Water purification solutions - Prehrambeno-tehnoloÅ¡ki fakultet Osijek

Water purification solutions 

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Osijek, 06.10.2011. 

Prehrambeno-tehnološki fakultet u Osijeku 

Jasenka Ivanković, Merck d.o.o. Zagreb

Agenda 

- Water purification fundamentals 

- Water contaminants 

- Quality monitoring 

- Purification techniques 

- Standards and norms 

- Pure water production and storage, ultrapure water production 

Presentation title in footer | 00 Month 0000

Natural water sources 

Sea Water Iced Water Ground Water 

Lake Water Swamp Water River Water 


Water contaminants groups 

+ - INORGANIC IONS 

ORGANICS 

PARTICLES / COLLOIDS 

MICROORGANISMS 

DISSOLVED 

GASES 


From natural water to pure & ultrapure water 

Natural water contains 5 main classes of contaminants 

These contaminants, if they may have negative effects on human 

health, are removed down to a safety level by Water Companies 

Potable tap water still contains some of these contaminants, at levels 

that are not harmful for humans 

However, even at that level, these contaminants can be detrimental to 

laboratory instruments & experimentations 

These contaminants should therefore be monitored and removed to 

acceptable levels by appropriate techniques. 

When their effect on experimentation is unknown, they should be 

removed as much as possible (precaution principle) 


Water purification techniques 

+ - 

Contaminants Removal By 

Still DI EDI RO UF MF AC UV 254 

185 


Distillation 

Benefits 

Limitations 

Removes a large percentage of 

all types of contaminants 

Produces water with resistivity 

between 0.2 and 1 MegOhm.cm @ 

25°C and TOC between 50 and 

100 ppb 

Average investment 

Well known and perceived as 

easy to operate 

Not all contaminants are removed 

and several are generated during 

the process 

No control of water quality 

High operating costs due to 

electric heating (0.8KW/L) and 

water cooling (15 L tap water /L 

distilled water produced) 

Not ecologically friendly 

Regular maintenance (acid 

cleaning) or pretreatment (DI) is 

actually required to ensure 

optimum performance 


Deionization with single use mixed bed resin 

Benefits 

Effective at removing ions 

(Resistivity : 1 - 10 Megohm.cm 

with a single pass through the resin 

bed) 

Easy to use (simply open the tap 

and get the water) 

Limitations 

Does not eliminate particles, 

organic materials or 

microorganisms. 

Limited capacity depending on 

binding sites density and 

accessibility : requires good quality 

feed water to prevent premature 

exhaustion. 

Capacity related to flow rate 

Incorrect resin selection or 

multiple regeneration will cause 

water contamination by 

organic,particulate . 


Electrodeionisation (EDI) 

Benefit 

s 

Very efficient removal of ions and 

small MW charged organics (R> 5 

MegOhm.cm @ 25°C) 

Low energy consumption 

High water recovery 

Low operating cost 

Low maintenance 

No particulates or organic 

contamination (smooth, continuous 

regeneration by weak electric 

current) 

Moderate investment 

Limitations 

Requires good quality (RO) feed 

water to prevent plugging 

(particulates), fouling (organic, 

colloids) of ion-exchange resin 

beads. 

Solution required to prevent 

scaling at the cathode (early solution 

= softener) 

CO2 not totally removed if at high 

level in feed water. 


Reverse Osmosis 

Benefits 

Removes a fair percentage of all 

types of water contaminants (ions, 

organics, pyrogens, viruses, 

bacteria, particulates, colloids) 

Low operating costs due to low 

energy needs 

No need for strong acid and 

bases cleaning ; minimum 

maintenance 

Good control of operating 

parameters. 

Water consumption 2 to 10 times 

lower than stills (recovery up to 

66%) . 

Presentation title in footer | 00 Month 0000 

Limitations 

Not enough contaminants are 

removed to satisfy Type II 

requirements. 

Reverse Osmosis membranes 

are subject to plugging 

(particulates), fouling 

(organic,colloids), piercing (particle, 

chemical attack) and scaling 

(CaCO3) in the long run if not 

properly protected

Ultrafiltration 

Benefits 

Effective removal (>90%) of all 

organic molecules with molecular 

weight above the NMWL. Very 

efficient at removing pyrogens and 

Rnases (if validated) and viruses 

as well as particles. 

No risk of scaling ; limited risk of 

fouling. 

Low use of water and energy 

Low maintenance ; procedures 

well documented / accepted. 

Limitations 

Almost no rejection of ions, gases 

and low molecular weight organics 

(tightest UF membranes have a 

1,000 dalton cut-off 

BioPak 


Membrane (Screen) Microfiltration 

Benefits 

100 % removal of all 

contaminants (particulates, 

bacteria)larger than pore size. 

Integrity test available 

Sterilizing filtration (0.22 um 

membranes - LRV > 7) 

Minimum maintenance : simply 

replace when required. 

High flow rates are achievable at 

low pressure 

Efficiency independent of flow 

rate. 

Limitations 

Minimum effect on other 

contaminants 

Surface retention : may be 

subject to fouling/ plugging 


Activated Carbon 

Benefits 

Effective removal of a large 

range of organic substances (even 

of low molecular weight) by non 

specific binding (Van der Waals 

forces) or chlorine reduction 

Large capacity due to high 

developed surface 

Limitations 

Very little effect on other 

contaminants (except some 

particulates removed by depth 

filtration) 

Once all active sites are 

occupied, an equilibrium is 

established and organics are 

released. 

Bacteria may develop after 

several months. 

Efficiency depending on flow rate 


UV Technology (185 + 254 nm) 

Benefits 

Conversion of traces of organic 

contaminants to charged species 

and ultimately CO2 (185 + 254) 

Limited destruction of microorganisms 

and viruses (254) 

Limited energy use 

Easy to operate 

Limitations 

Polishing technique only: may be 

overwhelmed if organics 

concentration in feed water is too 

high 

Organics are converted, not 

removed. 

Limited effect on other 

contaminants 

Good design required for 

optimum performance. 


Technologies & Contaminants Removal 

IONS 

ORGANICS 

PARTICLE 

COLLOIDS 

BACTERIA 

GASES 

STILL DI RO UF MF AC UV 

Contaminant still 100% present (not removed) 

Contaminant completely (100%) removed

Main water purity criteria – resistivity and TOC 


Conductivity / resistivity measurement 

Conductivity and resistivity used to define the overall ionic purity/contamination 

Conductivity 

X = F∑c i z i µ i 

Conductivity 

(Siemens/cm) 

Faraday 

constant 

Concentration of each ionic 

species (eq/ml) 

Valence 

Mobility 

Ω -1 .cm -1 .s -1 

[H + ] = [OH - ] = 10 -7 M 

Minimum theoretical conductivity is 

0.055 µS.cm -1 at 25 °C 

Resistivity 

R 

= 

1 

X 

Maximum theoretical 

resistivity is 18.2 MΩ.cm at 25 °C 


Ultrapure water resistivity = f (t °C) 

18.2 

Resistivity (MΩ.cm) 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 


It is important to notify the temperature at 

which conductivity or resistivity 

measures are performed as those values 

are strongly dependent on temperature. 

At 25°C, ultrapure water 

resistivity = 18.2 MΩ.cm 

0 20 40 60 80 100 120 

25°C 

At 10°C, ultrapure water 

resistivity = 43.4MΩ.cm 

Temperature (°C)

Millipore resistivity meter: a unique design 

Electrodes 

Support 

block 

Thermistor 

Concentric electrodes design 

ensures reproducible manufacturing 

and stable cell constant. 

No dead legs: immediate response 

Made of high quality 316 L stainless 

steel 

Low cell constant 

(0.01 cm -1) for accuracy 

Protected thermistor 

Thermistor sensitivity = 0.1 °C 

Electronic autotest 

Alarms if defective parts 


Millipore Built-in Resistivity Meters 

Design allows to perform suitability test as 

required by USP (§ 645) 

Resistivity meter calibrated with traceability 

to internationally recognized primary 

standards 

Concentric electrodes design for cell 

constant stability 

Patented cell design 

US Patent Number: 

0405347000 

 

low cell constant (0.01 cm-1) 

Delivered with certificate of calibration 


Why TOC ? Because no correlation between 

resistivity & TOC level in ultrapure water 

+ sugar Monitoring 

Municipal tap 

water 

Polishing 

Reverse 

Storage 

Unit 

osmosis 

reservoir 

No UV 

20 

1200 

High purity 

water 

Resistivity, megohm.cm 

18 

16 

14 

12 

10 

8 

0 

0 30 60 90 120 150 180 210 240 

Time, minutes 

1000 

800 

600 

400 

200 

TOC, ppb 


Organics detection by TOC Monitor 

Built-in calibrated TOC Monitor 

TOC USP suitability testing: USP < 643> 


TOC Monitor – Calibration Certificate - 1 


Conclusion 

We have reviewed 2 water analytical methods that are well adapted to 

measure the ABSENCE of specific contaminants types in ultrapure 

water 

Resistivity measure allows to ensure on-line and in real time that ionic 

contamination of ultrapure water is below 1 µg/L level 

TOC measure allows to ensure that organic contamination is below the 

5 µg/L level 

Both methods, in order to deliver significant results, require: 

Proper design : adequate measure + alarms if defective measure 

Proper calibration 

Respect of established norms 

Merck Millipore meters meet those criteria and deliver therefore valid 

assurance of water quality 


Laboratory grade water norms 

Different laboratory water grades have been defined by different regulatory 

bodies: ASTM, ISO, USP, CLSI, CAP… 

The grades correspond to both applications & specifications 

Their role is both technical & economical 

- Technical: select the adequate water quality for a specific application 

- Economical: avoid selecting a quality that is too high for an application as 

the cost of laboratory grade water production increases with the water 

quality 


Water Quality Specifications 

Contaminant Parameter & unit Type 1 Type 2 Type 3 

Ions 

Resistivity 

(M Ω .cm) 

> 18.0 > 1.0 > 0.05 

Organics TOC (ppb) < 10 < 50 < 200 

Particulates Particulates > 0.2 

< 1 NA NA 

µm (units / ml) 

Silica Silica (ppb) < 10 < 100 < 1000 

Bacteria Bacteria (cfu/ml) < 0.1 < 100 < 1000 

Type 1 water 

HPLC and IC mobile phase preparation; blanks and sample dilution in GC, HPLC, AA , ICP-MS and 

other advanced analytical techniques ; preparation of buffers and culture media for mammalian cell 

culture, IVF, reagents for molecular biology... 

Complies with ASTM Type 1, ISO 3696 Grade 1, Pharmacopeiea

Type 3 water - basic laboratory applications 

Water baths 

Rotavapors 


Autoclaves

Type 2 water - regular laboratory applications 

Titrators 


pH Meters 

Regular lab 

solutions such 

as buffers 

Glassware 

Washers

Type 1 water - critical laboratory applications 

Molecular 

Biology 

Elemental 

Trace Analysis 

Cell Culture 

HPLC 


Production of Pure Water 

Type 3 and Type 2

Тype 3 water - pure water - RiOs systems 

Technologies: Pretreatment + Reverse Osmosis (+ UV optional) 

Systems: RiOs (3,5,8 and16 l/h) and Large RiOs (30, 50, 100, 150 and 200 l/h) 

Applications: 

Type 3 Laboratory-grade water is used in laboratories mainly for non-critical 

applications such as: 

- Glassware rinsing 

- Feed water for humidifiers, autoclaves, washing machines 

- Feed water for Milli-Q ultrapure water systems

RiOs principles 

Conductivity 

cells 

Optional 

on-line UV Lamp 

(254 nm) 

Storage 

Reservoir 

Pump 

MILLIPORE 

Tap 

Water 

Type 3 


1. Progard 

pretreatment pack to 

protect the RO 

membrane: 

• Activated Carbon 

(+ silver) against 

chlorine 

• Polyphosphate 

against scaling 

• Depth Filter against 

particulates 

Recovery 

Loop 

RO Reject 

Drain 

2. RO Cartridge 

(including sanitization 

port): 

Removes all types of 

contaminants up to 

98% (except gasses) 

Tank 

Point Of Use

Type 2 Water Systems & Applications 

Technologies: 

• Pretreatment 

• RO 

• EDI or DI 

• UV 

Type 2 Water Systems: 

• Elix 3, 5,10,15, 20,35,70,100 

• RiOs-DI 3 UV 

Applications: 

• Microbiology Media preparation 

• Feed to clinical analyzers 

• Chemical reactions run in water 

• Weatherometers 

• Washing machines 

• Histology 

• Feed to Ultrapure (Type 1) Milli-Q water 

systems

Electro - deionization (Elix technology) 

EDI module 

- Ion selective membranes 

- Ion exchange resins 

- Continuous current 

RO water 10-20µS 

A C A C 

Anode 

+ 

OH - 

H + 

Na 

+ 

Cl - 

Cl - Cl - 

Na+ 

H + OH - 

Cl - 

Cl - Na + 

Na+ - 

Cathode 

Reject 

A - Anionic Membrane 

C - Cationic Membrane 

Product 

Resistivity: > 10 MOhm.cm 

TOC: < 30 ppb

ELIX Water System Principles 

Conductivity 

cells 

Optional on-line 

UV Lamp (254 nm) 

Storage 

Reservoir 

Pump 

Resistivity 

cell 

MILLIPORE 

Tap 


Type 3 

Type 2 



1.Progard 

pretreatment pack to 

protect the RO 

membrane: 

• Activated Carbon (+ 

silver) against 

chlorine 

• Polyphosphate 

against scaling 

• Depth Filter against 

particulates 

Recovery 

Loop 

RO Reject 

Drain 

2. RO Cartridge 

(including sanitization 

port): 

Removes all types of 

contaminants up to 

98% (except gasses) 

EDI Reject 

3. EDI Module 

Removes remaining 

ions & small charged 

organic molecules 

5 < R < 15 MΩ.cm 

Type 2 

Point Of Use

ELIX Advantage System Principles On-line UV 

Lamp (254 nm) 

Storage 

Reservoir 

MILLIPORE 

Tap 


Type 3 


Type 2 


Recovery 

Loop 

Drain 

Recirculation 

Loop 

POD-Pak 

E-POD

2- ELIX E-POD 

Feature 

E-POD = Elix water Point Of Delivery 

Benefits for User 

1. Improved bacterial water quality 

ᅳ 

ᅳ 

ᅳ 

Less than 0.1 cfu/mL (with final filter) 

Recirculation on UV light 254 nm 

Recirculation up to the point of use – POU (no dead volume) 

2. Ergonomic design & ease of use 

ᅳ 

ᅳ 

ᅳ 

ᅳ 

ᅳ 

Pressurized Type 2 water dispensing up to 2L/min 

Adapted for manual rinsing as well as vessel filling 

Volumetric dispensing available & easily accessible 

Monitoring at a glance on the POD screen (quality, volume…) 

Printing Function 

3. Versatility for multiple applications or users 

ᅳ 

ᅳ 

ᅳ 

POD-Paks = several POU filters available for specific quality 

Up to 3 E-PODs connected to the same system 

No need to carry water around anymore!

Storage and distribution - Types 3 & 2 (pure) water 

Best practices for laboratory water storage

The storage challenge 

Your needs 

The options you have 

What is this 

water used for? 

Any quality 

requirements? 

How much 

water do 

you need, 

when? 

Do you need 

to distribute 

the water to a bench, 

an instrument? etc 

1.Size of reservoir and of system 

2. Right storage solution to 

maintain the best quality 

3. Options to get pure water 

where and when you need it

Small Storage Reservoir offer

Summary: Storage & Distribution Good Practices 

Intermittent recirculation 

while limiting temperature 

build up 

Recirculation Loop. 

UV 254 nm Lamp in 

the Tank (ASM) 

Sanitary overflow + 

vent filter. 

Conical bottom tank for 

complete emptying 

Maintains water quality during 

non-use periods. 

Avoids stagnation and maintains 

water quality. 

Prevents biofilm formation 

Reduces need for chemical 

sanitisation 

Introduction of clean filtered air 

during drawoff of water. 

Easy to clean

Production of ultrapure water – Type 1

Ultrapure water adapted to each application 

Tap water 

Pure water – Type 3 or 2 

Pretreatment step 

Polishing step 

Ultrapure water – Type 1 

Nuclease-free 

water 

Water for trace 

ion analysis 

Water for 

organic analysis 

Low bacteria 

water

STANDBY 

READY 

°C 

M Ω.cm@ Ω 

25°C 

ΩΩ 

ppb TO C 

L 

STANDBY 

READY 

°C 

M Ω.cm@ Ω 

25°C 

ΩΩ 

ppb TO C 

L 

STANDBY 

READY 

°C 

M Ω.cm@ Ω 

25°C 

ΩΩ 

ppb TO C 

L 

New Concept 

Several water 

qualities 

One central purification unit and several 

point-of-use purifiers 

Screen filter 

Ultrafilter 

Activated 

Carbon 

Standard high 

purity water 

Water with no bacteria 

by-products (endotoxins, 

nucleases, …) 

Water with very low 

volatile organic 

pollutants

Q-POD Dispenser 

The most critical 

purification step 

for the user 

application comes 

last

POD-Pak polishers for any application

Type 1 Water Systems and Applications 

Type 1 Water Systems: 

– Milli-Q Integral (with TOC monitor) 

– Milli-Q Direct (with TOC indicator) 

– Direct-Q 3 UV 

– Milli-Q Advantage A10 (with TOC monitor) 

Applications: 

– HPLC and IC mobile phase preparation 

– Blanks and sample dilution in GC, 

HPLC, AA , ICP-MS and other advanced 

analytical techniques 

– Preparation of buffers and culture media 

– Preparation of buffers and culture media 

for mammalian cell culture, IVF, 

reagents for molecular biology

Gradient profiles - water with various TOC levels 

20 ppb 

13 ppb 

9 ppb 

5 ppb 

2 ppb 

Increasing TOC 

levels result in 

more extraneous 

peaks and shifts 

of the baseline 

Important to 

know what’s 

the TOC level 

of the water 

you use in your 

mobile phase !

Water contaminants: 

Summary of effects on HPLC performance 

Contaminants 

Effects on HPLC 

Improper check valve operation 

Particles 

Damage to pump and injector 

Plugging of frits and column 

Organics 

Ions 

Bacteria 

Ghost peaks 

Increased background noise 

Drifting baselines 

Some ions absorb in the UV range (e.g., NO 3- , NO 2- ) 

With MS detectors: Na + , K + adduct peaks 

Plugging of frits and columns 

Ghost peaks

Summary of ISO 11131-1 : 

Type 2 water quality recommended for microbiology 

media preparation 

Since 99% of the culture media is water, water quality is critical. It should 

be: 

– free of nutrients 

– free of toxic substances 

– resistivity > 0.3 MΩ.cm (< 10 µS/cm) 

– low concentration of chlorine 

– low concentration of heavy metals 

– low microbial count

Water systems designed to serve your needs

Questions ?

Water purification solutions - Prehrambeno-tehnoloÅ¡ki fakultet Osijek

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