Water Chemistry
There are
three generalized areas of water involvement: 1)
Oilfield Water, 2)
Wastewater, and 3) Potable water. A computer program has been
developed for a certain aspect of Wastewater treatment. The
computer screenshot is viewed at the bottom of this page.
Potable Water
(Waste
Water is after this section. Scroll down for more information)
Potable
water is commonly known as 'municipal water' or 'drinking water' that
comes out of your faucet at home. Water from rivers and lakes are
treated with various chemicals to make it clear and healthy to drink.
Common terms
for treating water are: Flocculation, Chlorination, Fluorination, Taste
and Odour Removal and Filtration.
This
specialized area of chemistry employs many chemists and chemical
technologists. Potable water typically meets criteria defined by
test methods distributed by the
American Water Works Association (AWWA), American Public Health
Association (APHA), and the Water Environment Federation (WEF).
High standards are in place to ensure that public safety is the first
priority. Almost all required test methods are available and can
be found when searching the internet for 'Standard Methods for the
Examination of Water and Wastewater'.
Further
branches of this area ensure a high quality of supply of treatment
chemicals and products. Similarly, this is another area where
chemists and chemical technologists are employed.
A typical
potable water treatment plant will have the following treatment steps:
A) Water intake from the
middle-centre of a river stream
B) Bulk filtration
C) Flocculation
D) Rapid mixing
E) Settling
F) Decanting
G) Microbe neutralization
H) Fine filtration
I) Fluorination
Description of steps
A) Water intake from the
middle-centre of a river stream
When water is removed from
the middle (equal distance from each bank) and the centre (equal
distance from the river bottom and top), it is typically the cleanest.
Cleaner water requires less treatment (time and chemical) than dirty
water.
B) Bulk filtration
It is here that the large
debris is removed from the water. Debris usually consists of
trees, rocks and other undesirables.
C) Flocculation
Flocculants remove the fine
dirt and other materials that gives drinking water its clear, colourless
appearance. Flocculants attach themselves to many dirt particles,
which increases their mass.
D) Rapid mixing
This necessary step is
needed to facilitate equal distribution of the flocculent in the water.
E) Settling
After the rapid mixing step
is complete, the water forms large flocs, which drift to the bottom of
the settling pond.
F) Decanting
The clear water on top, is
removed from the settled flocs, which are now called sludge.
G) Microbe neutralization
Although the water has a
pleasant clear, colourless appearance, it may not be safe to drink due
to the microorganisms present. A biocide such as chlorine is added
to neutralize the organisms.
H) Fine filtration
Fine filtration uses other
chemicals to remove the organisms, taste, odour, and fine particulates
from the water. The water is ready to drink at this stage.
I) Fluorination
Some municipalities add a
small amount of fluoride to promote healthy teeth and bone formation.
Many successful variations
of these steps exist for each treatment operation. A general
rule-of-thumb is that each person in a town or city will use 650 litres per day.
Waste Water
Waste Water
is commonly known as Sewage water, disturbed water, or
process water that has been contaminated with some form of material
(sewage, dirt, sand, or other undesirable material)
Common terms
for treating water are: Flocculation, organic neutralization,
Biological Oxygen Demand (BOD) loading, Total Suspended Solids (TSS),
Total Dissolved Solids (TDS), and many other parameters defined by
municipalities and other regulatory bodies such as the Department of
Fisheries and Oceans (DFO).
This
specialized area of chemistry employs many chemists and chemical
technologists. Potable water typically meets criteria defined by
test methods distributed by the
American Water Works Association (AWWA), American Public Health
Association (APHA), and the Water Environment Federation (WEF).
High standards are in place to ensure that public safety is the first
priority. Almost all required test methods are available and can
be found when searching the internet for 'Standard Methods for the
Examination of Water and Wastewater'.
Further
branches of this area ensure a high quality of supply of treatment
chemicals and products. Similarly, this is another area where
chemists and chemical technologists are employed.
A typical
waste water treatment plant will have the following treatment steps:
A) Water Collection
B) Bulk filtration
C) Flocculation
D) Rapid mixing
E) Settling
F) Decanting
G) Microbe neutralization
H) Fine Filtration
I) Phosphate Removal
(Aerobic and Anaerobic)
J) Sulphur Removal (Aerobic
and Anaerobic)
K) Water Ejection
A) Water collection
When water is collected from
a source. This could be from the sewers of a city, or could be
disturbed water in a construction zone.
B) Bulk filtration
It is here that the large
debris is removed from the water. Debris usually consists of
trees, rocks and other undesirables.
C) Flocculation
Flocculants remove the fine
dirt and other materials that gives drinking water its clear, colourless
appearance. Flocculants attach themselves to many dirt particles,
which increases their mass.
D) Rapid mixing
This necessary step is
needed to facilitate equal distribution of the flocculent in the water.
E) Settling
After the rapid mixing step
is complete, the water forms large flocs, which drift to the bottom of
the settling pond.
F) Decanting
The clear water on top, is
removed from the settled flocs, which are now called sludge.
G) Microbe neutralization
Although the water has a
pleasant clear, colourless appearance, it may not be safe to other life
forms due
to the microorganisms or other contamination present. A biocide such as chlorine
or Ultra Violet lamps are used to neutralize the organisms.
H) Fine filtration
Fine filtration uses other
chemicals to remove organisms and fine particulates
from the water. The water is almost ready to be ejected into the
river at this stage.
I) Phosphate Removal
Some municipalities require
the removal of phosphates from water to meet current provincial
guidelines. This is usually performed in multiple steps in various
aerobic and anaerobic chambers.
J) Sulphur Removal
Some municipalities require
the removal of Sulphur from water to meet current provincial guidelines.
This is usually performed in multiple steps in various aerobic and
anaerobic chambers.
K) Water Ejection
Once water meets all
criteria and guidelines, it can be safely ejected into the river.
The following Screenshot
displays a computer program designed for a consulting company to
calculate the appropriate dose of a water treatment chemical.
Appropriate information has
been removed to protect current contracts and agreements with applicable
companies.
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