EO 011.02; Inspect Water Distribution TP's 1-2 - CFHSTC

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Feb 21, 2014 (3 years and 4 months ago)

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QL5A Preventive Medicine



EO 011.02



INSPECT WATER
DISTRIBUTION

(Engineered Water Purification)




Engineered Water Purification




TP1

REFERENCES



CFP 213


Public Health and Preventive Medicine, 14
th

Edition, Maxcy
-
Rosenau


Osmotics Pure Water Handbook, 2nd Edition


Engineered Water Purification


Introduction


The various processes which are applied in order

to render a water supply potable are referred to as

treatment


Engineered Water Purification


Objectives in treatment

Treatment Processes

Aeration

Sedimentation (clarification)

Coagulation

Coagulants

Coagulant Dosage

Filtration

Disinfection

Engineered Water Purification



Typical Water Treatment Plant Profile



Refer to figure 37
-
3 in the reference of
Maxcy
-
Roseneau

Engineered Water Purification


Coagulation:


Colloidal and suspended particles are brought together

to form large
flocs

that are settle more easily. This

occurs in nature in lakes and other bodies of water, but

it is an important process in water purification and is

aided by the addition of coagulants such as alum

(aluminum sulphates) or synthetic polymers.




The
floc

is then removed by

sedimentation, filtration, or both.

Engineered Water Purification


Engineered Water Purification


Sedimentation:


Under the action of gravity, particulates,
including bacteria, settle to the bottom.
Because the settling velocities of these samll
particles are low, turbulence or swift currents
interfere with sedimentation so that the
process is effective only in slow
-
moving
bodies of water such as lakes.



In engineered works, special tanks that

minimize extraneous currents are used ,

encouraging the settling of the smallest

and most dense particles. Coagulation

assists in sedimentation


Engineered Water Purification


Engineered Water Purification


Management of Sludge:




The material that falls to the bottom of

the tank,
sludge
, is now identical as a

residual to encourage its recovery as a

by
-
product of the treatment process.




At one time this sludge was returned to the
river whence the raw water was drawn.
Transport by truck to a landfill or other
acceptable place for disposal may be
required.

Engineered Water Purification





Questions

Inspect Water Distribution




Filtration




TP2

REFERENCES



CFP 213


Osmotics Pure Water Handbook, second
edition


Public Health and Preventive Medicine, 14
th

Edition, Maxcy
-
Rosenau


Inspect Water Distributions

Filtration:


1.
Slow sand;

2.
Rapid sand;

3.
Pressure; and

4.
Diatomaceous earth.



TP2

Slow Sand


Water percolates by gravity


Filtration is slow and large surface area
required


Used in small communities


Forms Zoogleal layer. This layer eventually
retards the flow of water


This layer must be periodically scrapped off;


This scraping necessitates the periodic
replacement of sand.


Slow Sand Filtration









Slow Sand Filtration


Rapid Sand Filters


Rapid sand filtration is contrasted to
slow
sand
filtration

by increased flow rate and
method of cleaning the filter bed.



Rapid sand filters are cleaned often, usually
daily, by reversing the flow of water through
the entire filter bed, referred to as
backwashing.



Slow sand filters are cleaned less frequently
by removal of the top layer of media.

Rapid Sand Filter

Pressure Filters


Filter bed and underdraines are placed in an
enclosed vertical or horizontal steel cylinder


Water is forced under pressure


Commonly used in swimming pools


Cleaning pressure filters is accomplished by
backwashing

Vertical and Horizontal Pressure
Filters


Diatomaceous Earth


Water is pumped under pressure from the
bottom and out of the top.


ERDLATOR






Charcoal


Also known as Activated carbob


Absorbs many dissolved organics and
eliminates chlorine.


It does not remove salts.


Charcoal can become breeding ground for
bacteria


Changed frequently

Water Treatment Methods


Water treatment can be defined as any
procedure or method used to alter the
composition or “behaviour” of a water
supply.


Membrane Technology
Applications

Membrane Tech Apps…Cont


Reverse Osmosis (RO)


Electodialysis (ED)


Microfiltration (MF)


Ultra filtration (UF)

Reverse Osmosis


(RO)
was the first cross flow membrane
separation process to be widely
commercialized.


removes most organic compounds and up to
99% of all ions


More energy efficient than distillation

Electrodialysis


Elecrical current is employed to specially
-
prepared membranes


These membranes are semi
-
permeable


Reduces the ionic content of the water

Mircofiltration (MF)


MF


membrane filters typically rated in the
0.1


3.0 micron range

Ultrafiltration (UF)


UF removes larger organics, colloids,
bacteria, and pyrogens while allowing most
ions and small organics such as sucrose to
permeate the porous structure.


UF range: 0.005
-

to 0.15
-
micron.

Questions