Shore intake is
used in shallow narrow & navigable rivers or waterways. They are
constructed on the shore with the necessary parts for entrance of water and
retaining walls. Shore intakes may be suitable for industrial plants where
water quality is not of primary consideration or for public water supplies
where water quality and other conditions permit
· PRESSURE CONDUITS
Are those in
which the water flows under hydraulic pressure these include pipelines of such
materials as cast iron, steel, ductile, reinforced concrete, asbestos cement
etc.
The
type of conduit to be selected depends on such factors as topography type of
soil to volume of water to be carried and comparative costs A velocity of 0.8
to, 1.2 meter per second in the intake conduit will give satisfactory
performance.
LOW LIFT PUMP
It is
preferably located as near as possible to the intake structure and the
following conditions must be fulfilled :
One the size of
the building should be sufficient for the erection of the total number of pumps
including the pumps, which will be needed for future use.
Two- the
building should be beautiful and from the engineering point of view in order to
increase the credit of people about the water supply works in their city.
Three the pipe
lines and electric cables inside the building should be located in places,
where easy maintenance and operation are available.
The function of
the low lift pumps is to raise water from its level in the adjoined raw water
pump up to the manometric head of these pumps do not exceed 10 ms and that is
why it is called low lift pumps .
· DESIGN DISCHARGE OF LOW LIFT PUMP
The design flow
of the low lift pumps depends mainly on :
One – the
population served by the project.
Two- average
annual consumption.
Three- the
variation from this average.
Four – the
capacity of the filtered water reservoir
Five- the
number of working hours of the low lift pumps per day sometimes is less than 24
hours.
In case of
decreasing the storage capacity of the filtered water reservoirs, the design
discharge should be increased to meet the variations of the rate of
consumption. In case of canceling the reservoirs, the design discharge reaches
its optimum value, which derh is determined by the peak demand load and this
rarely happens. It is always preferable to consider the design discharge for
the low lift pumps as the maximum monthly consumption, but additional reserve units
should be taken into account as stand – by and under preparing units.
In such a case
the design of the filtered water reservoits should meet the daily change and on
the current of one day (from hour to hour at the same day) .
INGRUSTATION OF SCREENS
Incrustation
may be caused by the direct deposition of suspend matter from the water on the
screen, by the release of dissolved minerals from solution due either to change
in pressure at the screen or to chemical reaches, and to biological activities
resulting in the deposition of gelatinous material on the screen.
The principal
incrustant is calcium carbonate, which both forms a scale on the screen and
cements depose particles. Wells are acidized or chlorinated for the purpose of
dissolving or dislodging clogging material or incrustation on the screen or in
the sand around the screen. Acids may be used only where the metal of the
screen will not be attached by them
Brass or bronze
may be treated with muriatic acid, HCL..while iron requires nitric acid.
Chlorine has been added to wells remove sincrustants resulting from the
activities of the So- called iron bacteria.
· PUMPING EQUIPMENT FOR WELLS
Many type
of well pumps are on the market to suit the wide variety of capacity
requirements depths to water and sources of power domestic systems commonly
employ one of the following pumps:
- for lifts under 10ms:
a small reciprocating or piston pump
-
for lifts up to 50ms :
A centrifugal pimp to which water is lifted by
recalculating part of the discharge to a jet or ejector
-
for lifts that cannot be managed by jet
pumps:
Installed in the well and driven by pump rods
through a jack mounted the well head large capacity system is normally equipped
with centrifugal or turbine pumps driven by electric motor. A sufficient number
of pump bowls are connected in series to provide the necessary to overcome
static heads at lowest levels.
Pump
installation with submersible pumps above and below floor and pumps
installation with borehole pumps-hollow shaft motor
Physical & chemical and bacteriological
imparities in water their causes and effect
Some desirable and
undesirable constituente of water for various purposes are listed the amounts
stated are in parts per million p.p.m they are to be taken as suggestive only.
Table Desirable
and undesirable mineral matter in water
Hardness p.p.m.
|
0-55
|
56-100
|
101-200
|
201-500
|
Degree of hardness
|
Soft
|
Slightly
|
Hard
|
Very hard
|
The effect of hardness in water is the
prevention of lathering by soap and the formation of scales in boilers
ALKALINTY OF
WATER
Alkalinity of natural water represents its
contents of carbonates bicarbonates and hydroxides caustic alkalinity caused by
hydroxides is an undesirable characteristic seldom found in natural water.
CHLORIDES IN
WATER
chlorides are present in natural water mainly
as salts of sodium may indicate pollution by certain industrial wastes.
IRON AND
MANGANESE IN WATER
they are objectionable in public water supply
because they cause stains on plumbing fixtures and on clothes, they may cause
tastes and odors and they offer difficulties to some manufacturing process. The
presence of iron is common in ground water, resulting from contact of water
coal and iron ores.
Manganese behaves similarly to iron in
its reactions in natural water in general, the maximum concentration of iron or
of manganese or the combination of iron and manganese, which is permissible in
a water supply is about 0.2 to 0.55 p.p.m.
LEAD AND
COPPER IN WATER
Lead is considered undesirable in water
because of its tendency to accumulate in the human body, resulting in lead
poisoning. The amount of leas and copper found in natural water are negligible.
However, water flowing through or standing in conduits or reservoirs containing
these materials may absorb traces of these metals. Maximum concentration of
lead permitted is 0.1 p.p.m. Concentrations greater than 0.3 p.p.m. Of copper
are undesirable.
CARBON
DIOXIDS IN WATER
The concentration of carbon dixide is of
importance in a water supply because of
(One) the
desirable taste that it imparts to water
(Two) its
effect in increasing the solubility of many minerals water
(Three) the
corrosiveness of water from its presence
ORGANIC LIFT
IN WATER
living organisms can be divided into three classes
according to their size, as macroscopic, microscopic, and bacteria.
Macroscopic
organisms are so large that they can be distinguished by the eye, e.g. fish.
Microscopic organisms are small so that the aid of microscope is necessary to
see them. Bacteria are so small that even the aid of microscope is
insufficient. They can only be identified by their reaction to certain media,
natural waters, particularly surface waters, contain various kinds of organic
life.
BACTERIA IN WATER
Bacteria are on cell organisms of size varing
from 60 to 0.3 u.(one u , called a micron , I.e. 1/10,00 cm ) these bacteria
which cause diseases to man are know as pathogenic. Practically all-pathogenic
bacteria which cause diseases to man are know as pathogenic. Practically all
pathogenic bacteria that can be born by water are related to the intestinal
tract of warm blooded animals, particularly man. Water- borne pathogenic
bacteria will not multiply in natural water, also their isolation
identification is difficult by laboratory means. There is, however, a harmless
bacteria, know, as escherichis coil, that is relatively easily isolated and
identified the presence of this organism in a sample of water is taken to
Indic. The presence of fecal matter in the water and is a warning that
pathogenic bacteria may also be present. Hence, upon the presence or absence of
the E. coli is often based the option of the safety of the safety of water for
drinking purposes. Main diseases caused by water- borne organisms are typhoid
fever, cholera, dysentery and amaebic
Dysentery.
MICROSCOPIC
ORGANISMS
Microscopic organisms are found principally
in surface waters e.g. fungi. The principal objection to the presence of
microscopic organisms in a public water supply are the tastes and odors they
produce.
MACROSCOPIC
ORGANISMS
the macroscopic organisms most commonly
causing difficulties in natural water include cattails eel grass and dea weeds.
Non of these organisms is desirable in water supply sources. But they are
difficult to remove. Tastes, odors, and color caused by them may be removed in
the process of purification macroscopic animals include fish, worms and
insects.
TOXIC
SUBSTANCES, HEAVY METALS RADIOACTIVE SUBSTANCES AND ORGANIC MICRO POLLUTANTS
most of
these substances are toxic or of harmful effect as they are accumulated in the
human body.
THE
REQUIREMENTS OF WATER QUALITY
In the option of those who are familiae with
the developments of water supply standards, the following may be guide for the
requirements of water quality:
HYGENIC
PROPERTIES
The water must be free from pathogenic or
disease producing organisms. This condition of safety must prevail continually
and the supply must not be subjected to what may be termed “ accidental”
contamination.
ESSETIC
PROPERTIES
One water should be sparkling clear
and colourless (not turbid neither form inorganic nor organic materials)
Two – water
should be free from objectionable gases, iron and manganese.
Three- water
should be neither corrosive nor scale forming.
Four – water
should be plentiful and low in cost.
CLASSIFICATION
OF WATER:
CLEAN WATER
This should be safe for human consumption as
determined by lab tests, sanitary survey and continued use. It should be
attractive and appealing to the human sense of odour and taste.
POLLUTED
WATER
This is water
that has suffered impairment of physical qualities through the addition of
substances causing turbidity, color, odor or taste.
CONTAINATED
WATER
This is water that carries potential
infection by reason of the polluted and contaminated and therefor
unsatisfactory for human consumption until properly treated.
SOURCES OF
POLLUTION
One - some municipalities discharge sewage
into a water source that is used as a public water supply for some other cities
this is perhaps the most dangerous source of contamination.
Two – soil washing may carry leaves
mud, decayed vegetation, human and animal refuse into the water supply, thus
rendering it turbid and unclean in appearances. The turbidity of muddiness and
mineral contents of water in a stream vary from day to day following heavy rain
streams are often extremely muddy and low in mineral content, while during dry
seasons, it may be relatively clear and more highly mineralized organic matter
such as decayed leaves and vegetation and wastes furnish food for micro
organisms such as algae and lower forms of animals life. These micro- organisms
may impose to the water disagreeable taste and odour.
Three – industrial wastes
discharges into streams may be
objectionable because they are acid in nature, in which case they render the
water unfit for use, or too corrosive for distribution through the ordinary
cast iron pips, industrial wastes also may cotain excessive organic matter
which after decomposition cause the water to be unpalatable.
Four- subsoil filtration into streams
of water from mannered land on banks.
Five – washing of clothes and bathing
of man and animal in canlas and streams.
Six – throwing of dead bodies into
rivers and streams. A dead animal is not so dangerous as a human body, because
the formers dose not necessarily harber bacteria that are pathogenic to man.
Seven - navigation, this can be
divided into two parts:
· Moving
Boats
Pollution is brought about through the sailers and
passengers wastes the problem become moreserious within the boundaries of the
cities because of the forced stay of several hours waiting for bridges to open.
This problem is clear in Alexandria where it may take days for a bout to pass
through the numerous mahmoudia canal bridges.
·
stationary boats
As in Cairo
this boats spread being inside the city may causes excessive pollution and
spread into the river water seeds of typhoid dysentery and other disease.
For all the above reason,
river, canal, lakes water should go through comprehensive purification works
before its use by the public.
SELF –
PURIFICATION OF STREAMS
There is a popular motion that streams purify
themselves since there are natural processes that to lessen the impurities in
contaminated streams, lakes and reservoirs. The study of the various factors
contributing to the self- purification of streams has been lead into dividing
them in 3 main parts:
PHYSICAL
FACTORS
One – settling:
Unless the velocity of flow is too great mud and suspended matter
naturally settle out of suspension sweeping with them vast numbers of bacteria.
Two – Dilution
This means that the polluting substances get diluted by means of water
in river and canal and their danger, thus becoming less in concentration and
the chances of infection through the polluted water is diminished.
Three –
sunlight:
Sunlight has come germicidal effect
due to its ultraviolet rays but it penetrates only a little below the water
surface and is not constant in action because at night and on some days the sun
dose not shine at all. Also this action depend upon the strength of the rays,
dust and humidity in the atmosphere reduce the amount of rays reaching the
surface of the earth.
CHEMICAL
FACTORS
oxygenation is the main purifying chemical
action, there are two sources of oxygen in rivers and canals, those are :
One –
Atinospheric oxygen:
(Absorbed by the water from atmosphere) this
is accomplished more quickly and effectively if the stream passes over rough
beds cascades.
Two- the
oxygen given off by aquatic plants:
The plants ( like all others ) under the
effect of sun rays break down co2 in the water by photosynthesis
giving off oxygen which is used in the oxygenation process. It should be noted
that this oxygenation process is accomplished through the activity of certain
types of bacteria.
BIOLOGICAL
FACTORS
the bacteria in the water are mostly derived
from the bodies of man and the removal from their natural habitat and food
supply naturally turns them down and exposes them to unfavorable environment
under which it is not possible for them to multiply, i.e, the exposure of
bacteria to other organisms present in the water would materially hasten
purification process.
POTABLE
WATER STANDARDS
Table gives details of the world
health organization
(W.H.O)
Standard for drinking water. It is followed in Egypt without much variations