEM
This section describes the process of desalination by reverse osmosis (RO) and the main equipment used.
2.1 Impurities in water The two sources of water for industrial use are: Surface water - drawn from lakes, rivers or sea Ground water - drawn from borewells, springs or artesian wells. Water drawn from these sources contains both undissolved and dissolved impurities. Undissolved impurities are removed by processes such as coagulation, clarification and filtration. Dissolved impurities are removed by processes such as distillation, electrodialysis, reverse osmosis and ion exchange.
2.2 Osmosis and Reverse Osmosis Osmosis is a natural process involving fluid flow across a semipermeable membrane barrier. It is selective in the sense that the solvent passes through the membrane at a faster rate than the dissolved solids. The difference of passage rate results in solvent solids separation. The direction of solvent flow is determined by its chemical potential, which is a function of pressure, temperature and concentration of dissolved solids. Pure water in contact with both sides of an ideal semipermeable membrane at equal pressure and temperature has no net flow across the membrane because the chemical potential is equal on both sides. If a soluble salt is added on one side, the chemical potential of this salt solution is reduced. Osmotic flow from the pure water side across the membrane to the salt solution side will occur until the equilibrium of chemical potential is restored. Equilibrium occurs when the hydrostatic pressure differential resulting from the volume changes on both sides is equal to the osmotic pressure. This is a solution property independent of the membrane. Application of an external pressure to the salt solution equal to the osmotic pressure will also cause equilibrium. Additional pressure will raise the chemical potential of the water in the salt solution and cause a solvent flow to the pure water side, because it now has a lower chemical potential. This phenomenon is called reverse osmosis. In the reverse osmosis process, the water that passes through the membrane is commonly referred to as permeate or product water, the water that remains behind the membrane along with dissolved and suspended solids is referred to as the concentrate, brine or reject water. We have used these terms interchangeably in this manual.
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Pressurised feed water is introduced into one end of the pressure tube. Some of the water, driven by the feed pressure through the RO pressure tube feed port permeates through the membrane, passes into the product tube and exits the pressure tube from the pressure tube product port as product water, less most of the dissolved solids and all of the suspended solids. The remainder of the water passes along the surface of the membrane with the concentrated dissolved and suspended solids and passes out of the pressure tube concentrate port as concentrate, brine or reject. The pressure tubes are generally arranged in stages when more product water is desired than one module can produce. The staging of the modules is designed to optimise the water flow patterns across the surface of the membrane. This uniform water flow promotes good flushing velocity across the membrane surface to prevent the accumulation of suspended solids on the surface which would foul the membrane and reduce the productivity. Multiple stages are referred to as arrays. Different ions also pass through the membrane to different extents depending on various factors such as valency, ionic size, concentration, etc. Therefore, the product water does have some salts, usually approximately 10% of the salts in feed water. Salt passage is defined as the ratio of total dissolved solids (TDS) in permeate to TDS in feed water. A certain minimum reject water flow is always maintained to flush the membrane surface and also keep certain sparingly soluble salts below their solubility limits. As a result, the ratio of the product water or permeate flow to feed water flow, called the recovery, is always less than 1.0.
2.3 Equipment Description
Please see the enclosed flow diagram for further clarity regarding the various components that make up the Reverse Osmosis Plant. The following gives brief description regarding the major components:
2.3.1 Pretreatment cartridge filter (CF)
The Cartridge Filter which is installed upstream of the high pressure pump removes particulate matter upto 5 microns from the feed water and minimizes the fouling of the RO membrane elements. 2.3.2 High pressure pump
A high pressure pump of stainless steel construction is provided to boost the feed pressure for the reverse osmosis membrane. A low pressure switch is provided at the pump suction to safeguard the pump. A stainless steel globe/ball valve is provided on the pump discharge for regulating the pressure and flow to the reverse osmosis membrane.
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A pressure gauge is provided upstream of this valve to monitor the pump performance. 2.3.3 Reverse Osmosis system
Basically the system consists of Reverse Osmosis membranes, pressure vessels (called pressure tubes) in which the membranes are mounted and piping for feed, reject and product with necessary instruments.
A cut-away view of the Reverse Osmosis membranes shows the details of the spirally wound configuration. The feed water is applied at one end of the membrane at high pressure. Because of the high pressure, reverse osmosis process takes place and permeate flows through the membrane and is collected through the core tube and normally flows out of the end opposite the feed. The reject is also collected from the opposite side. In order to maximise the recovery, a number of membranes are put end-to-end in a pressure tube made of FRP. The pressure tube is designed to withstand the pressure at which the RO system has been designed. To further improve the recovery, a number of pressure tubes are arranged in different combinations in such a way that the reject from the first "stage" becomes the feed for the next, and so on. Permeate is normally collected in a parallel manner from all the pressure tubes. The exact arrangement of staging would depend on the raw water characteristics and the desired treated water quality. High pressure piping with necessary fittings is provided for the above purpose.
Overall recovery from the Reverse Osmosis unit is controlled by a stainless steel concentrate throtting valve.
2.3.4 Wet panel
A "Wet" panel is provided for mounting of pressure instruments. A high pressure gauge & a low pressure gauge are provided on the wet panel with a 5-way & a 3-way valve. By operating the valve, the operator can note the feed pressure to various stages and the concentrate pressure. From these, stagewise pressure drop can be calculated. Stainless steel sample valves are also provided to collect samples from the various stages and final concentrate.
2.3.5 Electrical control panel The electrical control panel has a sheet steel enclosure and houses the controls and instruments for operation of the RO unit. Relay/timer based controls are provided for starting and stopping of the RO unit and for the safety of the high pressure pump.
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Please see the Technical Data Sheet for details of instruments provided.
3. T
ECHN
ICA
L DA
TA
3.1
Mic
ron
Car
tridg
e Fi
lter
25m
3 /hr
1
Ø50
0 x
600
HOS
SS31
6
PP S
pira
l W
ound
5 m
icro
ns
20m
3 /hr
1
Ø50
0 x
600
HOS
SS31
6
PP S
pira
l W
ound
5 m
icro
ns
15m
3 /hr
1
ø400
x
600
HOS
SS31
6
PP S
pira
l W
ound
5 m
icro
ns
12m
3 /hr
2
Jum
bo
20”
Lon
g
PP
PP S
pira
l W
ound
5 m
icro
ns
10m
3 /hr
2
Jum
bo
20”
Lon
g
PP
PP S
pira
l W
ound
5 m
icro
ns
8m3 /
hr
2
Jum
bo
20”
Lon
g
PP
PP S
pira
l W
ound
5 m
icro
ns
5m3 /
hr
1
Jum
bo
20”
Lon
g
PP
PP S
pira
l W
ound
5 m
icro
ns
4m3 /
hr
1
Jum
bo
20”
Lon
g
PP
PP S
pira
l W
ound
5 m
icro
ns
No.
off
Size
MO
C
Filte
r El
emen
t/
T ype
Ra
ting
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3.2
Hig
h Pr
essu
re P
ump
25m
3 /hr
1
37.0
18.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
30.0
2900
Gru
ndfo
s/
Equi
vale
nt
20m
3 /hr
1
30.0
17.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
22.0
2900
Gru
ndfo
s/
Equi
vale
nt
15m
3 /hr
1
21.5
16.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
15.0
290
0
Gru
ndfo
s/
Equi
vale
nt
12m
3 /hr
1
17.5
18.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
15.0
2900
Gru
ndfo
s/
Equi
vale
nt
10m
3 /hr
1
14.5
17.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
11.0
2900
Gru
ndfo
s/
Equi
vale
nt
8m3 /
hr
1
11.5
18.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
11.0
2900
Gru
ndfo
s/
Equi
vale
nt
5m3 /
hr
1 7.5
17.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
7.5
2900
Gru
ndfo
s/
Equi
vale
nt
4m3 /
hr
1 6.0
18.0
Gru
ndfo
s/
Equi
vale
nt
SS31
6
7.5
2900
Gru
ndfo
s/
Equi
vale
nt
No.
off
Cap
acity
(m
3 /hr
)
Head
(k
g /
cm2 )
Mak
e
MO
C
Mot
or ra
ting
(kw
)
Mot
or s
peed
(rp
m)
Mot
or M
ake
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3.3
Rev
erse
Osm
osis
Mod
ule
25m
3 /hr
RO
85-
320
3 : 2
II 2
250
PSI
GLO
BAL
CO
MPO
SITE
S /
EQUI
VA
LEN
T
8 5
TM 7
20 -
370
10
25.0
I 3 8 5 15
20m
3 /hr
RO
85-
211
2 : 1
: 1
III
1
250
PSI 8 5 5
20.0
II 1 8 5 5
I 2 8 5 10
15m
3 /hr
RO
85-
210
2 : 1
II 1
250
PSI 8 5 5
15.0
I 2 8 5 10
12m
3 /hr
RO
84-
210
2 : 1
II 1
250
PSI 8 4 4
12.0
I 2 8 4 8
10m
3 /hr
RO
85-
110
1 : 1
II 1
250
PSI 8 5 5
10.0
I 1 8 5 5
8m3 /
hr
RO 8
4-11
0 1
: 1 II 1
250
PSI 8 4 4
8.0
I 1 8 4 4
5m3 /
hr
RO 8
5-10
0 1
: 0
I 1
250
PSI
8 5 5
5.0
4m3 /
hr
RO 8
4-10
0 1
: 0
I 1
250
PSI
8
4 4
4.0
Mod
el
Arra
y St
age
Num
ber o
f pre
ssur
e tu
bes
Pres
sure
tube
ratin
g M
ake
of p
ress
ure
tube
Si
ze o
f pre
ssur
e tu
bes
(inch
) El
emen
ts/p
ress
ure
tube
El
emen
t mod
el
Num
ber o
f ele
men
ts
Max
imum
feed
flow
(m
3 /hr
) M
axim
um p
erm
eate
flo
w (m
3 /hr
) M
axim
um re
ject
flow
(m
3 /hr
) Re
ject
recy
cle
flow
(m
3 /hr
) %
reco
very
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Note: If Cleaning System is present, please refer to appropriate model for details.
3.4 Cleaning System
Model CS40 CS90
No. off 1 1
3.5.1 Tank
Size 500 lts 1000 lts
MOC HDPE HDPE
3.5.2 Pump
No off 1 1
Capacity m3/hr 9.1 20.4
Head mwc 30 30
MOC SS316 SS316
Motor rating HP 3.75 5.0
Motor speed RPM 2890 2900
3.5.3 Cartridge Filter
No off 1 2
MOC PP PP
Cartridge 10-micron, 20" Long 10-micron, 20" Long
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3.5 Instrument List
3.5.1 Pressure gauge No. off 1 Type Bourdon with Glycerine filled Range kg/cm2 0 - 40 Dial size mm 150 Make FGB/Eqvt. Location RO wet panel
3.5.2 Pressure gauge No. off 1 Type Bourdon with Glycerine filled Range kg/cm2 0 - 7 Dial size mm 150 Make FGB/Eqvt. Location RO wet panel
3.5.3 Low Pressure switch No. off 1 Type Spring Actuated Make kg/cm2 Switzer / Aster/Eqvt. Range 0.4 - 4.0 - 1nos
Location Ro Feed 3.5.4 High Pressure Switch No. off 1 Type Spring Actuated Make Switzer / Aster/Eqvt.
Range 8-32 kg/cm2 – 1nos Location High pressure pump delivery
3.5.5 Conductivity Indicator (For 200 Series RO) No. off 1 Model DM 50 Type Digital Indicator
Location RO Permeate Outlet Make Ion Exchange (India) Ltd.
3.5.6 Conductivity Indicator Alarm (For 300 Series RO) No. off 1 Model CON-5000 Type Digital Indicator / Transmitter
Location RO Permeate Outlet Make Ion Exchange (India) Ltd.
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3.5.7 ORP Analyzer (Optional) No. off 1 Type Digital-Online
Location RO inlet Model ORP 4000 Make Ion Exchange (India) Ltd.
4. INSTALLATION 4.1 INDUSTRIAL REVERSE OSMOSIS UNIT & CLEANING SYSTEM
1. Please refer to the Foundation Drawings. The RO unit needs a flat/hard surface in a closed area. Check the constructed foundations with the drawings.
2. Carefully unpack the equipment received and check for damages. Bring the equipment close to the place of installation. 3. Insert the foundation bolts in the pockets provided and install the frame for the RO unit. Level the frame by using metal shims and check the level with a spirit level. Fit washers and nuts onto the foundation bolts. Fill the foundation pockets with grout. After the grout has set, tighten the bolts evenly. 4. Fix the various items of equipment separately and tighten the foundation bolts and nuts. Complete the piping as per the drawing. 5. Complete the electrical wiring as per the Wiring Diagram. Inspect the electric control panel. 6. Ensure that the voltage supplied to the RO unit is as per the voltage identification tag. 7. Decouple the driven equipment from the motor. Check and correct the phase
sequence for the 3 phase motors by kickstarting the same. The rotation of the driven equipment such as the high pressure pump should be as per the arrow on the equipment. If found satisfactory, couple the motor with the drive.
Unauthorised persons should not attend to 3 phase/415 Volts power circuits. Running of high pressure pump in reverse direction can cause severe damage.
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5. OPERATION
5.1 INDUSTRIAL REVERSE OSMOSIS UNIT & CLEANING SYSTEM
Precommissioning, Membrane Loading
Initial Start-up, Initial Flushing
This section details the various steps involved in the precommissioning and initial startup of the RO unit. It also gives details of the operations involved in “Normal” starting and stopping of the unit.
5.2 Precommissioning
After completing installation activities including electrical wiring and before initial start up, a number of precommissioning activities need to be carried out. 1. Check and ensure upstream pumps and units are in proper operating condition. 2. Do not load the cartridge filter elements. Close the cartridge filter vessel cover. Without
starting the high pressure pump, flush the RO system with pretreated water. 3. Separately check the running of all dosing pumps, all instruments. 4. Dry check the operation sequence by electrically simulating various conditions. 5. Clean the RO pressure tubes and associated piping with a jet of water. 6. Check and ensure correct direction of rotation of the high pressure pump. 7. Check and confirm that feed water to RO will meet all limiting conditions. 8. Stop the pumps, close all valves, switch off the main electrical supply for membrane
loading. 5.3 Membrane Loading 1. Remove the victaulic connections from both ends of the pressure tubes. 2. Remove the allen screws. Carefully tap the end cap with a rubber mallet to relieve the
tension from the retaining rings. Then remove the rings one by one. 3. Put distinguishing marks on the end caps and respective tube ends (for ease of
reassembly). By using an even pulling force and ensuring that no damage occurs to any fittings, remove the end caps.
4. Remove the required number of membrane elements from the packing. Note down
the serial number of each membrane element and enter the same on the membrane loading chart (see Table 5.10) as the membrane element is loaded.
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5. Apply a liberal coat of silicone grease on the membrane `O’ ring and seals. 6. Insert the membrane elements into the pressure tube from the feed end (i.e. where the
piping from high pressure pump enters the RO unit). Membrane should enter so that the seals are near the feed end of the pressure tube.
7. If the pressure tube has more than one element, make the next membrane element
ready. Fix the interconnector on the leading end and join the same with the element which was already inside the pressure tube. Now push the new element so that the element inserted earlier goes in fully.
8. On the product end of the pressure tube, fix the product adaptors using silicone
grease. 9. Reinstall the end caps carefully and refix the rings and allen screws.
5.4 Initial start up 1. Open the cover of the cartridge filter vessel. Fix the filter elements and close the cover
lightly. 2. Check the quality of the feed water, particularly pH, temperature, chlorine, hardness,
conductivity and silt density index (SDI) to ensure that the parameters are not worse than the design water analysis given in Technical Data sheet.
3. Open reject control valve fully. 4. Open the high pressure pump discharge valve fully. 5. Remove the drain on the product header and connect a hose pipe to drain. This will
ensure that the product water during initial start-up and initial flushing does not contaminate the product water tank.
6. Open the manual feed water isolation valve to allow water flow into the RO system.
The cartridge filter will show a positive pressure and water will flow intothe drain near the reject outlet.
7. Continue this operation for 15 minutes to expel all air pockets in the system. Remove
the air from the high pressure pump casing by opening the vent.
5.5 Initial flushing The purpose of initial flushing is to remove the preservatives from the membranes and antifreeze chemicals applied on them at the time of shipping.
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Continuing after initial start-up, 1. Remove the lock out tag from the electrical control panel main ON/OFF switch and
switch on the power supply. 2. Close the high pressure pump discharge valve fully and reopen it to be ¼ open. 3. When the high pressure pump starts, slowly open the pump discharge valve to
increase the pressure and obtain and note the product flow. Close the reject control valve slowly and note the reject flow. As the reject control valve is closed, the permeate flow will increase. Simultaneously and carefully control both these valves to obtain product and reject flow rates as per the Technical Data sheet.
4. Start the dosing pumps (if present) and maintain the required dosage for the various
chemicals. 5. Continue for at least 2 hours, and keep observing the operating pressure and flow
rates. As the membrane gets conditioned, there will be some initial changes in these parameters, but they will soon stabilise.
6. Start operation of the various instruments provided on the panel. 7. Refix the drain plug on the product header.
5.6 Normal starting
In general, the operation of a reverse osmosis plant is fairly simple, the operator needs to ensure that The pretreatment plant is operating satisfactorily Necessary chemicals are available There are no leaks in the high pressure piping Various important parameters are entered in the log sheet. 1. Ensure that the manual feed water isolation valve is fully open. 2. Turn the main switch to ‘ON’ position. 3. Ensure that the high pressure pump discharge valve is open at least ¼. 4. Ensure that the reject control valve is partly open.
(CAUTION: A COMPLETELY CLOSED REJECT CONTROL VALVE CAN CAUSE SEVERE MEMBRANE DAMAGE.)
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5. Ensure that all valves downstream of the product water header (e.g. inlet to product water storage or inlet to degasser tower) are fully open.
6. Adjust the pump discharge valve and the reject control valves as described in point 3
& 4 of 5.4 so as to maintain the desired operating pressure, product and reject flow rates. Note the treated water quality parameters.
7. Adjust the reject control valve and the high pressure pump discharge valve to
maintain the treated water quality within acceptable limits. The operating pressure will rise slightly compared to the previous step.
5.7 Normal Shutdown
When the reverse osmosis unit needs to be shutdown for brief periods( less than 7 days), follow the procedure below: 1. Switch off the high pressure pump. 2. Switch off upstream units and pumps including dosing systems.
5.8 Long Term Shutdown
When the reverse osmosis unit needs to be shutdown for periods exceeding 7 days, use the following procedure: 1. Carry out a "Normal” shutdown as per the procedure given in 5.7 above. 2. Refer to 7.3 on disinfection and storage of Reverse osmosis membranes.
Note 1. Under the "Remarks" column record any routine activity like cleaning as well as any
malfunction of instruments, control panel etc. 2. Record any change in raw water source. 3. Measure and record the SDI value of feed water once a week. 4. A detailed raw water analysis should be done once in three months or whenever the
raw water conductivity changes by more than 10%. 5. Raw water analsysis should ensure the calcium, magnesium, sulphate, chlorides, silica,
cod, iron, pH, turbidity and TDS. 6. A change of more than 10% in the product flow or feed pressure or the product
conductivity should be reported immediately. Feed water to the reverse osmosis unit should be within following parameters:
Turbidity Less than 1 NTU Oil and Grease Nil SDI Less than 4 Organics Nil Temperature Less than 400C
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Table 5.10
RO Membrane Loading Chart
Note:
Use the blocks above to enter membrane Serial numbers. Mark the feed and the reject end for every tube. Enter various tubes as PT1, PT2 etc. (PT stands for pressure tube) Membrane Model :
Date of Installation :
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6. MAINTENANCE INDUSTRIAL REVERSE OSMOSIS UNIT & CLEANING SYSTEM
This section describes in detail mechanical maintenance aspects. There is an extensive discussion regarding the various foulants affecting the RO membranes and regarding membrane cleaning.
6.1 Mechanical Maintenance
Regular maintenance of Reverse Osmosis unit is required for a long troublefree performance. It will also enable the operator to pinpoint the causes of defective performance quickly. In general, since the Reverse Osmosis unit involves high pressure, it is necessary to ensure that there are no leaks and to attend to them immediately should they occur. It is also necessary to keep an inventory of essential spare parts so that problems can be attended to as soon as they occur.
6.1.1 Change of filter cartridges (Normally done when the pressure drop across the filter exceeds 1 kg/cm2) 1. Turn the RO unit main switch to ‘OFF’ position. 2. After ensuring that the pressure in the cartridge filter pressure gauge is zero, open the
cartridge filter cover and unscrew the nuts holding the cartridge filter elements. Remove the existing cartridge filter elements and discard them.
3. Observe the particulates to see if there is any abnormal carryover of sand, or activated
carbon or any other material. 4. Drain the cartridge filter body and wash it with water. 5. Install new cartridges/filter elements and refix the covers tightening the bolts evenly. 6. Turn the main switch to AUTO and restart operations.
6.1.2 Lubrication of high pressure pump 1. Turn the main switch to ‘OFF’ position. 2. Insert two strokes of lubricant from the hand operated becoming lubricant pump into
the grease filling near the motor end of the pump. 3. Turn the main switch to ‘AUTO’ position.
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6.1.3 Maintenance schedule
Sr. No.
Activity
Frequency
1
Inspect and attend leaks
Daily
2
Change filter cartridges
Once in 3 months or when the pressure drop > 1.0 kg/cm2 whichever is earlier
3
Lubrication of high pressure pump
Once in 6 months
4
RO membrane cleaning
See Note 1 below.
5
RO membrane replacement
See Note 2 below.
6
Instrument calibration
Refer instrument manuals.
Note 1 When the "normalised" productivity rate is more than 15% below that for clean
membrane, or When the RO feed pressure is 2.00 kg/cm2 higher than that with clean membrane.
Note 2 When after repeated cleaning performance is not restored to the desired extent.
6.2 Membrane Cleaning
This section provides general information about the usual foulants affecting the performance of Composite Polyamide Reverse Osmosis (RO) membrane elements and the removal of these foulants. The information in this section applies to 4 – inch and 8 – inch diameter RO membrane elements.
Note The Composite Polyamide type of RO membrane elements may not be exposed to chlorinated water under any circumstances. Any such exposures will cause irreparable
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damage to the membranes. Absolute care must be taken following any disinfection of piping or equipment or the preparation of cleaning or storage solutions to ensure that NO trace of chlorine is present in feed water to the RO membrane elements. If there is any doubt about the presence of chlorine, perform chemical testing to make sure. Neutralise any chlorine residual with sodium bisulphite solution, and ensure adequate contact time to accomplish complete dechlorination. It is recommended that all RO membrane cleaning operations should be closely co-ordinated with Ion Exchange (I) Ltd., during RO membrane element warranty period. IEI Ltd field service personnel should be on site, at least for the first cleaning event. The use of cationic surfactant should be avoided in cleaning solutions, as irreversible fouling of the membrane elements may occur.
6.2.1 RO membrane element foulants During normal operation over a period of time, RO membrane elements are subject to fouling by suspended or sparingly soluble materials that may be present in the feed water. Common examples of such foulants are calcium carbonates scale, calcium sulphates scale, metal oxides scale, silica coating and organic or biological deposits. The nature and rapidity of fouling depends on the condition of the feed water. Fouling is progressive, and, if not controlled early, will impair the RO membrane element performance in a relatively short time. Monitoring overall plant performance on a regular basis is an essential step in recognising when membrane elements are becoming fouled. Performance is affected progressively and in varying degrees, depending on the nature of the foulants. Table 7.1 provides a summary of the expected effects that common foulants have on performance of the RO system. 6.2.2 Foulant removal Foulant removal is achieved by cleaning and flushing. Further fouling is avoided by changing the operating conditions. As a general guide, foulant removal is required when any of the following conditions occur: 1. Permeate flow has dropped to 10-15 percent below rated flow at normal pressure. 2. Temperature corrected feedwater pressure has increased 10-15 percent to maintain
rated product water flow. 3. Product water quality has decreased 10-15 percent, salt passage has increased 10-15
percent. 4. Applied pressure has increased about 10-15 percent. 5. The differential pressure across RO stage has increased noticeably (instrumentation
may not be available to monitor this indication).
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The following paragraphs provide a discussion of the common foulants and their removal:
Calcium carbonate scale Calcium carbonate may be deposited from almost any feed water if there is a failure in the inhibitor addition or in the acid injection of pH control system that results in a high feed water pH. An early detection of the resulting calcium carbonate scaling is absolutely essential to prevent the damage that crystals can cause on the active membrane layers. Calcium carbonate scale that has been detected early can be removed by lowering the feed water pH to between 3.0 and 5.0 for one or two hours. Longer resident accumulations of calcium carbonate scale can be removed by recirculating a citric acid solution of 2 – percent strength and a pH of no less than 4.0 through the RO membrane elements. Ensure that the pH in any cleaning solution does not fall below 4.0 otherwise, damage to the RO membrane elements may occur, particularly at elevated temperatures. The maximum pH should be less than 10.0. Use sodium hydroxide to raise the pH, or sulphuric or hydrochloric acid to lower it.
Calcium sulphate scale Solution 2 is the best choice for removal of calcium sulphate scale from the RO membrane.
Metal oxides scale Precipitated hydroxides (e.g., ferric hydroxide) can usually be removed by using the techniques described above for calcium carbonate scale.
Silica scale A silica coating not associated with either metal hydroxides or organic matter will usually respond only to very specialised cleaning methods. Contact Ion Exchange (I) Ltd., for instructions related to a specific problem. Organic deposits Organic deposits (e.g. microbiological slimes and moulds) are best removed by using solution 3. To inhibit additional growth, recirculate and soak the membranes with a IEI Ltd’s approved biocide solution. This requires extended exposures to be effective; a biocide solution is best employed when an RO block or train is to be left in a standby condition for more than three days. Contact Ion Exchange (I) Ltd., for the biocide best suited for specific conditions.
Cleaning solutions The following chemical solutions are recommended for cleaning the RO membrane elements. The appropriate solutions to use can be determined by chemical analysis of the fouling material. A detailed examination of the results of the analysis will provide additional clues as to the best method of cleaning. Keeping records of the methods used and results obtained will provide data useful in developing the methods and solutions that work best under the feed water conditions at hand.
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Solution 1 is recommended for inorganic fouling. Solution 2 is recommended for calcium sulphate and organics. Solution 3 is recommended for high organic fouling. All solutions are to be used the highest available temperature up to 400C or upto 60 minutes of cleaning. The quantities given are as per 100 litres of water. Prepare the solutions by proportioning the amount of chemicals to the amount of cleaning water to be used. Use chlorine–free permeate to mix the solutions. Mix thoroughly. If additional information is needed, please contact Ion Exchange (I) Ltd.
RO membrane element cleaning and flushing The RO membrane elements in place in the pressure tubes are cleaned by recirculating the cleaning solution across the high pressure side of the membrane at low pressure and relatively high flow. A cleaning unit is needed to do this. The general procedure for cleaning the RO membrane is as follows: 1. Flush the pressure tubes by pumping clean, chlorine–free product water from the
cleaning tank (or equivalent source) through the pressure tubes to drain for several minutes.
2. Mix a fresh batch of the selected cleaning solution in the cleaning tank, using clean
product water. 3. Circulate the cleaning solution through the pressure tubes for approximately one hour
or the desired period of time, at a flow rate of 133 to 151 l / min per pressure tube for 8.0 and 8.5 – inch pressure tubes, or 34 to 38 l / min for 4.0 – inch pressure tubes.
4. After completion of cleaning, drain and flush the cleaning tank; fill the cleaning tank
with clean product water of the same pH as that of cleaning solution for rinsing. This is done to avoid precipitation of the matter which was dissolved during cleaning.
5. Repeat above step with permeate at neutral pH. 6. After the RO system is rinsed, operate it with the product dump valve open until the
product water flows clean and is free of any foam or residues of cleaning agents (usually 15 to 30 minutes).
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Table 6.2.3
RO Membrane Element Foulant Symptoms
Foulant General Symptoms Response 1.Calcium precipitates (carbonates and phosphates, generally found at the concentrate end of the system.
A marked decrease in salt rejection and a moderate increase in pressure between feed and concentrate. Also a slight decrease in system production.
Chemically clean the system with solution 1.
2. Hydrated oxides (iron, nickel, copper etc)
A rapid decrease in salt rejection and a rapid increase in pressure between feed and concentrate. Also a rapid decrease in system production.
Chemically clean the system with solution 1.
3. Mixed colloids (iron, organic and silicates)
A slight decrease in salt rejection and a gradual increase in pressure between feed and concentrate. Also a gradual decrease over several weeks in system production.
Chemically clean the system with solution 2.
4. Calcium sulphates (generally found at the concentrate end of the system)
A significant decrease in salt rejection and a moderate increase in pressure between feed and concentrate. Also a slight decrease in system production.
Chemically clean the system with solution 2.
5. Organic deposits Possible decrease in salt rejection and a gradual increase in pressure between feed and concentrate. Also a gradual decrease in system production.
Chemically clean the system with solution 2. For heavy fouling, use Solution 3.
6. Bacterial fouling Possible decrease in salt rejection and a gradual increase in pressure between feed and concentrate. Also a gradual decrease in system production.
Chemically clean the system with either of the solutions, depending on possible compound fouling.
The detailed trouble shooting guidelines and suggested treatment are attached herewith to be followed .All problems require the cause of the fouling to be corrected. Contact Ion Exchange (I) Ltd., for assistance.
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Table 6.2.4
Summary of Recommended Cleaning Solutions
Solution Ingredients Quantity pH adjustment
1 Citric Acid RO product water (chlorine free)
1.0 Kg 100 litres
Adjust to 4.0 with sodium hydroxide (NaOH)
2
Sodium tripolyphosphate Tetra sodium EDTA RO product water (chlorine free)
2.0 kg 0.84 kg 100 litres
Adjust to 10.0 with sulphuric acid (H2SO4)
3
Sodium tripolyphosphate Sodium Dodecylbenzene RO product water (chlorine free)
2.0 kg 0.26 kg 100 litres
Adjust to pH 10.0 with sulphuric acid (H2SO4)
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INSTRUCTIONS FOR RO PLANT SERVICING / MEMBRANE CLEANING
1) Collect the details of particulars of client like previous field service report, contact
person, address etc. 2) Discuss and review the operation of the plant with contact person/operator. Note
down the problems if any. 3) Refer the logbook for product flow, reject flow, water quality and system pressure. 4) Check the pre-treatment and confirm the system is working as per
design/requirements. 5) Identify the type of membrane. 6) Identify the plant problem from the trouble shooting guidelines. 7) Apply the appropriate treatment program as per guidelines . 8) Carry out the membrane cleaning. 9) Compare the product flow, reject flow, system pressure, treated water quantity.
Collect all the details and put it in the log sheet. 10) Prepare field service report giving details of job carried out, list out essential spares
required and the suggestions on plant monitoring and control. Propose the next servicing schedule and get it signed by the client. Forward the copy of the report to Branch in-charge/service in-charge.
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7. TROUBLE SHOOTING INDUSTRIAL REVERSE OSMOSIS UNIT & CLEANING SYSTEM
This section gives the symptoms, likely causes and corrective actions required for the RO unit. For smooth operation of the plant, continuous attention must be given to feed water quality, operating parameters and routine maintenance. Sr. No
Symptom
Likely cause
Consequences if not corrected
Corrective action
1.
Increase in SDI at CF outlet
Change in quality of raw water Coagulant / Flocculant dosing malfunction Channeling in the sand filter. Inferior quality of chemical. Inadequate backwash of filter
Fouling of membranes leading to reduction in product flow
Check raw water quality Check coagulant / Flocculant dosing system. Carry out fresh jar test if required. Check sand filter Use right quality of chemicals. Give sufficient backwash to the filters.
2.
High/Low pH
Acid level low / Blockage in acid line Feed water quality / flow change
Fouling of membranes Damage to the membranes
Refill acid / Check acid pump suction and discharge. Check feed water flow, adjust dosage as needed.
3.
Residual chlorine at Cartridge filter outlet
Change in quality of raw water. Maloperation of sodium
Damage to RO membranes (decrease in salt rejection)
Check raw water quality. Adjust dosing rate. Repair the pump.
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hypochlorite dosing pump. Change in raw water flow
Adjust raw water flow.
4.
Low pressure at H.P. pump suction
Raw water pump malfunction. Excessive pressure drop at MGF/CF Malfunction of auto feed water valve/solenoid valve.
H.P. pump may get damaged due to cavitation.
Check raw water pump. Give backwash to MGF, change cartridges. Recalibrate pressure gauge / pressure switch. Check solenoid valve/auto feed water valve.
5.
Auto feed water valve does not open.
Solenoid valve malfunction. Wrong installation of this valve.
RO unit will not function.
Check solenoid valve. Check installation of auto feed water valve.
6.
Increase in RO feed pressure
Increase in RO feed conductivity Fouling / Scaling of membranes Reject valve maloperation Pressure gauge malfunction
Lower product flow Lower membrane life
Check raw water quality / SDI Membrane cleaning. Adjust recovery Check pressure gauge.
Probing / profiling to find ‘O’ ring leakage / membrane damage. Replace damaged membranes / ‘O’ rings. Eliminate the cause of damage. Clean the membranes. Recalibrate product cond. indicator.
Membrane may damage HP pump may get damaged Leakage of joints / connectors
Check the valves Check fouling on membranes Any blocks / foreign particles water passage through pressure tubes / pipes
12.
ORP dump valve does not open
Solenoid valve malfunction. Wrong installation of this valve.
RO unit will not function.
Check solenoid valve. Check installation of auto feed water valve.
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CHAPTER 8
DEFINITIONS OF TERMS CONCENTRATE The portion of the feed stream which does not pass through the membrane. It contains retained dissolved or suspended materials at a concentration higher than that of the feed stream. Also known as “RETENTATE”. CONCENTRATION POLARISATION The condition which results when the retained dissolved materials become concentrated in the thin boundary layer adjacent to the membrane surface. The gel layer thus formed presents a barrier to fluid migration to the membrane and reduces overall flux. Proper design of cross flow filtration and cleaning techniques minimizes the effect. DIAFILTRATION The continuous exchange of process solution with fresh solvent, thereby removing membrane permeating species from the batch. ENDOTOXINS Generally refers to the lipopolysaccharides coming from the cell walls of dead bacteria. Frequently used interchangeably with pyrogen. FEED The influent stream to the ultrafiltration system, which is then split into a permeate stream and concentrate stream. FLOW DEPENDENT UF feed streams where fouling mechanisms must be controlled to allow predictable permeation rates through the membrane. FLUX Rates at which fluid permeates or flow through the membrane, usually expressed in gallons per square foot of membrane per day (GSFD).
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GEL LAYER A layer of highly concentrated or precipitated solids, usually of high molecular weight species, adjacent to the active surface of an operating ultrafiltration membrane. The gel layer permeability rather than membrane permeability often controls ultrafiltration flux. HUMIC ACID Any of various organic acids that are insoluble in alcohol and organic solvents and are obtained from humus. HUMUS A brown or black complex and varying material formed by the partial decomposition of vegetable or animal matter the organic portion of soil. LAL Limulus Amebocyte Lysate is a chemical, which is sensitive to the presence of pyrogenic material (endotoxin). The LAL test measures the concentration of pyrogens which is reported as endotoxin units (EU’s) in a specified volume. MEMBRANE ANISOTROPIC A synthetic polymeric membrane composed of a very tight thin skin on one side supported by a sponge like layer. The skin or active membrane, functions as the semi-permeable barrier to solute flow causing rejection of macromolecules in solution and any colloidal or suspended material. MOLECULAR WEIGHT CUTOFF The membrane specification describing the normal rejection of a known molecular species dissolved or suspended in the feed stream. PERCENT RECOVERY Ration of permeate flow to feed flow PERMEATE Portion of the feed stream, which passes through the membrane, essentially free of colloidal, particulate and microbiological species.
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POINT-OF-USE SYSTEM A filtration system which is installed very near to the location where the water is consumed. this is in contrast to a central water system or loop, which is generally, located a considerable distance from the point where the water is used. POLYETHERSULFONE An engineering thermoplastic polymer from which ultrafiltration membranes having desirable properties of toughness, chemical resistance and thermal stability can be formed. PPB Parts Per Billion, refers to the concentrations by weight of a material relative to fluid in which it is placed. PRESSURE DEPENDENT UF feed streams where fouling or concentration polarization is relatively unimportant. PYROGEN Any substance, which causes a temperature rise when, injected. A common source is bacteria fragments. See endotoxin. RECOVERY RATE The amount of fluid (permeate) collected which has passed through the membrane expressed as a percent of the feed stream. REJECTION RATE One (1) minus the ratio of a specific solute concentration in the permeate to the concentration of the solute in the feed expressed as a percentage. RETENTATE See CONCENTRATE, Reject from Ultrafiltration System, REVERSE OSMOSIS By application of pressure (above osmotic pressure) on a salt solution against a semi-permeable membrane, pure water is forced through the membrane leaving behind salts. SOLUTE REJECTION A measure of the ability of the ultrafilter to block the passage of material dissolved or suspended in the feed stream.
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SOLUTE The constituents of a solution which are dissolved in the solvent. TIC Total Inorganic Carbon is similar to TOC but measures inorganic carbon. TOC Total Organic Carbon or Total Oxidizable Carbon measures the total organic material by high temperature oxidation or carbon dioxide. Detects presence of organic material down to parts per billion. ULTRAFILTRATION A membrane separation process similar to reverse osmosis in which relatively higher molecular weight materials are separated from a feed stream. 18 MEG-OHM WATER Water which has been treated to remove conductive materials. For pure water, the theoretical value for resistivity is 18 meg-ohm at 25 deg. C.
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INDION Easy Test Kit We recommend use of INDION REVERSE OSMOSIS (RO) MX TEST KIT for quick measurement of key parameters like pH, Hardness, Free Chlorine, Iron, Silica and Fluoride.