Reverse Osmosis Reverse Osmosis Background to Market and to Market - - PowerPoint PPT Presentation

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Reverse Osmosis Reverse Osmosis

Background Background to Market and to Market and Technology Technology

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Technology and Applications Technology and Applications

  Reverse osmosis has been commercial for

Reverse osmosis has been commercial for

• ver 25 years.
• ver 25 years.

  60MLD plants built in Saudi Arabia 20 years

60MLD plants built in Saudi Arabia 20 years ago. ago.

  Current sales of RO membranes world

Current sales of RO membranes world-

• wide

wide are around $250 million per annum are around $250 million per annum excluding Japan. excluding Japan.

  RO System sales could be as high as $1.0b

RO System sales could be as high as $1.0b per annum per annum

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Membrane Market Membrane Market

  Growth sector of the water treatment industry driven

Growth sector of the water treatment industry driven by reduced energy consumption and increased by reduced energy consumption and increased awareness of environmental impact/cost of ion awareness of environmental impact/cost of ion exchange operation exchange operation

  Growth at 15

Growth at 15-

• 18% per annum

18% per annum

  Main manufacturers are from USA

Main manufacturers are from USA

• Dow/

Dow/Hydranautics Hydranautics/Fluid Systems /Fluid Systems USA USA

• Koch/

Koch/Dupont/Osmonics/Trisep Dupont/Osmonics/Trisep Japan Japan

• Nitto Denko/Toray/Toyobo

Nitto Denko/Toray/Toyobo

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Fundamentals Fundamentals

• f Membranes and
• f Membranes and

Reverse Osmosis Reverse Osmosis

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Membrane Separation Membrane Separation

1 2 3 5 10 8 100 1000 104 10 5 10 6 107 Beach Sand Pollens Bacteria Viruses Colloids Sugars Aqueous Salts

Particle Filtration Microfiltration Ultrafiltration

Nano- Filtration

Angstrom

Reverse Osmosis

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Membrane Membrane Typical Operating Typical Operating Process Process Pressure Range (PSI) Pressure Range (PSI) Reverse Osmosis Reverse Osmosis seawater seawater 800 800 -

• 1200

1200 brackish water brackish water 100 100 -

• 600

600 Nanofiltration Nanofiltration 50 50 -

• 225

225 Ultrafiltration Ultrafiltration 30 30 -

• 100

100 Microfiltration Microfiltration 2 2-

• 45

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Pressure Driven Membrane Pressure Driven Membrane Processes Processes -

• Pressures

Pressures

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Impurities in Water Impurities in Water

  Ionic

Ionic

  Non Ionic

Non Ionic

  Particulate

Particulate

  Microbiological

Microbiological

  Gases

Gases

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RO Removes RO Removes

  Ionic

Ionic

  Non ionic

Non ionic

  Particulate

Particulate

  Microbiological

Microbiological

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When to Consider RO When to Consider RO

  Water with TDS greater than 150 mg/L

Water with TDS greater than 150 mg/L

  Regenerant

Regenerant cost reduction cost reduction

  Waste cost reduction

Waste cost reduction

  Water conservation or recovery

Water conservation or recovery

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Not feasible for reverse osmosis

A rises to equal  B sparingly soluble solutes precipitate and foul the membrane

Pressure Filtration Pressure Filtration

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Required for reverse osmosis and nanofiltration

A sweeps away membrane foulants B minimizes concentration polarization (maintains –  difference) C generates a concentrate stream and a permeate stream

Cross Flow Filtration Cross Flow Filtration

0.2 0.2 µ µm m 40 40 µ µm m 120 120 µ µm m

Polyamide Polyamide Polysulfone Polysulfone Ultrathin Ultrathin Barrier Layer Barrier Layer Microporous Microporous Polysulfone Polysulfone Reinforcing Reinforcing Fabric Fabric

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Cross Cross-

• Section of Thin

Section of Thin-

• film

film Composite Membranes Composite Membranes

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Thin Thin-

• film Composite

film Composite Membrane Chemistries Membrane Chemistries

  Typical composition

Typical composition

  Fully aromatic polyamide (Dow FT30)

Fully aromatic polyamide (Dow FT30)

  Polypiperazineamide

Polypiperazineamide (Dow NF45) (Dow NF45)

  Polyvinyl alcohol (

Polyvinyl alcohol (Hydranautics Hydranautics) )

  Sulfonated

Sulfonated polysulphone polysulphone ( (Ionpure Ionpure) )

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Permeate Channel Barrier Layer

HOLLOW FINE FIBRE PERMEATORS

Schematic Cross Section Schematic Cross Section

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Spiral Wound Reverse Spiral Wound Reverse Osmosis Osmosis

Brine Channel Spacer Product

Water

Membranes Permeate

Channel Spacer Water Flow Feed Brine Brine Product Water Brine Seal

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Reverse Osmosis Reverse Osmosis

Feed Ions Concentrate Product Water Flow

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Nanofiltration Nanofiltration Definition Definition

  Minimum size rejected on order of one

Minimum size rejected on order of one nanometer nanometer

  Between RO and UF

Between RO and UF

  Operates at ultra

Operates at ultra-

• low pressure

low pressure

  Selective permeation of ionic salts and

Selective permeation of ionic salts and small solutes small solutes

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Nanofiltration Nanofiltration

Feed Macromolecules Monovalent Ions Concentrate Product Water Flow Polyvalent Ions

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Concentrated Solution Pure Water

Osmotic Processes Osmotic Processes

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Osmosis

Concentrated Solution Pure Water

Osmotic Processes Osmotic Processes

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Reverse Osmosis

Pressure Concentrated Solution Pure Water

Osmotic Processes Osmotic Processes

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Reverse Osmosis Involves Reverse Osmosis Involves

  Application of pressure greater than

Application of pressure greater than

• smotic pressure of solution
• smotic pressure of solution

  Diffusion of water but not salt through a

Diffusion of water but not salt through a semipermeable semipermeable membrane in direction membrane in direction

• pposite of natural flow
• pposite of natural flow

  Crossflow

Crossflow filtration to sweep away filtration to sweep away concentrated salts concentrated salts

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Reverse Osmosis: Reverse Osmosis: What It Can Do What It Can Do

  Remove purified water from a feed stream

Remove purified water from a feed stream (permeate) (permeate)

  Concentrate chemicals in a feed stream

Concentrate chemicals in a feed stream (reject) (reject)

  Selectively separates small ions and

Selectively separates small ions and molecules molecules

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Reverse Osmosis: Reverse Osmosis: What It Cannot Do What It Cannot Do

  Cannot concentrate to 100%

Cannot concentrate to 100%

  Cannot separate to 100%

Cannot separate to 100%

  Cannot reject gases

Cannot reject gases and is and is Not always the most cost effective method Not always the most cost effective method

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Mass Balance Equations Mass Balance Equations

Recovery (%) = Recovery (%) = Salt Passage (%) = Salt Passage (%) = Salt Rejection (%) = 100 Salt Rejection (%) = 100 -

• Salt Passage

Salt Passage Permeate flow Permeate flow Feed flow Feed flow x 100 x 100 Permeate Salt Concentration Permeate Salt Concentration Feed Salt Concentration Feed Salt Concentration x 100 x 100

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Normalization of Normalization of Field Operating Data Field Operating Data

  Feedwater

Feedwater pressure pressure

  Temperature

Temperature

  Ionic concentration

Ionic concentration

  System recovery

System recovery

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2 4 6 8 10 12 60 50 40 30 20 100 99 98 97 96 pH Salt Rejection (%) Water Flux (GFD)

Data from DOW Filmtec

pH pH vs vs Flux and Salt Rejection Flux and Salt Rejection

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Data from DOW Filmtec

200 400 600 800 1000 1200 40 30 20 10 100 99 96 94 92 Pressure (PSI) Salt Rejection (%) Water Flux (GFD)

Pressure Pressure vs vs Flux+Rejection Flux+Rejection

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Temperature v Temperature v Flux+Rejection Flux+Rejection

Data from DOW Filmtec

10 20 30 40 50 60 100 80 60 40 20 100 99.5 99 98.5 98 Temperature (°C) Salt Rejection (%) Water Flux (GFD)

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Salinity Salinity vs vs Flux and Flux and Rejection Rejection

Data from DOW Filmtec

2 4 6 8 10 80 60 40 20 99.5 99 98.5 98 97.5 Percent Salt Rejection (%) Water Flux (GFD)

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Factors Which Affect Factors Which Affect Performance of Membranes Performance of Membranes

  Feedwater

Feedwater Pressure Pressure

  Feedwater

Feedwater Temperature Temperature

  Feedwater

Feedwater Concentration Concentration

  Increased Recovery

Increased Recovery

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Simplified RO System Simplified RO System

Pump Pump Concentrate Concentrate Permeate Permeate Feed Feed Water Water 100 to 400 100 to 400 psi psi (brackish water) (brackish water) 800 to 1,200 800 to 1,200 psi psi (seawater) (seawater)

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Feed Permeate Reject (Brine)

Membrane Performance Membrane Performance

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Feed Permeate Reject (Brine)

Membrane Performance Membrane Performance

100 m3/hr 25 m3/hr 75 m3/hr 75% Recovery

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RO Pretreatment Options RO Pretreatment Options

  Suspended Solids Removal

Suspended Solids Removal

  Clarification

Clarification

  Filtration

Filtration

  Primary Membrane UF/MF/EDR

Primary Membrane UF/MF/EDR

  Control of biological activity

Control of biological activity

  Chlorination/

Chlorination/dechlorination dechlorination

  Chloramines

Chloramines

  Non

Non Oxidising Oxidising Biocides Biocides

  Ultraviolet Light

Ultraviolet Light

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RO Pretreatment Options RO Pretreatment Options

  Scale control & pH adjustment

Scale control & pH adjustment

  Antiscalant

Antiscalant Addition Addition

  Acid Addition

Acid Addition

  Ion Exchange Pretreatment

Ion Exchange Pretreatment

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RO Systems Design RO Systems Design

  Module (Element): Contains Membrane

Module (Element): Contains Membrane

  Tube:

Tube: Modules in Series (1 Modules in Series (1 -

• 7)

7)

  Stage:

Stage: Set of Tubes in Parallel Set of Tubes in Parallel

  Array:

Array:

• No. of Stages, Tubes/Stage
• No. of Stages, Tubes/Stage

  Train:

Train: Set of all of the Above Set of all of the Above

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FEED PERMEATE CONCENTRATE 1st stage 2nd stage 50% MAXIMUM RECOVERY per STAGE 75% RECOVERY 4:2 ARRAY 2 STAGES 1 TRAIN 40 m3/hr 20 m3/hr 20 m3/hr 10 m3/hr 10 m3/hr

RO System Flow Diagram RO System Flow Diagram

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Other Factors to be Aware of.. Other Factors to be Aware of..

  One to seven elements per pressure vessel

One to seven elements per pressure vessel

  Maximum feed flow

Maximum feed flow – – physical limitations physical limitations

  Minimum brine flow or maximum ratio of

Minimum brine flow or maximum ratio of permeate flow to feed flow permeate flow to feed flow – – concentration concentration polarization polarization

  Recovery

Recovery

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Other Factors to be Aware of.. Other Factors to be Aware of.. System Design Guidelines System Design Guidelines

  Fouling and/or scaling tendency of feed

Fouling and/or scaling tendency of feed most influences system design most influences system design

  Tendency for fouling increases with

Tendency for fouling increases with increasing permeate flux and increasing increasing permeate flux and increasing element recovery element recovery

  Only experience can set limits on permeate

Only experience can set limits on permeate flux and element recovery for specific feed flux and element recovery for specific feed

  Use system design guidelines when

Use system design guidelines when previous experience is not available previous experience is not available

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Other Factors to be Aware of.. Other Factors to be Aware of.. Feed Composition on System Feed Composition on System Recovery Recovery

  Seawater recovery limitations

Seawater recovery limitations

  High osmotic pressure

High osmotic pressure

  Osmotic pressure limits recovery

Osmotic pressure limits recovery to 35 to 35-

• 45%

45%

  Brackish water recovery limitations

Brackish water recovery limitations

  Brackish water chemistry tends to

Brackish water chemistry tends to contain many sparingly soluble salts contain many sparingly soluble salts which cause scaling which cause scaling

  Usually limits recovery to 70

Usually limits recovery to 70-

• 85%

85%

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Factors Which Affect Factors Which Affect Performance of Membranes Performance of Membranes

  Feedwater

Feedwater Pressure Pressure

  Feedwater

Feedwater Temperature Temperature

  Feedwater

Feedwater Concentration Concentration

  Increased Recovery

Increased Recovery

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Troubleshooting Troubleshooting

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Overview Overview

  The Importance of Record Keeping

The Importance of Record Keeping

  The General Rule of Troubleshooting

The General Rule of Troubleshooting

  Signs of Trouble

Signs of Trouble

  Causes and Corrective Measures of Trouble

Causes and Corrective Measures of Trouble Signs Signs

  Taking the Total System Approach

Taking the Total System Approach

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Why Keep Records? Why Keep Records?

  Necessary for observing trends

Necessary for observing trends

  Valuable tool for troubleshooting

Valuable tool for troubleshooting

  Required

Required in the event of a warranty claim in the event of a warranty claim

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General Rule of General Rule of Troubleshooting Troubleshooting

  First Stage Problem

First Stage Problem -

• Fouling

Fouling

  Last Stage Problem

Last Stage Problem -

• Scaling

Scaling

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Troubleshooting Troubleshooting

  Signs of trouble

Signs of trouble

 Loss of permeate flow

Loss of permeate flow

 Increase in salt passage

Increase in salt passage

 Increase in differential P

Increase in differential P

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Probing Probing

  Procedure to determine problem area in pressure

Procedure to determine problem area in pressure vessel without unloading elements from vessel vessel without unloading elements from vessel

  Probe if one pressure vessel shows a significantly

Probe if one pressure vessel shows a significantly higher permeate TDS than other vessels of the same higher permeate TDS than other vessels of the same array array

  Plot TDS measurements on a conductivity profile to

Plot TDS measurements on a conductivity profile to determine problem area in vessel determine problem area in vessel

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Conc. Permeate Feed

conductivity

12 14 80 32

Troubleshooting Troubleshooting -

• Probing

Probing

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50 50 50 50 50 50 50 52 52 52 52 52 52 51 51 51 49 49 49 49 49 75 91 51 99 99 99 99 97 97 97 97 101 97 97 325

Troubleshooting Troubleshooting -

• System

System

  Best recorded by preparing a series of

Best recorded by preparing a series of circles arranged similar to the vessel rack circles arranged similar to the vessel rack assembly and writing each vessel assembly and writing each vessel’ ’s reading s reading in its respective circle. in its respective circle.

  Example: 24:12 array at 75% recovery

Example: 24:12 array at 75% recovery

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High Differential Pressure High Differential Pressure

² ²P is a measure of the resistance to the hydraulic P is a measure of the resistance to the hydraulic flow of water through the system. This is very flow of water through the system. This is very dependent on flow rates through the element dependent on flow rates through the element brine flow channels and on water temperature brine flow channels and on water temperature Lead element brine flow channels will show Lead element brine flow channels will show debris, debris, foulants foulants, and , and scalants scalants

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High Differential Pressure High Differential Pressure

  Causes

Causes

  Cartridge filter by

Cartridge filter by-

• pass

pass

  Media filter breakthrough

Media filter breakthrough

  Pump impeller deterioration

Pump impeller deterioration

  Scaling

Scaling

  Brine seal damage / improper placement

Brine seal damage / improper placement

  Biological fouling

Biological fouling

  Precipitated

Precipitated antiscalants antiscalants

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High Differential Pressure High Differential Pressure

  Cause: Cartridge Filter By

Cause: Cartridge Filter By-

• pass

pass

  Filter improperly installed

Filter improperly installed

  Avoid cellulose

Avoid cellulose-

• based filters

based filters

  Corrective Measure:

Corrective Measure:

  Properly install cartridge filter

Properly install cartridge filter

  Clean filter housings when replacing

Clean filter housings when replacing filters filters

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Taking the Total System Taking the Total System Approach Approach

  Troubleshooting Steps

Troubleshooting Steps

  Investigate

Investigate

  Evaluate

Evaluate

  Solve

Solve

  Prevent

Prevent

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Troubleshooting Troubleshooting

  Investigate entire system

Investigate entire system

  Review normalized operating data

Review normalized operating data

  Check

Check feedwater feedwater quality quality

  Confirm chemical dose rates

Confirm chemical dose rates

  Calculate material balance

Calculate material balance

  Calibrate instruments, i.e. flow meters

Calibrate instruments, i.e. flow meters

  Try to localize problems for further in

Try to localize problems for further in-

• depth

depth evaluation evaluation

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If Source of Problem is If Source of Problem is Not Identified Not Identified

  Check conductivities and probe if necessary

Check conductivities and probe if necessary

  Remove and inspect first element, first stage and last

Remove and inspect first element, first stage and last element, last stage element, last stage

  Look for mechanical damage (torn O

Look for mechanical damage (torn O-

• ring, cracked

ring, cracked fiberglass) fiberglass)

  Visually inspect elements; send to Anjou

Visually inspect elements; send to Anjou Recherche Recherche for autopsy if necessary for autopsy if necessary

  Determine effect of first high pH then low pH

Determine effect of first high pH then low pH cleaning cleaning

  Analyze cleaning solutions for metals and TOC

Analyze cleaning solutions for metals and TOC

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If Source of Problem is Still If Source of Problem is Still Not Identified Not Identified

  Conduct a destructive autopsy of the

Conduct a destructive autopsy of the elements: elements:

  Check for metals and organics on membrane

Check for metals and organics on membrane surface surface

  Conduct dye test for oxidative damage to the

Conduct dye test for oxidative damage to the membrane membrane

  Visually examine the element for physical damage

Visually examine the element for physical damage (wrinkles, glue line separation, etc.) (wrinkles, glue line separation, etc.)

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Clean In Place System Clean In Place System

  9 m3/hr per pressure

9 m3/hr per pressure vessel vessel

  >4 bar Pressure

>4 bar Pressure

  In Line Filter

In Line Filter

  Heater System

Heater System

  35

35-

• 70

70 Litres Litres per per element to be cleaned element to be cleaned

  Return Line below

Return Line below liquid in Tank liquid in Tank

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Design Faults with CIP Design Faults with CIP

  Insufficient Flow

Insufficient Flow

  Excessive Pressure

Excessive Pressure

  Tank Heating Capacity too Small or Omitted

Tank Heating Capacity too Small or Omitted

  Lack of Appropriate Monitoring

Lack of Appropriate Monitoring -

• Flow/Pressure

Flow/Pressure

  Plant Cannot be Cleaned in Stages

Plant Cannot be Cleaned in Stages

  Contents of Tank Cannot be Diverted

Contents of Tank Cannot be Diverted

  Procedure Recommends incorrect Products

Procedure Recommends incorrect Products for Fouling for Fouling

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Monitoring Requirement Monitoring Requirement

  Feed System (by stage)

Feed System (by stage)

  Salinity Concentration

Salinity Concentration

  pH

pH

  Temperature

Temperature

  Permeate

Permeate

  Concentration/Flow/

Concentration/Flow/PressurePressure PressurePressure

  Concentrate

Concentrate

  Flow/Pressure and Concentration

Flow/Pressure and Concentration (optional) (optional)