مياه الشرب (مشاكلها-علاقتها بالامراض الوبائية-كيفية معالجتها)

Potable Water

BY

GENERAL.DR

BAHAA BADR

TECHNOLAB EL-BAHAA GROUP

The Centers for Disease Control and Prevention's Vessel Sanitation Program is proud to
bring to you the following session: Potable Water.

While this presentation is primarily
intended for cruise vessels under the jurisdiction of the Vessel Sanitation Program, it may
also be used by anyone who is interested in this topic.

This session should not be used as
a replacement for existing interactive training, but should be used as an adjunct to a
comprehensive training program. Potable water.

Learning objectives.

Our learning objectives in this session will be to list pathogens that
can cause waterborne illness, list the common deficiencies in drinking water systems that
can cause waterborne illnesses, list the free halogen residuals required for production

and

distribution, list the information required during documentation of maintenance, cleaning,
and disinfection of potable water tanks, list the requirements for manual monitoring
should the far point analyzer recorder fail.

Potable water illnesses. England. In Soho, England, in 1854,

there was a large cholera
outbreak resulting in over 10,000 people dead.

This outbreak occurred at a well on Broad
Street in this community. Dr. John Snow lived there at the time, and noticed that the
incidents of the disease amongst the population occurred from the people drinking from
this particular well.

Although he couldn't get the town fathers to stop utilizing the well, he
did get them to remove the pump handle, which decreased the incidents of cholera in that
area.

Pennsylvania. In 1885, in Plymouth, Pennsylvania, there was a large typhoid outbreak
resulting in 1,000 people becoming ill. The town was low on water during this
wintertime, and they would run pipes into the river to pump water up to fill the reservoirs.

Unbeknownst to the people of the community of Plymouth, in a small community called
WilkesBarre
just north upstream of Plymouth, the people dumped their raw sewage into
the river.

The town fathers were literally pumping raw sewage up into the water system in
Plymouth.

As we can see from this slide, the rates for typhoid fever were very high prior to 1908.

In
1908, chlorination of public drinking water systems was begun in the United States.

After
that, as we can see from the slide, the rates of typhoid fever dropped dramatically.

Missouri. Cabool, Missouri. In 1989 there was a large outbreak of gastrointestinal illness
caused by E. coli 0157:H7. There were 243 cases, 32 hospitalizations, and four deaths.

This outbreak was the result of E. coli contamination of the wells in the town of Cabool.

This city was not chlorinating their water at the time.

Wisconsin. In 1996 there was a large cryptosporidium outbreak in Milwaukee,
Wisconsin, population 800,000. 370,000 people became ill, with 4,400 people
hospitalized and approximately 40 deaths.

This outbreak occurred due to a surface water
system that the city pulled from. During heavy rains, the surface water treatment system
became overwhelmed, and cryptosporidiumosis broke through and contaminated the
entire water system throughout the city.

Alabama. In 1992 there was a large outbreak of Vibreo cholera associated with seafood
in Mobile, Alabama.

This outbreak was traced back to tankers dumping ballast water
from water they had originated from South America.

Waterborne illnesses. Routes of exposure include ingestion, respiration, and contact.

Pathogen types of concern are bacteria, viruses, and protozoa.

Pathogens and water. Some of the pathogens we're concerned about in drinking water are
shigella species, giardia, cryptopsporidium, Vibeo cholera, Escherichia coli, and
legionella.

Cryptosporidium parvum. Cryptosporidium parvum is a coccidian protozoa.

The
reservoir is humans, cattle, and other domestic animals. Water treatment optimization
includes sedimentation, coagulation, and filtration.

Filtration is required at the 0.1 to one
micron level. Boiling water for one minute will eliminate the oocyst.

Vibreo cholera is a bacterial illness. Humans are the reservoir, and disinfection with
chlorine is very effective.

Eschericia coli, or E. coli. Two important strains are enterohemorrhagic and
enteroinvasive. Several important pathogenic strains based on serology and virulence
exist.

Eschericia coli, EHEC. This is E. coli 0157:H7. Cattle are the primary reservoir for this
E. coli. Chlorination of water is an effective treatment.

Eschericia coli, not EHEC. The infectious dose is ten to the eighth to ten to the tenth
organisms.

Humans are the primary reservoir of this E. coli. Again, chlorination is an
effective treatment for water.

Waterborne illness associated with drinking water by etiologic agent, United States,
19992000.

As we can see from this slide, a little more than 50% of the outbreaks in the
United States during this time period were related to parasitic, bacterial, and viral
organisms.

As we can see from this slide, more than 80% of the waterborne illnesses were
associated with untreated groundwater, a treatment deficiency, a distribution system
deficiency, or an untreated surface water source.

Potable water. We're going to discuss the importance of potable water, water sources,
water storage, water distribution, and bacteriological testing or monitoring.

Potable water sources. Bunkered water or water loaded from shoreside, production water
which includes evaporators and reverse osmosis units, or RO units.

Bunkered water. Bunkered water can come from many different sources.

You may have
groundwater, surface water, mixed groundwater and surface water sources, or
desalinization plants.

Bunkered water.

The minimum requirement for bunkered water is it
must meet world health organization drinking water quality standards.

You must have a
recent water quality report onboard the vessel. Bunkered water.

The advantages of
bunkered water are large quantities. The disadvantages are variable quality and cost.

Potable water filling. Bunker hoses. We're going to discuss storage, handling, connection
procedures, and labeling.

Hose storage. Hoses should be used for no other purpose. They should be drained after
use, they should be rolled up or placed on a hose reel, and they should be capped or
coupled together to prevent contamination. Hose storage.

A cabinet or locker should be
provided for hose storage.

The material the locker is constructed of should be durable.

The locker or cabinet should be labeled, it should be easy to clean, it should be selfdraining,
and it should be elevated off the deck at least 45 centimeters or 18 inches.

Handling.

Hoses should be handled in a sanitary manner.

They should not be placed in
the harbor or in standing water, and do not drag the hose ends on the deck. Connection
procedures recommended.

Sanitize the connections utilizing 100 milligrams per liter of
chlorine. Flush the shoreside connection to waste.

Connect the hose or hoses to the shore
side.

Flush the hose to waste, then connect to the vessel. Potable water hose labeling.
Each connection into the hose should be labeled "potable water only.
"
Production water.

The advantages of production water are consistent quality, unlimited
supply, and low cost.

Disadvantages of production water include you may operate at sea
only, and you may have quantities limited by your production capacity.

Reverse osmosis.

Reverse osmosis works by pressurizing the high saline water and
pushing the liquid through a membrane, resulting in a potable water product.

Producing water in port.

This is allowed only if the system cannot produce potable water.

It must be completely separate from the potable water system.

Treatment of bunkered production water. Production water must be halogenated to two
parts per million.

Halogen level must be tested and recorded every four hours.

Bunkered
water must be halogenated to two parts per million.

Halogen level must be tested and
recorded every hour.

Potable water storage. Storage facilities. Tanks must be labeled "potable water."

Tank
coatings must be approved and documentation must be available on the vessel for the
tank coatings and the manufacturer's procedures for applying and curing those coatings.

Tanks must have a sample point which is turned down, and there must be a sanitary water
depth determination method. Events and overflows must be protected.

Potable water tank maintenance. Tanks must be inspected every two years or every dry
dock, whichever is less.

Detailed records must be maintained on the vessel recording the
type of maintenance performed, the cleaning procedures, and disinfection, including the
residual, the contact time, and the flushing or dechlorination to less than five parts per
million.

Water distribition system, water disinfection. Water disinfection methods. Methods
include boiling, ultraviolet light, ozone, or halogenation.

Water disinfection, ultraviolet light. Advantages of ultraviolet light include no taste or
odor and no byproducts.

The disadvantage is there are no measurable residuals to protect
the water system after the initial ultraviolet light treatment.

Water disinfection, ozone. Advantages include no taste or odor, and no byproducts.

Again, the disadvantage is no measurable residual to protect the water system after the
initial treatment.

Water disinfection, halogenation of chlorine and bromine. Advantages
of disinfecting with chlorine or bromine include available residual, easy to test for, and an
inexpensive test.

Disadvantages include taste and odor and byproduct formation.
Water treatment. In the following slides we'll discuss the addition of chlorine to treat the
water.

As we can see in this water droplet, we have added chlorine to treat pathogens.

As
the chlorine sits in contact, it starts combining with pathogens and removing them.

Some
pathogens are slightly more resistant, and take a longer contact time.

But as the time
passes, the chlorine effectively removes all of the pathogens.

Free available chlorine.
After the chlorine has been in contact with the water for some time, all the pathogens
have been destroyed, and we have a residual left called free available chlorine which is
available to protect the water system should it become contaminated later on.

Chlorine mechanics.

How does chlorine kill microorganisms?

This slide shows how
chlorine is effective against different types of microorganisms.

To the left, on the vertical
side, represents chlorine effectiveness from lowest to highest, bacteria being most easily
destroyed by chlorine.

In bacteria, the chlorine penetrates the cell wall and kills the
organism. With viruses, which are not a living organism, the chlorine attaches to the virus
and inactivates it.

Giardia. Chlorine also inactivates this organism.

Cryptosporidium is
resistant to chlorine in levels seen in drinking water systems.

Used alone, chlorine would
have no effect on cryptosporidium.

Chlorination mechanics.

Chlorine treatment standards, C times T, T being the time water
is in contact with the chlorine and C representing the concentration of the free chlorine in
milligrams per liter measured after a given amount of time.

Chlorination mechanics.

The
fraction of microbes killed increases linearly with the disinfection concentration or the
disinfection contact time.

Therefore concentration can be traded for time, as in the
example below.

Five parts per million times 100 minutes is the same as 20 parts per
million for 25 minutes.

Bottom line, disinfectant plus microbe equals dead microbe.

Halogen level requirements. Halogen level must be measured at the far point in the
distribution system, and the level must be maintained between 0.2 and five milligrams
per liter or parts per million.

Treatment system. We're going to discuss halogen injection and monitoring.

Halogen
injection system. The system must be automatic with a backup system, and it must be
analyzer controlled. You may use manual halogen injection in emergencies only.

Monitoring system.

The monitoring system includes the halogen analyzer and the chart
recorder. Free halogen analyzer.

The free halogen analyzer must be located at a far point,
the equipment must be accurate to plus or minus 0.2 milligrams per liter or parts per
million, the system must be calibrated or checked daily, and those calibrations recorded
in a log or on the charts.

The free halogen analyzer must have a low halogen level alarm.
This alarm must be audible and located in a continuously occupied location.

Chart recorder.

The chart recorder range must be 0.0 to five milligrams per liter or parts
per million.

The chart must be dated, reviewed, and initialed, and changed every 24
hours.

This is an example of a chart from a chart recorder.

Manual monitoring.

If the automatic system fails, you're allowed to do manual
monitoring.

However, readings must be recorded every four hours.

Manual monitoring
can only be done for ten consecutive days maximum before the equipment must be
repaired.

The manual monitorings must be recorded. They can be recorded on the charts
or in a separate log.

Microbiological testing.

Requirements. Analyze for E. coli (fecal coliforms).

Four
samples must be taken a month from the distribution system.

These samples should be
taken at different points of the distribution system and rotated monthly, and a followup
on positive tests must be done.

Analysis.

The microbiological analysis must meet
standard methods for the examination of water and wastewater.
ntation tube.