Water Treatment Filters

8/10/2019 Water Treatment Filters

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WATER TREATMENT`

Prepared by: Mahdi khalife 2865

Presented to: Dr. Bassam Ryachi



INTRODUTION

Water quality is not always suitable for

the numerous activities such as: drinking,

irrigation, industry…

Water should be treated before coming to

usage.

Many factors may affect the water quality.

Our concern in this research is the

potable water.



INTRODUTION

Water may be contaminated by many

sources of pollution such as: airports,

septic tanks, automobiles, industrialfacilities, mining operations, agricultural

application, watersheds…

The different sources of pollutionrequires a multi-stages treatment

process.



WATER TREATMENT STAGES

1. INTAKE

2. COAGULATION AND FLOCCULATION

3. SEDIMENTATION (SETTLING)

4. FILTRATION

5. DISINFECTION





1. INTAKE

The intake process is simply pumping the

water under treatment from its source to

the treatment station. The sources of water may be surface or

underground sources.



2. COAGULATION AND

FLOCCULATION

Some particles in water have the ability

to settle by themselves, while others are

not due to many reasons, such as theirsmall size or the existing charges…

The process of coagulation and

flocculation is necessary to remove suchobjects.



2. COAGULATION AND

FLOCCULATION

Types of objects in water:

1. Chemicals in solution, which are electrically charged,

dissolved and stable in water, so they don’t settle

automatically.

2. Colloidal solids, they are electrically charged but

they are not dissolved in water, these particles are very

small particles and they will not settle even in years.

3. Suspended solids, they are solids of larger diameterthan colloidal, they may settle alone if left in water for a

long time.



2. COAGULATION AND

FLOCCULATION

Particles in water tends usually to have a

negative charge, so they repel each other

and they will never settle.



2. COAGULATION AND

FLOCCULATION

Coagulant chemicals tend to have positive

charge to neutralize the charges to prevent the

repulsion.

The amount of the coagulant is determined

according the Zeta potential.



2. COAGULATION AND

FLOCCULATION

The Van der waal force causes the

neutral particles to attract each other.



2. COAGULATION AND

FLOCCULATION

When enough particles attract and join

each other they floc, i.e. form bigger

particles that may settle or may befiltered.



2. COAGULATION AND

FLOCCULATION

There are many used coagulants, but the

most commonly used are alum and ferric

sulfate.



3. SEDIMENTATION

Also called settling. It is the process of

lowering the velocity of water below the

suspension velocity so that thesuspended particles fall by gravity.

This process comes after the coagulation

and flocculation process. Or it may be atthe beginning of the treatment but not

very effective.



3. SEDIMENTATION

There are there common types of basins of

sedimentation:

1. Rectangular basin, it is composed of a large tank

where water flows horizontally. It is cheep and simplein design and low maintenance is needed, the risk of

short circuit is low. But it occupies a large area.



3. SEDIMENTATION

2. Double deck rectangular basin: are essentially two

rectangular sedimentation basins placed one above the

other. This type of basin conserves land area, but has

higher operation and maintenance costs than a one-

level rectangular basin.



3. SEDIMENTATION

3. Square or circular sedimentation basin: water flows

horizontally, they are also known as clarifiers. This

type of basin is likely to have short-circuiting

problems.



3. SEDIMENTATION

Four zones are observed during the

settling process. The inlet zone, the

settling zone, the sludge zone and theoutlet zone.



3. SEDIMENTATION

Inlet zone: the most important points in this zone is todistribute water and control velocity to prevent

turbulence.

Settling zone: it is a large expanse of water where

water velocity is reduced. Tube settlers increase the

settling efficiency.

Outlet zone: water speed should be also low, outlets

can control the level of water. Usually baffles are

installed to prevent floating materials from passing.

Sludge zone: the velocity should be extremely slow to

prevent re-suspension of settled solids. Sludge should

be disposed from the basin to increase the usable

volume of the tank.



4. FILTRATION

In this process more suspended particles

should be removed from water.

It the process that follows sedimentation. It is necessary to reduce the turbidity not

because turbidity is harmful by itself, but

because it harden the disinfectionprocess.



4. FILTRATION

Usually sand filters are used in the

filtration process.

Some chemicals called polymer aid mayhelp to catch the flocs.

Four mechanisms are observed in the

filtration process: straining, adsorption,biological action and absorption.



4. FILTRATION

Straining: it is passing the water through

a medium where pores are smaller than

the flocs, so they can be captured. Sand is good for such application.



4. FILTRATION

Adsorption: it is of the most important

mechanisms, composed of gathering

gas, liquid or solid particles on thesurface of another material. And very

small particles in the water can stick to

the sand particles.



4. FILTRATION

Biological action: it involves the

breakdown of particles in water by

biological action. This may involvedecomposition of organic particles by

algae, plankton, diatoms, and bacteria or

it may involve microorganisms eatingeach other.



4. FILTRATION

Absorption: it is the process of soaking

up of a substance in another body. And

here liquid is absorbed by sand grain.This is not an important mechanism in

the filtration.



4. FILTRATION

Main types of filters and some of there

properties are shown in the following

table:TYPES OF FILTERS







http://localhost/var/www/apps/conversion/tmp/scratch_4/types%20of%20filters.doc








4. FILTRATION

Some filters require backwashing process such

as the sand filters. The process is composed of

reversing the direction of water and increasing

the velocity to cause the suspension of sand

and flocs and remove the infiltrates from the

sand.



4. FILTRATION

Some filters might include many media which

increase its efficiency and its capability to

remove many types of dirts.

Media are arranged successively according to

decreasing pores.



5. DISINFECTOIN

In this process, pathogens must be killed or

removed to ensure that the drinking water

doesn’t contain any disease agent.

Sedimentation and filtration removes some

bacteria from water by physical manner.

Disinfection is usually killing or inacativating

bacteria by chemical means.



5. DISINFECTOIN

Chlorination is the most common

disinfection method in water treatment.

But it may holds some disadvantages towater like making an odor or taste, of

reducing iron and magnesium contained

in water.

Chlorination is also beneficial in

coagulation.



5. DISINFECTOIN

Of the reactions that takes place when

chlorine is added:

Cl2 + H2O HOCl + HCl HOCl is effective in killing the bacteria.

The pH of water will control the amount of

formation of HCl.

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Water Treatment Filters