Water Treatment ProcessesDisinfection and removal of solids

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Contents

1. Aim of treatment

2. Removal of solids in suspension

3. Disinfection

4. Water treatment in emergencies

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1.Aim of treatment

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Multiple options of treatment

Safe water supply: “All people have safe and equitable access to a sufficient quantity of water for drinking, cooking and personal and domestic hygiene.”

“Water is palatable, and of sufficient quality to be drunk and used for personal and domestic hygiene without causing significant risk to health”

(The Sphere Project, Chap.2, Norms 1 y 2 )

1. Aim of the treatment process

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Pathogen free

Chemically safe

Without dirt solid matter

Aesthetically acceptable

WHO Guidelines

National Regulation

1. Aim of the treatment process

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The treatment process starts in the water extraction

Source selection (surface water/groundwater)

Means of water extraction (strainer)

The treatment process ends in the distribution

Storage and distribution

Jerry cans for the beneficiaries

Re-contamination risks

1. Aim of the treatment process

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2. Removal of solids in suspension

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Why? - aspect

- efficiency of

disinfection

Control parameter: Gravity analysis

Turbidity (NTU)

Aim: < 5 NTU

Methods

Sedimentation

Flocculation

Filtration

2. Removal of solids in suspension

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Advantages: Simple, no consumption

Disadvantages: Need of facilities, slow, limited

2. Removal of solids in suspension. Sedimentation

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Advantages: Removes colloids, time, equipment

Disadvantages: Chemicals, factor control (temp. time, dosage)

2. Removal of solids in suspension. Flocculation

colloids coagulation

dosage and mixture

flocculation

sedimentation

polyelectrolyte

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Advantages: No chemicals, modules, possible sterilization

Disadvantages: Material (means of filtration) and facilities

AbsortionActive carbon

Filtration + Back washing

2. Removal of solids in suspension. Filtration

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3. Disinfection

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To destroy the germs present in the raw water

To destroy the germs introduced in the treatment and

distribution systems (pipeline and storage)

3. Disinfection: Aims

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Properties of disinfection agents

Physical agents: heat, UV radiation

Chemical agents: chlorine, ozone, iodine, salts of

ammonium…

Chlorination

Calcium hypochlorite HTH 70 % of active chlorine

3. Disinfection: Procedures

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3. Disinfection: Chlorination dosageR

esid

ua

l ch

lori

ne

mg

/l

Applied chlorine mg/l

Maximum quantity of combine chlorine

Break point

Free chlorine

Residual combine chlorine

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Dosage: Chlorine request test

Contact time

pH and temperature

Final ranges: 0.4 - 0,8 mg/l

Shock chlorine

3. Disinfection: Chlorination

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DIAGRAMME

INPUT TANK PREOXIDATION

CARBON FILTER

COAGULATIONFLOCCULATION

SEDIMENTATION

SILEX FILTER

FINAL CHLORINATION

OUTPUTDRINKING WATER

SLUDGE

DRINKING WATER

WASTE WATER

WASTE WATER

RAW WATER

COAGULANT

FLOCULANT

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4. Water treatment in emergencies

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Pumping water from the water source

Water storage in an onion tank (30,000 l.) Water pre-treatment

with flocculent

Submersible pump

WATER TREATMENT PLANT

Silex filterCarbon filterRapid mixer

Pressure group

Residual Chlorine

Bladder tanks (10,000 litres) to store drinking water

Water distribution

Water distribution: Taps

Chlorine & Alum

Flocculation tank

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• Specialized water production

FLOCCULATION – pre-treatment in the tank

– treatment in the sedimentation tank in the WTP

CHLORINATION – in the WTP (shock & residual)

4. Water treatment in emergencies

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4. Water treatment in emergencies

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• Mass water production

FLOCCULATION– in the tank as chlorination pre-tretament

CHLORINATION – in the tank

4. Water treatment in emergencies

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4. Water treatment in emergencies

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Thank youThank you……….……….