Charanda RO

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Reverse Osmosis and DeionizationSystems for Aquaria

Thoram Charanda

Sr. ChemistWalt Disney World Co.

Life Support

Lake Buena Vista, FL


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1st AQUALITY Symposium, April 2 - 7, 2004, Oceanario de Lisboa, Portugal

Reverse Osmosis and Desalination

1. Theory of Osmosis

2. Typical Industry Applications of ReverseOsmosis (RO), Desalination

3. Practical Considerations for RO in Aquaria

4. Designing an RO System for a Salt Water

Exhibit


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Theory of Osmosis

Fresh

Water

Sea

Water

H2O

Initial Condition

Fresh

Water

Sea

Water

(diluted)

H2O

Equilibrium

H2O

Semipermeable

Membrane

Fresh

Water

Sea

Water

H2O

Pressure

Reverse Osmosis

The Osmotic Pressure, , is defined as: = MRT

For sea water at 35 ppt, is about 350 psi.


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Key Terms in RO Systems

PermeateThe purified product water exiting the

system.

ConcentrateThe concentrated salt solution exiting the

system. In some system designs this outflow is returnedto the aquarium for salt recovery.

Feed FlowThe total flow rate of the source water

pumped in the system.

Recovery - The percentage of permeate achieved in a

system, % Recovery = permeate flow/feed flow x 100.

RejectionThe percentage of dissolved solids removed

from the source water by the membrane.


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RO Membrane Filter Detail


7/241st AQUALITY Symposium, April 2 - 7, 2004, Oceanario de Lisboa, Portugal

Industrial Applications of RO

Systems

Purification of potable or fresh water sources: Purified, very lowTotal Dissolved Solids (TDS) water is produced for various uses. Inthe aquarium industry it can be used for:

- Make up water in fresh and salt water aquariums

- As a pure water base for artificial salt water systems

- As a non-scaling/spotting wash or rinse water for aquarium exhibitwindows.

Desalination of Sea Water:

- Production of potable drinking

- Source water for combustible turbine power plants

- Irrigation and non-potable utility water uses

- It can also be used as a salt recovery system for closed-filtration seawater aquaria



RO System for Fresh Water

300 to 1,000 gallon per day

RO System

Requires a reservoir tank, high

level shut-off switch and

delivery pump

Pre-Filtration: Requires a 5-micron sediment filter and a

GAC filter to remove any

chlorine residual and organics



Desalination RO Systems



Design Considerations for a Salt

Recovery RO System Consider your feed water source: Natural or Artificial Sea Water.

Identify the typical range of the water chemistry parameters.

pH

Temperature Salinity

Silt Density Index (SDI)

Silica

Level of Particulates

Presence of Organics or Residual Oxidizers What is the desired rate of permeate (fresh water) removal from your

system? This will dictate the required feed flow rate for the ROsystem.



Design Considerations for a Salt

Recovery RO System Consider any future requirements for system upgrade in fresh water

removal capacity, e.g. system can accept an additional membrane,

high pressure pump is slightly oversized.

Identify the best location in the aquarium filtration pathway to connect

the feed source.

Consider connecting the return filtration line post ozonation.

Identify pre-filtration requirements:

GAC filter to removal residual oxidants, e.g. bromine, ozone Additional particulate filters for highly loaded systems



ROSA 5.4 Reverse Osmosis Design

Software

Specialized software can be used to assist in the initial

design and membrane performance parameters required for a

successful salt recovery system.

A freeware program is offered by DOW Chemical called

ROSA 5.4, that offers the ability to calculate the required

feed, permeate and concentrate rates based on the feed water

chemistry and a given sea water RO membrane type.

The URL for this program is www.filmtec.com.



5,000 gpd RO System at Shark Reef, Typhoon

Lagoon



Shark Reef Salinity Recovery: RO System

25

26

27

28

29

30

31

32

0 2 4 6 8 10 12 14 16 18 20

Days

Salinity

400,000

425,000

450,000

475,000

500,000

525,000

System

Volume(gal)

Salinity Volume (gal)

Initial Salinity = 30.4

Recovered Salinity = 30.3



Deionization Water Filtration Systems

1. Principles of Deionization (DI)

2. Applications for DI Water

3. Water Chemistry Parameters and Considerations

for a DI System



Ion Exchange Beads

Ion exchange beads are typically

constructed of a polymeric resin or gel

with an average diameter of 0.3 to 1.2

millimeters. The beads can have either

cationic or anionic functional groups

attached to the surface.



Types of Ionic Exchange Resins

Strong Acid Resins

- contain functional groups of R-SO3H on the

polymeric resin

Weak Acid Resins

- contain functional groups of R-COOH

Strong Base Resins

- contain functional groups of R-OH

Weak Base Resins

- contain functional groups of R-NH3



Strong Acid Cationic Resin

Polymeric ResinR-SO3-H

Na+

K+

Cu2+

Mg2+

Ca2+

Typical Cations

Metals

Fe2+

Zn2+



Applications for DI Water

Analytical grade water for laboratory use

Essentially salt and micro nutrient free water that can be

used to make artificial sea water Replenish system water loss due to evaporation

Makeup of specialized water quality environments, ie.

natural waters with very low TDS and specific

concentrations of cations



Design Engineering of DI Systems

Identify the source water for the DI system

Analyze for the key water chemistry parameters:

pH

Free and Total ChlorineTotal Dissolved Solids (TDS)

Identify the intended volume of DI required per day

A GAC prefilter is required to remove residual chlorine

and dissolved organics-typically sized from 0.0283 to 0.057 m3 (or 1 to 2 ft3)

Plan for a reputable company to provide an exchange

service for the mixed resin beds and GAC filter



Mixed bed ion exchange capacity = 353,357 grains per m3

10,000 grains per ft3

Design Engineering of DI Systems

Example: Your source water is potable city water and you require up

to 400 liters per day of DI water.

Source water TDS: 200 ppm

Equivalent grains per gallon = 11.7 gpg (divide TDS by 17.1)

Planned DI resin exchange frequency = 30 days

Minimum required amount of mixed bed resin = 0.105 m3

3.71 ft3



Summary

Reverse osmosis systems are a good design choice where:

- Moderate (2,000 liters) to large (+18 m3) volumes of water arerequired per event and there is sufficient space for the purified waterreservoir

- Desalinated water source for utilities and as a purified water sourcefor DI analytical laboratory grade water

- Desalination system for salt recovery

Deionization systems are a good design choice where:

- A relatively fast flow rate (> 35 Lpm) of pure water is required

- Only cost effective for relatively small exhibits, < 2,000 liters

- Analytical laboratory grade water


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Acknowledgements

Dow Chemical Company

GE Water Technologies

Reverse Osmosis of South Florida

US Filter Corporation

David Cohrs, National Aquarium in Baltimore

Kent Semmen, Brooksville Zoo

Eric Kingsley, Monterey Bay Aquarium

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