Issued in June 2009
Revised in March 2014

TORAY Submerged UF
MEMBRANE ELEMENT
Instruction Manual
Model:
HSU-1515

issued by

Toray Industries, Inc.

Water Treatment & Environment Division
2-1-1, Nihonbashi-Muromachi, Chuo-ku, Tokyo 103-8666 Japan
Tel: +81-3-3245-4557
Fax: +81-3-3245-4913
URL: http://www.toray.com
BJADJCAG

ContentI.

Introduction ...................................................................................................... 1
1. Characteristics of Toray Submerged UF Membrane Rack ............................... 1
2. Applications of Toray Submerged UF Membrane Rack .................................... 2II.

For Your Safety ................................................................................................ 3
1. Safety Instruction for Unpacking and Installation ............................................. 4
2. Safety Instruction for Filtration Operation ........................................................ 6
3. Safety Instruction for Chemical Cleaning ......................................................... 8
4. Safety Instruction for Disposal ......................................................................... 9III. Outline ........................................................................................................... 10
1. Outline of membrane ..................................................................................... 10
2. Outline of element ......................................................................................... 11
3. Outline of rack ............................................................................................... 12
IV. Specifications and Configuration .................................................................... 13
1. Specifications of Membrane .......................................................................... 13
2. Specifications and Configuration of Element ................................................. 14
3. Specifications and Configuration of Rack ...................................................... 16
4. Feed water and Cleaning Limits .................................................................... 20
V.

Installation ..................................................................................................... 21

VI. Operation ....................................................................................................... 25
1. Advance preparation ..................................................................................... 25
2. Filtration ........................................................................................................ 27
3. Backwash and Air-scrubbing ......................................................................... 29
4. Toray Maintenance Cleaning ......................................................................... 31
5. Air Diffuser Cleaning...................................................................................... 32
6. Temperature Correction Factor ...................................................................... 34
VII. Integrity Test and Maintenance ...................................................................... 35
1. Pressure Decay Test (PDT) ........................................................................... 35
VIII. Maintenance .................................................................................................. 38
IX. Storage of New Element and Rack after use.................................................. 42
1. Storage of New Membrane Element .............................................................. 42
2. Storage of Rack after use .............................................................................. 42

I.

Introduction

Toray Submerged UF Hollow Fiber Membrane Rack is the submerged type hollow
fiber UF (ultra filtration) membrane rack developed with the polymer science andthe membrane fabrication technologies accumulated for a long time in Toray
Industries, Inc.
The membrane material is Polyvinylidene fluoride (PVDF). The nominal molecularweight cut off of the membrane is 150,000 daltons. It has been confirmed that morethan 90% of 150,000 daltons model polymers is consistently removed.
The element, with Polyethylene (PE) protective cylinder, is submerged type. The
maximum operating trans-membrane pressure is 100 kPa (14.5 PSI). The flow
direction is outside to inside which is suitable for high turbidity water treatment
because the air-scrubbing can be adopted to remove suspended solid effectively.

1. Characteristics of Toray Submerged UF Membrane Rack
(1) High Filtration Flux
It provides high filtration flux and stable operation for the filtration of various
raw water sources. The membrane is made with a special spinning method,which enables high permeability and high fouling resistance.
(2) Excellent Water Quality
It provides very good water quality for the filtrate, extremely low turbidity since
the membrane has 150,000 dalton nominal molecular weight cut off. The rack is
recommended to be applied in high turbidity water treatment, such as for
tertiary treatment of sewage water and industrial waste water reuse.
(3) High Mechanical Strength
The membrane has very high mechanical strength because it is made of PVDF
with the special spinning method developed by Toray. The rack provides highintegrity and durability under recommended operating conditions.

1(4) High Chemical Durability
The membrane material is PVDF, which allows you to clean the membrane withhigh concentrations of chlorine and with high concentrations of acid resulting in
better cleaning and longer sustainable membrane flux rates.

2. Applications of Toray Submerged UF Membrane Rack-

Drinking Water Production
Membrane Elements certified with NSF61-

Tertiary Treatment of Sewage Water-

Industrial Water Production-

Reuse of Industrial Waste Water

2

II.

For Your Safety-

Please be sure to read and follow the instructions below before using. Thismanual should be retained for future reference.

-

Follow the safety precautions as they are intended to protect operators andequipment from various risks such as physical harm and/or property
damage. The following table shows a level of potential risk for eachindicated symbol.

! DANGERThis symbol indicates an imminent hazardous situation
which will result in serious injury or death when the
instruction is not observed.

! WARNING

This symbol indicates a potentially hazardous situation
which will result in serious injury or death when the
instruction is not observed.

! CAUTION

This symbol indicates a potentially hazardous situation
which might result in injury or property damage when
the instruction is not observed.

-

The following table explains the information to be noted.
“Prohibited”
This symbol indicates a prohibited action or procedure.
Prohibited!!

Instruction“Instruction”
This symbol indicates an important action or procedure
which has to be taken without fail.

3

1. Safety Instruction for Unpacking and Installation! DANGER!!

Instruction

Be sure to wear safety gear such as rubber gloves and safety glasses
for unpacking. The membrane is packaged in sodium hypochlorite
solution (100mg/L). If the solution happens to touch on the skin, wash
the affected part with running water. If the solution happens to get in theeyes or mouth, wash the affected part with sufficient amounts of clean
running water for more than 15 minutes and see the doctor immediately.

!!

When lifting rack, please attach chains or slings to it and raise it straight!!

When installing rack, please set up a foothold in advance. Please neverInstruction

Instruction

upward calmly to prevent it from shaking. Please never allow any
person under lifted article.

do the work above the rack. Use protective equipment to ensure thesafety of workers.

! WARNING!!

Be sure to wear safety gear such as a helmet and safety shoes to avoid
injury.

Instruction! CAUTION
The preservative solution should be washed out before using theelement. After that, keep clean water on the element to prevent theProhibited

membranes from drying out (for example, sprinkle on the element withwater). Do not allow the element to dry even for a few hours.
The element should not be frozen.

Prohibited4

Be careful not to damage or dent the element during handling.
Prohibited!!

Instruction

IDF/ISO Clamp Union Fittings 1.5 are applied for connecting theelement of HSU-1515 to the piping. Do not overtighten the cramp as
damage to the element may occur.
Keep the connection surface free of any dirt or oils.

Prohibited

Be sure not to install the element upside down. Confirm the element
Prohibited

!!
!!
!!

installed in the right direction.

Be sure to install the element vertically for effective air scrubbing.

Instruction

Be sure to store the element transversely.

Instruction

Instruction

At transportation, storage and installation rack, please take appropriate
measures to protect rack from damage.
Do not put any heavy objects on the rack. Please take care to protect
the rack from collision with other objects.

!!

Instruction

Please take adequate measures to protect rack from sparks caused bywelding, fusion cutting or grinding throughout the entire process frominstallation work to operation setup.

5

2. Safety Instruction for Filtration Operation! DANGER!!

Instruction

Flush all the piping out with clean water and make sure no debris isremaining in the piping prior to charging water to the element from thepiping.

!!

Confirm that the preservative chemical in the element and the piping is!!

Prior to use, make certain elements are washed. Filtrate water should

Instruction

completely washed out before starting the filtration operation. The
preservative chemical is harmful to humans.

be drained unless it meets the required quality.

Instruction! WARNING!!
!!

Protect elements from direct sunlight and ultraviolet light. Ultraviolet
light can degrade element housing and membranes.

Instruction

Instruction

Constantly monitor filtrate water quality such as turbidity and/or thenumber of particles during filtration, and stop the operation if abnormal
water quality is detected.
Do not exceed the maximum applicable trans-membrane pressure for
filtrating 100 kPa or for backwashing 200 kPa. Higher pressures can

Prohibited

damage the elements. Do not exceed the maximum temperature of 40
degree C . The higher temperature damages the elements.
Do not freeze the elements.

Prohibited6

!!

Instruction

The operating conditions, including the filtration flux and the periodical
physicalcleaning,

must

be

properly

set-upotherwisethetrans-membrane pressure may rise too quickly. The operation range is
described in the latter section of this manual.
Do not overfeed air to the element. Excessive scrubbing air damages!!

Instruction!!

Instruction

the membranes and/or shortens the membrane life.
The air flow rate should be within the range below for each element.
HSU-1515: 1.5 – 3.0 Nm3/h
At the Integrity tests, such as Pressure Decay Test (PDT) or Diffusive
Air Flow (DAF) Test, keep the air pressure below 125 kPa. Keep thesource air pressure lower than 200 kPa, to prevent the element
damaged.

7

3. Safety Instruction for Chemical Cleaning! DANGER!!

Instruction

Take special precautions when handling chemicals during chemicalcleaning. Wear the safety gear such as safety glasses and protective
gloves. If chemicals come in direct contact with your skin or your clothes,treat the contacted part appropriately based on the MSDS.
Do not mix sodium hypochlorite with acid. Such mixture generates toxic

Prohibited!!

chlorine gas.

Stop operation whenever any anomaly occurs with the equipment or
any signs of an anomaly are observed.

Instruction! CAUTION!!

Instruction

In the chemical cleaning, strictly follow the procedure described in thelatter section of this manual. Otherwise you may damage the elements
or negatively affect the membrane performance.

84. Safety Instruction for Disposal! WARNING!!

Instruction

When dispose the element, please apply a service of a qualified waste
disposing company. When the element is to be incinerated, pleaseapply the appropriate facilities in which hydrogen fluoride (HF) gas canbe neutralized. HF gas is generaterd with the incineration of membrane.

9III. Outline
1. Outline of membrane
The hollow fiber membrane installed in this rack is made of PVDF (Polyvinylidene
fluoride). Cross section of the structure is shown in Fig. 1. Flow direction to thehollow fiber membrane is outside to inside.

Flow Direction(Outside-in)

Cross Section

Fig. 1

Cross section picture of Toray PVDF hollow fiber

The diameter of the hollow fiber membrane is designed to be as follows:
For HSU-1515: Outside diameter is 1.4 mm. Inside diameter is 0.9 mm.
Molecular weight cut off (MWCO) of the HSU membrane is shown in Fig. 2. The
MWCO is determined by dextran solution having molecular weight of 70,000,
200,000 and 500,000. The concentrations of the dextran are measured by the
Refractive Index Detector.

Rejection (%)

100
80
60
40
20
0
10,000100,000

1,000,000

MW of Dextran

Fig. 2

Molecular weight cut off (MWCO) of the HSU membrane

10The membrane is manufactured with special spinning method developed by
TORAY and the nature of the membrane surface is modified for high fouling
resistance. As a result, this membrane enables very high filtration flux compared toother PVDF membranes. In addition, the physical strength of the membrane fiber isso high that it hardly gets breakage during the normal operation for many years.

2. Outline of element
TORAY PVDF Hollow Fiber Membrane Element “HSU-1515” is submerged typewhich is shown Fig. 3.
Effective membrane area of an element is as follows:
HSU-1515: 20 m2
HSU-1515: suitable for high turbidity water, large-scale water treatment plants.

Fig. 3

Picture of element (HSU-1515)

11

3. Outline of rack
“Rack” contains a number of membrane elements stacked at equal clearance andtwo air diffusers. Each element is connected to the permeated water manifold.
The air diffuser consists of a number of holes to supply scouring air to eachmembrane element.
This rack is used submerged in water to be treated.
Rack image is shown Fig. 4.

Air Drain

Feed

Permeate

Backwash
Drain
Fig. 4

Image of “Rack” (4 units of R16 Model are submerged in tank)12IV. Specifications and Configuration
1. Specifications of Membrane
Table 1.

Specifications of membrane *1)

Membrane TypeHSU

Nominal Molecular Weight Cut Off

150,000 *2)

Membrane material

PVDF

Filtrating
Trans-Membrane
Pressure
BackwashingTrans-Membrane
Pressure

Maximum *3)

100 kPa

Normal Operation

Not higher than 100 kPa

Maximum *4)

200 kPa

Normal Operation

Not higher than 150 kPa

Storage and Operating
Temperature Range

0 - 40 degree C

Operating pH Range

1 – 10*1): Please note that the specifications are subject to changes from time to time.
*2): The nominal molecular weight cut off is determined with the model test of dextran.
*3): TMP (Trans-Membrane Pressure) should be below 100 kPa at any time evenduring the filtration.
*4): TMP (Trans-Membrane Pressure) should be below 200 kPa at any time evenduring the backwash.

13

2. Specifications and Configuration of Element(1) Specifications of element
Table 2.

Specifications of element *1)

Element Type

HSU-1515

Membrane TypeHSU

Membrane Surface Area
(Outer Surface)

20 m2

Diameter

147 mmLength1,327 mm

Wet Condition

18 kg

Cap

ABS

Dimensions
WeightMaterials

Connections

OperatingConditions

Protective
CylinderPotting
MaterialPE
Epoxy or equivalent

Top Center

IDF/ISO Clamp Union Fitting 1.5s

Max. Feed
Water FlowMax.
BackwashFlow

2.0 m3/hMax. Air Flow

4.5 Nm3/h

Normal Air
Flow
Filtration
MethodMaximum
Temperature

1.5 – 3.0 Nm3/h

3.0 m3/h

Submerged, Outside to inside
40 degree C*1): Please note that the specifications are subject to changes from time to time.

14

(2)

Configuration of element

Filtrate Outlet

Inlet of Backwash Water
180(a)(a): Nozzle(b): Nut(b)

Lowest Water Level
in Filtration
Feed

Drain

Drain

Air

Air

1327

Feed

Connections
Pipe fitting
outerdiameter
mm
(a)

156

Feed

Drain
Air

Fig. 5

Configuration of element

1550Connectors
IDF/ISO Clamp
Union Fitting 1.5s

3. Specifications and Configuration of Rack
(1) Specifications of Rack
Table 3.

Specifications of Rack Module “R16“ *1)No. of Elements / Rack

16 elements

Element Type

HSU-1515

Total Membrane Area
(Outer Surface)

320 m2Height1,800 mm

Length

1,587 mmWidth

365 mm

Wet Condition

Max. 500 kg

Element

PVDF, ABS, PE,
Epoxy or equivalent

Rack

304SS *2)

Pipe304SS *2), PP, HIVP

Max. Feed
Water FlowMax.
BackwashFlow

32 m3/hDimensions

WeightMaterials

OperatingConditions

48 m3/hMax. Air Flow

72 Nm3/hNormal Air
Flow
Filtration
MethodMaximum
Temperature

24 – 48 Nm3/h
Submerged
Outside to inside
40 degree C*1): Please note that the specifications are subject to changes from time to time.

*2): 316SS is available as option.

16

Table 4.

Specifications of Rack Model “R08“ *1)No. of Elements / Rack

8 elements

Element Type

HSU-1515

Total Membrane Area
(Outer Surface)

160 m2Height1,800 mm

Length851 mmWidth

365 mm

Wet Condition

Max. 250 kg

Element

PVDF, ABS, PE,
Epoxy or equivalent

Rack

304SS *2)

Pipe

304 SS*2), PP, HIVP

Max. Feed
Water FlowMax.
BackwashFlow

16 m3/hDimensions

WeightMaterials

OperatingConditions

24 m3/hMax. Air Flow

36 Nm3/hNormal Air
Flow
Filtration
MethodMaximum
Temperature

12 – 24 Nm3/h
Submerged
Outside to inside
40 degree C*1): Please note that the specifications are subject to changes from time to time.

*2): 316SS is available as option.

17

(2) Configuration

Rack Model “R16”18

Rack Model “R08”19

4. Feed water and Cleaning Limits
Table 5.

Feed water limits *1)

Element Type

HSU-1515

Intermittent Peak *5)

1,000 NTU

Continuous Maximum

200 NTU

Intermittent Peak *5)

1,000 mg/L

Continuous Maximum

200 mg/L

Turbidity

TSS
Pretreatment Filter Mesh Size

Smaller than or equal to 0.5 mm

Temperature Range

0 - 40 degree C

pH Range

1 – 10*1): Please note that the specifications are subject to changes from time to time.
*5): The duration time should be less than 48 hours and the occurrence frequency
should not exceed more than once a month.

Table 6.

Cleaning limits for all types of elements*1)

Cleaning pH Range

0 – 12

Cleaning Temperature Range

0 - 40 degree C

Maximum Concentration of NaClO as Cl2

3,000 mg/L (10 < pH < 12)

Maximum NaClO Exposure(lifetime contact time) as Cl2

1,000,000 mg/L hours

Maximum Acid Contact Time

1,000 hours (pH > 0)*1): Please note that the specifications are subject to changes from time to time.

! CAUTION

Handle and operate the elements within the ranges
and the limits indicated in Table 1 to 6. Operation out ofthese ranges or limits may damage the elements, andaffect filtration performance.

20

V.

Installation

1. Element into Rack
(1)Unpack the wooden box. Take the element out of plastic bag.

! DANGER- Wear rubber gloves and safety glasses when you
unpack the element.

(2) Confirm the nozzle and the nut are not loose.

! WARNING- Do not drop the element.

! CAUTION- Be careful not to install the element upside down.
Confirm the element is installed in the right direction.
- Do not allow the element to dry even for a few hours,
especially in summer.
- Do not freeze the element.

(3) Set the element vertically into a rack (see Fig. 6). Make sure that the element isinstalled vertically. Please contact us if you need the detail information of therack.
(4) Connect a filtrate piping to a connection point of the element with a ferrule joint(see Fig. 6).

!

- Keep the connection surface free of any dirt or oils.

CAUTION- Do not over-tighten the clamp when using ferrule
joints (IDF/ISO Clamp Union Fittings 1.5s), or you
may damage the element.

(5) Immerse gradually the element rack in a submerged tank which filled raw water.

21

- Do not drop the element rack.

! WARNING- Use the equipments such as chain blocks, a crane ora forklift truck when you handle the element rack.

(6) Make sure that the element rack is installed vertically.

! CAUTION- If the element is not installed vertically, the effect of
the air scrubbing would be reduced and an effective
filtration will be impaired.

2
d
e

b

f

a : Elementb : Rack
c : Fixing Protrusiond : Ferrulee : Gasket
f : Clampa1c
1 : Element installing to a rack2 : Element connecting to a piping
Fig. 6

Installation of Element in Membrane Rack

22

2. Layout of Rack in Membrane Submerged Tank
Fig.7 and Fig.8 present a top view and a side view of the tank containing three
membrane racks. It is required to keep the dimensions of W1, W2, W3 and L1
as mentioned below.
Liquid Level
Union

L1

Manifold

Top of Manifold
Foothold

Guide

Guide
Rack

Tank Wall

W2

Fig. 7

W3

Rack Layout in Membrane Submerged Tank (side view)

Guide Rail

Guide
Rail

W1
Rack

P1
Foothold

Rack
P1
Rack

W4
W1
Tank Wall
Fig. 8

Rack Layout in Membrane Submerged Tank (top view)

23

(i)

P1: more than 424 mm(ii)

L1: L1, the distance between the top of the rack and the liquid
level of the tank, should be more than 100 mm at anytime of thenormal operation. (the maximum is when after finishing backwash,the value is changing depend on operation condition. Please contact
us for the details)(iii)

W1: more than 30 mm(iv)

W2: more than 30 mm(v)

W3: more than 30 mm(vi)

W4: more than 800 mm

24

VI. Operation
1. Advance preparation(1) Check that all piping is connected appropriately and flushed out prior to theoperation. Fig. 9 shows a typical example of piping.

V-1

Membrane
Rack

V-6

Feed
raw water
V-2

V-4
Filtratewater

Filtratepump

V-5
Air forscrubbingMembrane
Submerged
Tank

V-7 Backwash
pump

Backwashtank

Chemicaltank

Chemical feed
pump

V-3
Drainage

Fig. 9

Typical example of piping(2) Open the feed water valve (V-1) to provide the submerged tank with the feed
raw water. Make sure the water level of the submerged tank is higher than the
top of the filtrate piping.
(3) Open the filtrate water valve (V-2) and the air drain valve (V-6). Make sure thefiltrate piping between the filtrate pump and the membrane element is filled byfiltrated water.
(4) Close the air drain valve (V-6) and then run the filtrate pump. Make sure thewater in the backwash tank is enough for the next step, stop the filtrate pumpand close the feed water valve (V-1) and the filtrate water valve (V-2).
(5) Open the air drain valve (V-6) and the backwash valve (V-4) and run the
backwash pump until the filtrate piping is filled by filtrated water.
(6) Make sure all pumps are “stopped” and all valves are “closed”.

25

! CAUTION- The element is packaged in sodium hypochlorite
solution (100mg/L) as the preservative at the time of
shipment. The preservative should be washed out
before using the element. After that, keep cleanwater on the element to prevent the membranes
from drying out. Do not allow the element to dry evenfor a few hours.

26

2. Filtration
Fig. 10 shows a typical example of the flow diagram for filtration.
V-1

Membrane
Rack

V-6

Feed
raw water
V-2

V-4
Filtratepump

V-5
Air forscrubbingMembrane
Submerged
Tank

V-7

Filtratewater

Backwashtank

Backwashpump

Chemicaltank

Chemical feed
pump

V-3
Drainage

Fig. 10

Flow diagram for filtration(1) Open the feed water valve (V-1) to provide the submerged tank with the feed
raw water.
(2) Open the filtrate water valve (V-2) and run the filtrate pump. The flow rate of thefiltrate water is controlled either by a control valve (not shown in the figure) set
up after the filtrate pump on the filtrate line or by controlling the rotation speedof the filtrate pump.
(3) Make sure the filtrate water quantity is controlled.
(4) Make sure the water level of the submerged tank is higher than the Lowest
Water Level shown in Fig. 5 at any time in control of feed flow.

27

! CAUTION- Do not impose the higher pressure to the element
than

the

maximum

applicabletrans-membranepressure, for filtrating 100 kPa.
- Do not operate the element at higher temperaturethan the maximum applicable temperature, 40
degree C. The higher temperature damages theelement.
- Do not keep the element without water even for a
few hours.
- Operating conditions including the filtration flux andthe physical cleaning should be properly set up,
observing the rise of trans-membrane pressure(Details are described in the next session.). Pleasecontact us if you need technical support.

(5) When you stop the filtration, stop the filtrate pump and close the filtrate water
valve (V-2), and then close the feed water valve (V-1) after make sure waterlevel of the submerged tank is higher than the Lowest Water Level shown in Fig.
5.

! CAUTION- Always monitor filtrate water quality during filtration,and stop the operation if abnormal water quality isdetected. If abnormal water quality is detected,
check the integrity of the element with PDT(Pressure Decay Test) or DAF (Diffusive Air Flow)
Test. The test procedure is provided as the technicalinformation by Toray.

28

3. Backwash and Air-scrubbing
The physical cleaning with backwash and air-scrubbing should be carried out
periodically and automatically for the continuous filtration. The frequency of thephysical cleaning mainly depends on the raw water quality (Typical frequency isonce every 30 minutes normally. Please contact us if you need technical support.).
Fig. 11 shows a typical example of the flow diagram for backwash andair-scrubbing.
V-1

Membrane
Rack

V-6

Feed
raw water
V-2

V-4
Filtratepump

V-5
Air forscrubbingMembrane
Submerged
Tank

V-7

Backwashpump

Filtratewater

Backwashtank

Chemicaltank

Chemical feed
pump

V-3
Drainage

Fig. 11

Flow diagram for backwash and air-scrubbing(1) Close the feed water valve (V-1).
(2) Stop the filtrate pump and close the filtrate water valve (V-2) when the waterlevel of the submerged tank reaches the Lowest Water Level shown in Fig. 1.
(3) Open the air drain valve (V-6) and the backwash valve (V-4) and run the
backwash pump. After purging any air out (normally a few seconds) from the
backwash line, close the air drain valve (V-6) to feed back the filtrate waterfrom the backwash tank to the element.
The flow rate of backwash water is set up in advance normally for 1.1 to 1.5
times filtrate water flow rate.
It is acceptable to open the chemical feed valve (V-7) and run the chemical29

feed pump at the same time as running of the backwash pump.

! CAUTION- Do not impose the higher pressure to the element
than, the maximum applicable trans-membranepressure for backwashing, 200 kPa.
- Do not operate the element at higher temperaturethan the maximum applicable temperature, 40
degree C. The higher temperature damages theelement.

(4) At the same time, open the air-scrubbing valve (V-5) for air-scrubbing.

! CAUTION- The air flow rate for air-scrubbing should be within
the range below. Excessive air flow rate may
damage the membranes.
HSU-1515: 1.5 – 3.0 Nm3/h(5) After backwashing with air-scrubbing for a fixed time (normally 60 seconds),
close the air scrubbing valve (V-5), stop the chemical feed pump (if used) andthe backwash pump and close the chemical feed valve (V-7) and the backwash
valve (V-4).
(6) Open the drainage valve (V-3).
(7) Close the drainage valve (V-3) after backwashed water is drained out from thesubmerged tank.
(8) Open the feed water valve (V-1).
(9) After making sure the water level of the submerged tank is higher than the topof the filtrate piping, close the feed water valve (V-1).

30

4. Toray Maintenance Cleaning
Instead of chemical dosing for every backwash, soaking the membranes inchemical solution several tens of minutes a day is also effective for membrane
performance retention. This process is called Toray Maintenance Cleaning (TMC).
TMC is usually held following the backwash and air-scrubbing which does notcontain the chemical dosing. The frequency and the soaking time of TMC mainly
depend on the raw water quality (Normally once a day and each soaking time is 20
minutes. Please contact us if you need technical support.).

31

5. Air Diffuser Cleaning
The clogging of diffuser holes causes uneven air diffusion and membrane clogging,and the racks are broken in the worst case. Please clean the air diffusers once a
day to prevent such trouble.(it is recommended to install the automatic air diffuser
cleaning system with automatic valves).
The air diffusers are cleaned up with the reverse flow of the sludge from thediffuser holes into the diffuser pipes, which is generated by the air jet flow from thecompressor through the air diffuser pipes to the branch discharge nozzle.

Air diffuser cleaning procedure
Compressor
or Blower

Compressor
or Blower
V1
V3

V1

V2

V3

V4

V2

V4

open
close

Fig.12

Condition when air scrubbing

Fig.13

Condition when stop operation(1) After do the air scrubbing (Fig.12), close V1 and V2, open V3 and V4 valve(Fig.13). At this step, the water from the tank comes through the diffuser
holes into diffuser piping, and is discharged with the water (Stop operation).
(2) Keep this stop operation condition for about 5 seconds. After that, open V1
and V2 valve. At this step, the material deposit inside the diffuser holes anddiffuser tank will come out through V3 and V4 together with the water(Cleaning operation, see Fig. 14).

32

(3) After keeping the cleaning process

Compressor
or Blower

for about 5 seconds, stop theV1

V3

operation again. Repeat the stopV2

and cleaning process for about 5

V4

times, then close V1, V2 and V3
valves. Drain out the water inside
the tank, restart the feed andfiltration process.
(4) If the clogging occurs only on the

open
close

one of the air diffuser line, do thecleaning

only

for

repeating (1) – (3).
Fig. 14

Condition when cleaning process

33

that

line

by

6. Temperature Correction Factor
The permeability of the membranes is influenced by temperature mainly because
the water viscosity changes with temperature. When you evaluate the permeability
correctly, you need to eliminate the temperature effect with the temperaturecorrection factor (TCF) shown in Fig 15.
A Trans-Membrane Pressure (TMP) measured at some real temperature can beconverted to 25 degree C corrected TMP with multiplying by TCF at realtemperature shown in Fig. 15.
A filtrate flow rate measured at some real temperature can be converted to 25
degree C corrected filtrate flow rate with divided by TCF at real temperature shownin Fig. 15.
1.61.4
温度補正係数 (-)

1.2
Temperature

1.0

correction

0.8

factor

0.6
0.4
0.2
0.0
0

10
20
30
Feed water temperature
膜供給水温度 (℃)

Fig. 1540

Temperature correction factor (TCF)

The equation for calculating TCF at a temperature (T degree C) is as follows.
TCF= 0.0008902 / (0.01257187 x EXP((1−0.005806436 x (273.15 + T)) / (0.001130911
x (273.15 + T) - 0.000005723952 x (273.15 + T) x (273.15 + T))) / 1000)
Please contact us if you need to know how to measure the TMP.

34

VII. Integrity Test and Maintenance
1. Pressure Decay Test (PDT)
Pressure Decay Test (PDT) is recommended for testing the integrity of TORAY
Submerged PVDF Hollow Fiber Membrane Element. The PDT is conducted byapplying pressurized air to the element and monitoring the rate of pressure decay
over a specific duration of time.
PDT Flow Diagram
Below figure indicates a flow diagram for the PDT.

Membrane
Rack

P1

V-7

Filtrate
Water

Feed
raw water

V-4

H

V-1

V-5
Filtrate
Pump

V-6

P2
Backwash
Pump
Membrane
Submerged
Tank

V-2

P3

Air
FilterDrainage
V-3

Backwash
Tank
The air for
PDT
The air for
scrubbingFig. 16 Flow diagram for the PDTPDT Method(1)

Stop filtration to be tested. Ensure all of the elements are completely
submerged. Set the distance (H) of top of the element to water level of thesubmerged tank to approximately 0.1 m. Close all valves.

(2)

Set the PDT air pressure to a fixed value (P2=100 kPa) by using a regulator.

(3)

Introduce oil free air to the permeate side by opening the PDT valve (V-6).

(4)

Set the air pressure of the filtrate manifold to a fixed value (P1=100 kPa) byfine adjustment of the regulator. Close the PDT valve (V-6) when the air

35

pressure of filtrate header pipe is stabilized.
(5)

Monitor the pressure decay (Δp) of the feed air pressure for 5 to 10 minutes,
dependent on the number of elements. See Fig. 17 for examples of pressure
decay due to one broken membrane fiber. If pressure decay is excessive, avisual inspection of the element will be required (see step 7). The pressure
decay rate depends on the H. The Fig. 10 shows in case of H = 0.1 m.
Please correct the Fig. 17 by using the actual H.

(6)

Diffusion of air through the water filled pores of the membrane fiber leads toa pressure decay of approximately 1 kPa in 5 minutes (dependent on thevolume of the pipe work manifolds, etc.). A single broken membrane fiber in
128 HSU-1515 elements gives a pressure decay of approximately 5 kPa in 5
minutes, so a decay of 5 kPa in 5 minutes is normally used to indicate thepresence of a single broken membrane fiber for this size of unit.

(7)

In case of the pressure decay is excessiveness, identify the elements withbroken membrane fibers by visual check of water surface (bubbling) in thesubmerged tank. The pressure time should be kept within 15 minutes to keepfrom drying out of the membrane.

(8)

Mark any leaking elements for subsequent replacement.

(9)

After the 3 to 10 minutes pressure hold test period (or after identifying theelements with broken membrane fibers), relieve pressure in the permeateside of the membrane element by opening the air vent valve (V-7). If there
are elements with broken membrane fibers, dismount it after the pressure
release.

(10)

Open the backwash valve (V-5), run the backwash pump and vent air fromthe filtrate manifold through the V-7.

(11)

After venting air from the filtrate line, close the V-5 and the V-7, then stop the
backwash pump.

(12)

The unit is now ready for processing.

36

120
No. of element(HSU-1515)
100

1

Pressure, kPa

8
80

16
32

60

64
128
Diffusion Only (NoBreaks)

40

20

0
0

2

4

6

8

10

12

Pressure Decay Time, minutes

Fig. 17

HSU-1515 pressure decay rates with one broken membrane fiber (calculated)

NOTE: Above figure and indicates the estimate values. The actual values may
depend on the volume of the pipe work, temperature, etc.

37

VIII. Maintenance
1. Chemical cleaning
The chemical cleaning should be carried out to remove foulants accumulated in themembrane pores or sticking to the membrane surface.

! CAUTION- Carryoutthechemicalcleaning

beforethetrans-membrane pressure rises up to 70 kPa or atleast every 6 months, otherwise the element filtration
performance could be reduced significantly.
- Follow the instruction described in this manual when
you carry out the chemical cleaning. If you use theunacceptable chemicals or perform the cleaningaltered from the recommended procedure, themembranes could be seriously damaged.

! DANGER- Pay full attention when handling chemicals and be
sure to wear the safety gear such as glasses andgloves. The chemicals used for the chemicalcleaning are harmful to people. If chemicals directly
contact your skin, your eyes or other body parts, takethe appropriate treatment as stated in its MSDS.
- Do not mix sodium hypochlorite with acid. Suchmixture generates toxic chlorine gas.
- Stop operations when any instrumental anomalies
occur or any sign of anomalies are observed.

38

V-1

Membrane
Rack

V-6

Feed
raw water
V-2

V-4
Filtratewater

Filtratepump

V-5
Air forscrubbingMembrane
Submerged
Tank

V-3

CIP
pump
Drainage

Fig. 18

Backwashtank
CIP tank
V-9

Backwash
V-10
pump

V-11

Rinse water

Flow diagram for chemical cleaning(1) The flow diagram for cleaning simultaneously both outer surface and inside ofhollow fiber membranes is shown in Fig. 18. The flow diagram can be changed
case by case. Please contact us if you need the information in detail.
(2) After making sure the Backwash and Air-scrubbing process is just finished,open the drainage valve (V-3) and the air drain valve (V-6) to drain water of thesubmerged tank and the element.
(3) After making sure all water of the submerged tank is drained, close the drainage
valve (V-3).
(4) Open the Chemical valve (V-9) and the Cleaning In Place (CIP) valve (V-10)
and run the CIP pump to feed the chemical to the submerged tank.
(5) After making sure the chemical level of the submerged tank is higher than the
top of the membrane element, stop the CIP pump, close the Chemical valve(V-9) and the CIP valve (V-10) and hold the chemical for a fixed time (normally
2 hours). During the soak, open the air-scrubbing valve (V-5) a few times(normally every 30 minutes and each scrubbing time is 1 minute). In case of
the chemical cleaning efficiency is not high, a chemical circulation process fromfeed side to filtrate side (not shown in the figure) instead of the soak isavailable.

39

! CAUTION- The air flow rate for air-scrubbing should be within
the range below for each element. Excessive air flowrate may damage the membranes.
HSU-1515: 1.5 – 3.0 Nm3/h(6) Open the drainage valve (V-3) to drain the chemical out from the submergedtank completely and from the element almost completely.
(7) Close the drainage valve (V-3).
(8) Open the rinse valve (V-11) and the CIP valve (V-10), and run the CIP pump tofeed rinse water to the submerged tank for rinse.
(9) After making sure the water level of the submerged tank is higher than the topof the filtrate piping, stop the CIP pump and close the rinse valve (V-11) and the
CIP valve (V-10). Then open the air-scrubbing valve (V-5). After 30 seconds,
close the air-scrubbing valve (V-5).
(10) After 5 minutes, close the air drain valve (V-6) and then open the drainage
valve (V-3) to drain rinsed water out from the submerged tank completely.
(11) Close the drainage valve (V-3).
(12) Open the air drain valve (V-6) and the backwash valve (V-4), and run the
backwash pump. After purging any air out (normally a few seconds) from the
backwash line, close the air drain valve (V-6) to feed back the filtrate waterfrom the backwash tank to the element.
The flow rate of backwash water is set up in advance normally for 1.1 to 1.5
times filtrate water flow rate.
(13) Stop the backwash pump and close the backwash valve (V-4) when the waterlevel of the submerged tank reaches the top of the filtrate piping. Then open
the air-scrubbing valve (V-5). After 30 seconds, close the air-scrubbing valve(V-5).
(14) Open the drainage valve (V-3) to drain rinsed water out from the submergedtank completely.
(15) Repeat the process of (11) to (14) until make sure the submerged tank water
meets the required water quality.
(16) Close the drainage valve (V-3).
(17) Open the feed water valve (V-1).
(18) After making sure the water level of the submerged tank is higher than the top

40

of the filtrate piping, close the feed water valve (V-1).

- Take! CAUTION

appropriate

measurestopreventthemis-operation or accidents that could cause thechemicals to get into the product water. Check thepiping and correctly position of each valve before
starting the chemical cleaning.

(19) The standard conditions for chemical cleaning are shown in Table 5.
-

The concentration, the chemical quantity and the hold time shown in Table 5
should be observed. Otherwise the element may get damaged and/or the life ofmembranes may be shortened.

-

The cleaning temperature should be 20 to 40 degree C.
Table 5.

Standard conditions for chemical cleaning

Pollutants

Chemicals

Maximum
Concentration

Hold
Time

Inorganic
Substances

Citric acid *1

3.0 wt%1 - 3 hrOrganic
Substances

Sodium hypochlorite

3,000 mg/L
as chlorine(10 < pH < 12)

1 - 3 hr

*1: Besides citric acid, hydrochloric acid (with the maximum concentration of 1.0 mol/L),
oxalic acid (with the maximum concentration of 1.0 wt%), sulfuric acid (with the
maximum concentration of 0.05 mol/L) and nitric acid (with the maximum
concentration of 0.1 mol/L) are acceptable.

! CAUTION- In the case of cleaning with acid and with sodium
hypochlorite alternately, rinse the cleaning line andthe element with rinse water thoroughly after eachcleaning.

! DANGER- Do not use any other chemicals than those indicatedabove.
- Do not mix sodium hypochlorite with acid. Suchmixture generates toxic chlorine gas.

41

IX. Storage of New Element and Rack after use
Follow the instruction below when you store the element.

! CAUTION- Be careful not to freeze the element.

1. Storage of New Membrane Element
Keep the element in the original packing in a dark and cool place (0 – 40 degree
C).
Avoid direct sunlight and moisture.

2. Storage of Rack after use
In the case of the suspension of operation for less than three days, stop the feedwater, hold the water in the submerged tank and keep the water level of thesubmerged tank is higher than the top of the membrane rack. Keep the element
at 0 – 40 degree C.
If the suspension lasts more than three days, fill the submerged tank with thechemical described in Table 6. Use filtrate quality water. Replace the chemical
every maximum storage period described in Table 6. Keep the element at 0 – 40
degree C.
Table 6. Conditions for storing membrane rack for more than three days
Maximum
storage period

ChemicalConcentration of the
ChemicalStoragetemperature

3 dayssodium hypochlorite

20 mg/L as chlorine0 – 40 degree C

42This Instruction Manual does not intend to guarantee the results of application of theinformation provided herein or the safety and the compatibility of this product.
Before using this product, the user is asked to check for its safety and compatibility with
the intended purpose.
The content of this Instruction Manual is subject to revision from time to time.
Unauthorized use or reproduction of this manual is forbidden.

43