WEEK FIVE
SUBJECT: BASIC SCIENCE
CLASS: GRADE 7
TERM: SECOND
TOPIC: DISEASE
PREVENTION
WATER-SOURCES: There
are various sources of water which include;
PIPE-BORN WATER: This
is improved water quality that’s not exposed to contaminants en-route or
through surface runoff and is usually transported through a pipe. It is prepared by filtration followed
by chemical treatment of water. It is also free from bacteria but may contain
essential mineral solutes.
SPRING WATER: A
spring is a point of exit at which ground water from an aquifer flows out on
top of Earth’s crust and becomes surface water. It is a component of the
hydrosphere. Springs have long been important for humans as a source of fresh
water, especially in arid region which have relatively little annual rainfall.
WELL WATER: Well
water is untreated ground water stored in aquifers (underground layers of
porous rock). Wells get drilled as far
down as 1000 feet into the rock to access the water. Pipe casing gets installed
into the hole, and a concrete or clay sealant surrounds it to protect against
contaminations.
PROCESSES/METHODS OF WATER
TREATMENT/PURIFICATION:
Coagulation: This
is often the first step in water treatment. During coagulation, chemicals with
a positive charge are added to the water. The positive charge neutralizes the
negative charge of dirt and other dissolved particles in the water. When this
occurs, the particles bind with the chemicals to form slightly larger
particles. Common chemicals used in this step include specific types of salts
or alums, aluminum or iron.
Flocculation: Flocculation
follows the coagulation step. Flocculation is the gentle mixing of the water to
form larger, heavier particles called flocs. Often, water treatment plants will
add additional chemicals during this step to help the flocs form.
Sedimentation: Sedimentation
is one of the steps water treatment plants use to separate out solids from the
water. During sedimentation, flocs settle to the bottom of the water because
they are heavier than water.
Filtration: Once
the flocs have settled to the bottom of the water, the clear water on top is
filtered to separate additional solids from the water. During filtration, the
clear water passes through filters that have different pore sizes and are made
of different materials (such as sand, gravel and charcoal). These filters
remove dissolved particles and germs, such as dust, chemicals, parasites,
bacteria and viruses. Activated carbon filters also remove any bad odors.
WATER-BORN DISEASES:
These are diseases that are spread through water medium. They include cholera,
diarrhea, typhoid, dysentery, etc.
Cholera: Cholera
is an acute diarrhoeal infection caused by eating or drinking water that is
contaminated with the bacterium vibrio cholera. Cholera is an extremely serious
disease that can cause severe acute watery diarrhea with severe dehydration. It
takes between 12 hours and 5 days for a person to show symptoms after consuming
contaminated food or water. Cholera affects both children and adult and can
kill within hours if untreated.
Typhoid fever: Typhoid
fever is a bacterial infection that can spread throughout the body, affecting
many organs. Without treatment, it can cause serious complications and can be
fatal. It’s caused by a bacterium called Salmonella typhi, which is related to
the bacteria that cause salmonella food poisoning.
ASSIGNMENT
OBJECTIVE QUESTIONS:
1.
Which of the following is NOT a method of purifying water? A. Addition of alum
B. Boiling C. Chlorination D. Filtering
2.
The following are natural sources of water except A. ocean B. pipe borne C.
rain D. spring
3.
Water borne diseases include the following EXCEPT A. cholera B. diarrhea C.
dysentery D. measles
4.
Which of these diseases can be contracted through impure drinking water? A.
measles B. scabies C. tuberculosis D. typhoid fever
5.
Which of the following is not a process of water purification? A. Coagulation
B. Flocculation C. Sedimentation D. Solution
6.
During sedimentation, flocs settle to the bottom of the water because A. they
are heavier than water B. they are lighter than water C. they are heavier than
air D. they are lighter than air
THEORY QUESTIONS:
1.
List and explain three sources of water.
2.
Explain the processes of water purification.
3.
List four water born diseases and explain two.
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