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Wastewater Treatment
What is Wastewater Treatment?
Wastewater treatment is the process of converting
wastewater – water that is no longer needed or is no longer suitable for use –
into bilge water that can be discharged back into the environment.
It may be formed by a number of activities including
bathing, washing, using the toilet, and rainwater runoff.
Wastewater
is full of contaminants including bacteria, chemicals, and other toxins.
Its
treatment aims at reducing the contaminants to acceptable levels to make the
water safe for discharge back into the environment.
Having said that, what exactly is wastewater treatment and
how does it work? Well, that is what we are going to learn over the next couple
of sections.
Types of Wastewater Treatment
Plants
There are two wastewater treatment plants namely chemical
or physical treatment plants, and biological wastewater treatment plants.
Biological waste treatment plants use biological matter
and bacteria to break down waste matter.
Alternatively, Physical waste treatment plants use
chemical reactions as well as physical processes to treat wastewater.
While Biological treatment systems are ideal for treating
wastewater from households and business premises, Physical wastewater treatment
plants are mostly used to treat wastewater from industries, factories, and
manufacturing firms.
Note that Industrial Waste here is a matter of grave
concern as most of the wastewater from industries contain chemicals and other toxins that
can largely harm the environment.
According to Wikipedia,
“Wastewater treatment is a process used to remove contaminants
from wastewater or sewage and convert it into an effluent that can be returned
to the water cycle with minimum impact on the environment, or directly reused.
The latter is called water reclamation because treated wastewater can be used
for other purposes. The treatment process takes place in a wastewater treatment
plant (WWTP), often referred to as a Water Resource Recovery Facility (WRRF) or
a Sewage Treatment Plant (STP). Pollutants in municipal wastewater (households
and small industries) are removed or broken down.”
Step by Step Wastewater
Treatment Process
The following is a step by step process of how wastewater
is treated:
1. Wastewater Collection
This is the first step in the wastewater treatment
process.
Collection systems are put in place by the
municipal administration, homeowners as well as business owners to ensure that
all the wastewater is collected and directed to a central point.
Note that the wastewater collected here is primarily the
water used in our everyday activities like cooking utensils, taking a bath,
doing laundry, and more.
This water is collected and then directed to a treatment
plant using underground drainage systems or by exhauster tracks owned and
operated by business people.
The transportation of wastewater should however be done
under hygienic conditions.
The pipes or tracks should be leak-proof and the people
offering the exhausting services should wear protective clothing.
Since the slightest issue in the exhauster track might
affect the overall treatment process, businesses manning the process take
extra-care to prevent any mishap.
2. Odor Control
At the treatment plant, odor control is important, to say
the least.
Wastewater contains a lot of dirty substances that cause a
foul smell over time.
To ensure that the surrounding areas are free of the foul
smell, odor treatment processes are initiated at the treatment plant.
All odor sources are contained and treated using chemicals
to neutralize the foul smell producing elements. It is the first wastewater
treatment plant process and it’s very important.
3. Screening
This is the next step in the wastewater treatment process.
Screening involves the removal of large objects for
example nappies, cotton buds, plastics, diapers, rags, sanitary items, nappies,
face wipes, broken bottles or bottle tops that in one way or
another may damage the equipment.
Failure to observe this step results in constant machine
and equipment problems.
Specially designed equipment is used to get rid of grit
that is usually washed down into the sewer lines by rainwater.
The solid wastes removed from the wastewater are then
transported and disposed off in landfills.
4. Primary Treatment
This process involves the separation of macrobiotic solid
matter from the wastewater.
Primary treatment is done by pouring the wastewater into
big tanks for the solid matter to settle at the surface of the tanks.
The sludge, the solid waste that
settles at the surface of the tanks, is removed by large scrappers and is
pushed to the center of the cylindrical tanks and later pumped out of the tanks
for further treatment.
The remaining water is then pumped for
secondary treatment.
5. Secondary Treatment
Also known as the activated sludge process, the secondary
treatment stage involves adding seed sludge to the wastewater to ensure that it
is broken down further.
Air is first pumped into huge aeration tanks that mix the
wastewater with the seed sludge which is basically a small amount of sludge,
which fuels the growth of bacteria that uses oxygen and the growth of other
small microorganisms that consume the remaining organic matter.
This process leads to the production of large particles
that settle down at the bottom of the huge tanks. The wastewater passes through
the large tanks for a period of 3-6 hours.
6. Bio-solids handling
The solid matter that settles out after the primary and
secondary treatment stages are directed to digesters.
The digesters are heated at room temperature. The solid
wastes are then treated for a month where they undergo anaerobic digestion.
During this process, methane gases are produced and there
is a formation of nutrient-rich bio-solids that are recycled and de-watered
into local firms.
The methane gas formed is usually used as a source of energy at the treatment plants.
It can be used to produce electricity in engines or to simply drive
plant equipment. This gas can also be used in boilers to generate heat for
digesters.
7. Tertiary treatment
This stage is similar to the one used by drinking water
treatment plants which clean raw water for drinking purposes.
The tertiary treatment stage has the ability to remove up
to 99 percent of the impurities from the wastewater.
This produces effluent water that is close to drinking water
quality.
Unfortunately, this process tends to be a bit expensive as
it requires special equipment, well trained and highly skilled equipment
operators, chemicals, and steady energy supply.
8. Disinfection
After the primary treatment stage and the secondary
treatment process, there are still some diseases causing organisms
in the remaining treated wastewater.
To eliminate them, the wastewater must be disinfected for
at least 20-25 minutes in tanks that contain a mixture of chlorine and sodium
hypochlorite.
The disinfection process is an integral part of the
treatment process because it guards the health of the animals and the local
people who later use the water for other purposes.
The effluent (treated wastewater) is later released into
the environment through the local waterways.
This water may now be used in industries, for irrigation,
and to meet a range of other purposes like doing laundry and washing clothes.
9. Sludge Treatment
The sludge that is produced and collected during the
primary and secondary treatment processes requires concentration and thickening
to enable further processing.
It is put into thickening tanks that allow it to settle
down and later separates from the water. This process can take up to 24 hours.
The remaining water is collected and sent back to the huge
aeration tanks for further treatment.
The sludge is then treated and sent back into the
environment and can be used for agricultural use.
The Benefits of Wastewater
Treatment
Wastewater treatment has a number of benefits. For example, wastewater treatment
ensures that the environment is kept clean, there is no water pollution.
You probably know at this point, how important it is to
prevent water pollution.
After all, it causes countless ailments in both humans and
animals. In the worst cases, it might even lead to death.
Treating wastewater minimizes water pollution, thereby
keeping us safe and healthy.
We also laud this process because it ingeniously makes use
of the most important natural resource;
water.
After the treatment, the water can be used for cooling
machines in factories and industries.
It will minimize the need of using freshwater, thereby, in
a way, saving water.
Treating wastewater also prevents the outbreak of
waterborne diseases and most importantly, it ensures that there is adequate
water for other purposes like irrigation.
That is why it is extremely important to encourage this
process and make it a part of our daily lives.
Finally, one should note that wastewater is but a complex
combination of several special chemicals, nutrients, and most importantly,
metal particles.
Recovering the metal particles, in particular, can
effectively address the community level demands of useful natural resources.
Scientists are constantly employing new methods to enhance
the resource recovery process from wastewater, and thanks to them, we can now
use treated wastewater for a variety of purposes.
Conclusion
In summary, the wastewater treatment process is one of the
most important environmental conservation processes that should be encouraged
worldwide.
Most wastewater treatment plants treat wastewater from
homes and business places.
Industrial plants, refineries, and manufacturing plants
wastewater is usually treated at the onsite facilities.
These facilities are designed to ensure that the
wastewater is treated before it can be released to the local environment.
Some of the water is used for cooling the machines within
the plants and treated again. They try to ensure that nothing is lost.
It is illegal for disposing untreated wastewater into
rivers, lakes, oceans, or into the environment, and if found culpable one can
be prosecuted.
Either way, since wastewater is a matter of grave concern,
treating it should be encouraged time and again.
This will not just help save water thereby paving the way
towards a healthy and sustainable environment, but it will also prevent
water-borne hazards that put millions of human lives at stake.
Rinkesh. A true environmentalist by heart ❤️. Founded Conserve
Energy Future with the sole motto of providing helpful information related to
our rapidly depleting environment. Unless you strongly believe in Elon Musk‘s
idea of making Mars as another habitable planet, do remember that there really
is no 'Planet B' in this whole universe.
