Disinfection-Siemens

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20111124 IEA Disinfection Seminar.ppt. Siemens Water ... Chlorine gas has an important role to play in the disinfection process and a high degree of safety has  ...

Disinfection P C Pre Conference f Workshop W k h EnviroVision 2011, IEA Annual Conference

Paresh Vora Disinfection Segment

For internal use only / Copyright © Siemens AG 2006. All rights reserved. Protection notice / Copyright notice Page 1

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

What are our objectives for disinfection?

Need for disinfection Reduction or elimination of pathogens, disease causing micro organisms.

Bacteria

Legionella

E-Coli E Coli

Typhoid

Viruses

Hepatitis A

Norwalk

Rotavirus

Cysts

Giardia

Cryptosporidium

Amoebic Dysentery

Zebra Mussels

Asiatic Clams

Control of biofouling that Microorganisms would affect the performance of the Microorganisms process Oxidation to create a chemical change that changes the characteristic of that contamination

Cholera

Bacteria Molluscs

Facilitate the Change colour & removal of a Reduce Toxicity d odour contaminate

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20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Water sources

Surface water

Ground water

A variety of water sources

Water reuse

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20111124 IEA Disinfection Seminar.ppt

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Factors that can influence disinfection efficiency

C Concentration t ti off pathogens th Contaminants reacting with disinfectants Concentration & dose rate of Disinfectants Available Contact Time pH & temperature

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20111124 IEA Disinfection Seminar.ppt

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Choice of chemical disinfection agents

Chlorine

AOP (Advanced Oxidation Process)

Chlorine Gas Sodium Hypochlorite yp Calcium Hypochlorite Electrochlorination

Chlorine Dioxide Oxidation Disinfection Agents ge ts

Bromine

Ozone

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20111124 IEA Disinfection Seminar.ppt

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Other Disinfectant Treatment

Ultraviolet Light

Biocides

Other Disinfectants

Physical Process (Filtration/ Membrane)

Ionizing radiation (Gamma) Protection notice / Copyright notice Page 6

20111124 IEA Disinfection Seminar.ppt

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The World Faces New Challenges

Resistance of certain Pathogens

New

Need to

Environmental

minimize

and Safety

disinfection by

Regulations

products

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20111124 IEA Disinfection Seminar.ppt

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Desired Disinfectant Characteristics

Effective against most known pathogens

Reasonable Cost

To be easily monitored and controlled

Multiple Barrier Approach

Provide protective Residual

Suitable for a wide range of water quality Protection notice / Copyright notice Page 8

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Chlorine gas ƒ Chlorine gas has an important role to play in the disinfection process and a high degree of safety has been built into today’s chlorine gas equipment. Advantages ƒ Effective against most pathogens ƒ

Provides a residual to protect against recontamination and bio-film

ƒ

Easily applied, controlled, and monitored

ƒ

Strong oxidant meeting most pre-oxidation objectives

ƒ

Operationally the most reliable/simple

ƒ

A very cost-effective disinfectant

Disadvantages ƒ

Byproduct formation (e.g (e g THM THM’ss,))

ƒ

Less effective against Cyst type organisms

ƒ

Requires transport and storage of chemicals

ƒ

Less effective at high pHs Protection notice / Copyright notice Page 9

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Commercial Sodium Hypochlorite Advantages ƒ Is supplied as a solution and easier to handle than chlorine gas ƒ Simpler training requirements and regulations ƒ Lower equipment/installation capital cost

Disadvantages ƒ Limited shelf-life (chlorate, chlorite and bromate) ƒ Adds inorganic byproducts (chlorate ƒ Storage consideration to prevent degradation ƒ Higher chemical & Transportation costs than chlorine gas

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20111124 IEA Disinfection Seminar.ppt

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On site Generation of Hypochlorite (OSEC) On-site Advantages ƒ Simple generation of Sodium Hypochlorite by electrolysis of brine ƒ Minimal chemical storage and transport of chemicals. ƒ Stable product ƒ Simple solution feed and control ƒ Control over quality and availability ƒ C Cost: t S Salt lt / El Electric t i / ttransportt vs. costt off chemical h i l such h as H Hypochlorite hl it Chlorine Gas & their transport / safety aspects Disadvantages ƒ

More complex than gas or bulk hypochlorite

ƒ

Requires higher level of maintenance

ƒ

Higher capital cost

(although various financial schemes in place) Protection notice / Copyright notice Page 11

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Chlorine Dioxide Advantages 1. Highly effective effective disinfectant & oxidant 2. Effective from pH 2.0 – 10.0 3. Does not react with ammonia or bromides 4. Does not chlorinate organics to produce THM’s & THAA’s 5. Effective at low dosage rate: ƒ

Potable Water: ~ 0.5 to 1.5 PPM to raw incoming surface water

ƒ

Potable Water: ~ 0.2 0 2 to 0 0.4 4 PPM to distribution system

ƒ

Wastewater:

~ 2.0 to 5.0 PPM

Controls viruses, algae, bacteria, fungi and protozoa Includes cryptosporidium, giardia, e-coli, salmonella, chlorea, mollusks Disadvantages 1. Handling of chemicals 2. Process not widely understood Protection notice / Copyright notice Page 12

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

UV Disinfection Advantages

ƒ Non chemical approach to disinfection. ƒ Effective against a wide variety of microorganisms, viruses, bacteria, fungi and protozoans. protozoans

ƒ UV is a proven method for effectively treating Cryptosporidium and Giardia ƒ Reduces the risks and hazards associated with on-site storage, handling and transportation of chlorine and other toxic or hazardous chemicals

ƒ Requires a shorter contact time when compared to other disinfectants ƒ Does not effect the aesthetic qqualityy of the water ((T & O))

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20111124 IEA Disinfection Seminar.ppt

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UV Disinfection Limitations

ƒ ƒ ƒ ƒ

N residual No id l protection t ti ffor di distribution t ib ti system t ((municipal i i ld drinking i ki water) t ) Not effective as a preoxidant, for taste and odor control High doses required for some viruses, e.g. adenovirus Not effective if large particles are present

Waste Water installation

Drinking Water installation Protection notice / Copyright notice

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20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Chlorination – Automation Example

CAN –Easy Easy Connectivity

Improve control by “trimming” chemical feed after the chlorine contact tank Protection notice / Copyright notice Page 15

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Chlorination – Dechlorination Automation Example

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20111124 IEA Disinfection Seminar.ppt

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Distribution system monitoring Effective distribution monitoring

Battery powered analyzer that measures: Chlorine Æ Chloroclam Temperature } P Pressure }H Hydroclam d l Conductivity } Turbidity } Connects to hydrants or to a ‘T’ on the main Options to provide remote outputs Protection notice / Copyright notice Page 17

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Gas Chlorination Example – Small Capacity

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20111124 IEA Disinfection Seminar.ppt

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Gas Chlorination Example – Large Capacity 1/2

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20111124 IEA Disinfection Seminar.ppt

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Gas Chlorination Example – Large Capacity 2/2

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20111124 IEA Disinfection Seminar.ppt

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Hypochlorite Dosing / Electrochlorination Example – 1/2

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20111124 IEA Disinfection Seminar.ppt

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Hypochlorite Dosing / Electrochlorination Example – 2/2

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20111124 IEA Disinfection Seminar.ppt

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On-Site On Site Hypochlorite Generation Chemistry

NaCl + H2O + Electricity 3.5 kg Salt (NaCl)

+

Water

+

4.5 kWh electricity

NaOCl + H2

=

1 kg of chlorine equivalent;125 litres lit off 0 0.8% 8% sodium hypochlorite

+ 612 litres waste hydrogen Protection notice / Copyright notice Page 23

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

On-Site On Site Hypochlorite Generation Process

WATER

UPSTREAM

CORE

WATER

CHILLER

SOFTENER

OR HEATER

BRINE

SALT

ELECTROLYZER

PREP TANK

DOWNSTREAM

BLOWER

HYPOCHLORITE TANK

AIR

H2 GAS

Saturated Brine 26%

POWER

TRANSFORMER

DOSING

RECTIFIER

EQUIPMENT

HYPO

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20111124 IEA Disinfection Seminar.ppt

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Chlorinedioxide Generation – Precursor Chemicals Produced from one of two precursors ƒ Sodium chlorate (NaClO3) ƒ Sodium S di chlorite hl it (N (NaClO ClO2) Chemistry is either… ƒ Acid conversion using mineral or organic acids ƒ Conversion involving chlorine in some form: gaseous chlorine; aqueous chlorine; sodium hypochlorite plus acid to produce chlorine in the generator

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20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Chlorinedioxide Generation – Chemistry Options ƒ Acid Chlorite – Liquid Phase 5 NaClO2 + 4 HCl --> 4 ClO2 + 5 NaCl + 2H2O Actual conversion of chlorite - Lower ƒ Aqueous Chlorine Chlorite – Liquid Phase 2 NaClO2 + Cl2Æ 2 ClO2 + 2 NaCl Actual conversion of chlorite - Low ƒ Molecular Chlorine Chlorite – Vapour Phase 2 NaClO2 + Cl2Æ 2 ClO2 + 2 NaCl Actual conversion of chlorite – High ƒ Acid Hypochlorite Chlorite – Vapour Phase 2 NaClO2 + NaOCl + 2 HCl Æ 2 ClO2 + 3NaCl + H2O Actual conversion of chlorite – High Protection notice / Copyright notice Page 26

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

2 Chemical Vapour Phase Generation Eductor

H2O

ClO2 Reaction Column

Chlorite

Chlorine

2 Chemical Systems “Vapor Vapor Phase Phase” Cl2 and 25% Sodium Chlorite (or acid – chlorite system with larger reaction column and pH control) Protection notice / Copyright notice Page 27

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Comparision Vapour - Liquid Phase ƒ Chemistry: 2 Chemical “Vapor Phase” chlorine gas / chlorite - Simplest p and most efficient chlorite process p 2NaClO2

+

Cl2

2ClO2

+

2NaCl



Maximum theoretical yield = 100%



Practical yyield = 95-98%



Molar conversion efficiency from chlorite = 95-98%



One mole sodium chlorite goes to 1 mole chlorine dioxide

ƒ Chemistry: Ch i t 2 Ch Chemical i l “HCl – Chlorite” Chl it ” process 5 NaClO2 + 4 HCL -> 4 CLO2 + 5 NaCl + 2 H20

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Maximum theoretical yield = 100%



P ti l yield Practical i ld = 60 tto 80%



Maximum theoretical molar conversion efficiency = 80%



5 moles sodium chlorite -> 4 moles CLO2



20% more sodium chlorite required to produce 1 lb CLO2



pH of reaction must be driven to 3.0 to 3.5



Rx is temp dependent

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20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

3 Chemical Vapour Phase Generation

Eductor

ClO2

H2O Reaction C l Column

Chlorite

Cl2 Formation

Bleach

Acid

3 Chemical Systems p Phase” In-situ Cl2 and 25% Sodium Chlorite “Vapor Protection notice / Copyright notice Page 29

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Comparision Vapour - Liquid Phase ƒ Chemistry: 3 Chemical “Vapor Phase” - Generation of chlorine in situ - Instantaneous two step reaction (1) NaOCl

+

2HCl

(2) 2NaClO2 + Cl2

Æ

Cl2 + NaCl + H2O

Æ

2ClO2 + 2NaCl

Maximum theoretical yield = 100% Practical yield = 95-98% Molar conversion efficiencyy = 95-98% ((from sodium chlorite)) Advantages of Vapour phase technology ƒ Gives most effective conversion of chlorite to ClO2 ƒ Low chemical costs relative to others ƒ Instantaneous generation under vacuum ƒ Little or no acid contaminant (little pH depression). ƒ Inherently safe, vacuum driven Protection notice / Copyright notice Page 30

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Chlorine dioxide Example

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20111124 IEA Disinfection Seminar.ppt

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Ultraviolet Systems - Example

VR / VE - Vertical Channel Mounted

HR / HE - Horizontal Channel Mounted

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20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Summary

The disinfectant should be chosen to suit the application

Each one of the disinfectants has its advantages & disadvantages

Analysers,controllers Analysers controllers & automation are now an essential part of the process

A multiple barrier approach provides a cost effective solution with added security of disinfection

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20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies

Thank you for your attention!

[email protected] Protection notice / Copyright notice Page 34

20111124 IEA Disinfection Seminar.ppt

Siemens Water Technologies