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Industrial Wastewater Treatment System
What
is an Industrial Wastewater Treatment System and How Does it Work?
SAMCO
For industrial
companies producing wastewater as part of its process, some type of wastewater
treatment system is usually necessary to ensure safety precautions and
discharge regulations are met.
The most
appropriate industrial wastewater treatment system will help the
facility avoid harming the environment, human health, and a facility’s
process or products (especially if the wastewater is being reused).
It will also help
the facility curb heavy fines and possible legal action if wastewater is being
improperly discharged into a POTW (publicly owned treatment works) or to the
environment (usually under a National Pollutant Discharge Elimination System,
or NPDES, permit).
But what is
a wastewater treatment system and how does it work?
The complex answer
to this question (which largely depends on the wastewater characterization in
relation to regulatory requirements for discharge from
the plant) is simplified and broken down for you below:
What is a wastewater treatment system?
A wastewater
treatment system is a system made up of several individual technologies
that address your specific wastewater treatment needs.
Treating wastewater
is rarely a static process, and a wastewater treatment system that is
engineered to accommodate fluctuations in treatment needs will go a long way in
avoiding costly replacements/upgrades down the line.
An efficient and
well-designed wastewater treatment system should be able to handle:
· process variations in contamination and flow
· variations in water chemistry needs and required chemical
volumes adjustments
· possible changes in water effluent requirements
What’s included in a basic wastewater treatment system?
As mentioned above,
the exact components of a wastewater treatment system depend on the wastewater
characterization in relation to regulatory
requirements for discharge from the plant, but in
general, a basic wastewater treatment system typically includes some type of:
· clarifier to settle suspended solids that are
present as a result of treatment
· chemical feed to help facilitate the
precipitation, flocculation, or coagulation of any metals and suspended solids
· filtration to remove all the leftover
trace amounts of suspended solids (again, the level of filtration needed will
depend on the degree of suspended solids removal required to pass local
discharge regulations)
· Final pH adjustment and any post
treatment
· control panel (depending on the level of
automated operation needed)
Depending on the needs
of your plant and process, these standard components are usually adequate,
however, if your plant requires a system that provides a bit more
customization, there might be some features or technologies you will
need to add on.
For example, for
facilities that generate biological demand such as food and beverage a
biological treatment system will be required to reduce the BOD (biochemical
oxygen demand), etc.
What does a wastewater treatment system typically remove?
A wastewater
treatment system might be made up of the technologies necessary to remove any
number of the following:
Biochemical oxygen demand
Biochemical oxygen
demand, or BOD, refers to the amount of dissolved oxygen needed by aerobic
biological organisms to break down organic matter into smaller molecules.
High levels of BOD
indicate an elevated concentration of biodegradable material present in
the wastewater and can be caused by the introduction of pollutants such as
fecal waste, cleaning, and wash-down from food processing or fertilizer runoff.
Nitrates and phosphates
If large amounts of
nitrates and/or phosphates are not removed from wastewater and these nutrients
are discharged into local environments, they can lead to an increase BOD and
extensive weed growth, algae, and phytoplankton.
This can further
lead to eutrophication, or the deoxygenation in a body of water, killing
the organisms and potentially leading to hypoxia or environmental dead zones.
Pathogens
Pathogens are
bacteria, viruses, fungi, or any other microorganisms that can be present in
wastewater that can lead to all kinds of health issues, including acute
sickness, severe digestive problems, or death.
When domestic or
industrial wastewater contains these harmful pathogens and is not treated, it
can spread illnesses and diseases such as cholera, dysentery, salmonellosis,
hepatitis A, botulism, and giardiasis, to name a few.
Metals
Mostly found in
wastewater as a result of various industries, manufacturing processes, when
left in wastewater in high concentrations, metals can cause extensive
damage to the environment and human health.
They are
particularly damaging because they don’t break down and tend to accumulate,
causing toxic environs.
Total suspended solids
Total suspended
solids (TSS) in wastewater, the organic and inorganic solid material suspended
in the water, can, like many of the other contaminants listed, harm aquatic
life.
They can also be
problematic if the wastewater is being reused for a process, so depending on
whether or not you need to discharge your wastewater in a publicly owned
treatment works (POTW) or environment, or reuse the wastewater for process,
will determine how harmful the TSS will be.
TSS can decrease
levels of oxygen in aquatic environments and kill of insects. They can
also scale and foul piping and machinery.
Total dissolved solids
Total dissolved
solids (TDS) are any anions, cations, metals, minerals, or salts found in
wastewater.
They can cause
issues with aquatic life, irrigation and crops, and they can also seep into
groundwater. TDS can be generated in wastewater from just about any industry.
Synthetic chemicals
When pesticides and
other chemicals are used / made in the manufacturing process, they can be
transmitted to humans and the environment through wastewater, causing
damage to the environment and human health.
Some common
chemicals found in wastewater include diethylstilbestrol, dioxin, PCBs, DDT,
and other pesticides.
These “endocrine
disruptors” can block hormones in the body and affect the functions these
hormones control.
How does a wastewater treatment system work?
Specific treatment
processes vary, but a typical wastewater treatment facility process will
usually include the following steps:
Coagulation
Coagulation is a
process where various chemicals are added to a reaction tank to remove the bulk
suspended solids and other various contaminants.
This process starts
off with an assortment of mixing reactors, typically one or two reactors that
add specific chemicals to take out all the finer particles in the water by
combining them into heavier particles that settle out.
The most widely
used coagulates are aluminum-based such as alum and polyaluminum chloride.
Sometimes a slight
pH adjustment will help coagulate the particles, as well.
Flocculation
When coagulation is
complete, the water enters a flocculation chamber where the coagulated
particles are slowly stirred together with long-chain polymers (charged
molecules that grab all the colloidal and coagulated particles and pull them
together), creating visible, settleable particles that
resemble snowflakes.
Sedimentation
The gravity settler
(or sedimentation part of the wastewater treatment process) is typically a
large circular device where flocculated material and water flow into the
chamber and circulate from the center out.
In a very slow
settling process, the water rises to the top and overflows at the perimeter of
the clarifier, allowing the solids to settle down to the bottom of the
clarifier into a sludge blanket.
The solids are then
raked to the center of the clarifier into a cylindrical tube where a slow
mixing takes place and the sludge is pumped out of the bottom into a
sludge-handling or dewatering operation.
The dewatering
process takes all the water out of the sludge with filter or belt presses,
yielding a solid cake.
The sludge water is
put onto the press and runs between two belts that squeeze the water out, and
the sludge is then put into a big hopper that goes to either a landfill or a
place that reuses the sludge.
The water from this
process is typically reused and added to the front end of the clarifier.
Filtration
The next step is
generally running the water overflow into gravity sand filters.
These filters are
big areas where they put two to four feet of sand, which is a finely crushed
silica sand with jagged edges.
The sand is
typically installed in the filter at a depth of two to four feet, where it
packs tightly.
The feed water is
then passed through, trapping the particles.
On smaller
industrial systems, you might go with a packed-bed pressure multimedia filter
versus gravity sand filtration.
Sometimes,
depending on the water source and whether or not it has a lot of iron, you can
also use a green sand filter instead of the sand filter, but for most part, the
polishing step for conventional wastewater treatment is sand filtration.
Ultrafiltration
(UF) can also be used after the clarifiers instead of the gravity sand filter,
or it can replace entire clarification process altogether.
Membranes have
become the newest technology for treatment, pumping water directly from the
wastewater source through the UF (post-chlorination) and eliminating
the entire clarifier/filtration train.
Disinfection
After the water
flows through the gravity sand filter, the next step is typically disinfection
or chlorination to kill the bacteria in the water.
Sometimes this step
is done upstream before filtration so the filters are disinfected and kept
clean.
If your system
utilizes this step prior to filtration, you will need to use more disinfectant
. . . this way the filters are disinfected and kept free from bacteria (as well
as the filtered water).
When you add the
chlorine up front you’re killing the bacteria and have less fouling. If
bacteria sits in the bed, you might grow slime and have to backwash the filters
more often.
So it all depends
upon how you’re system operates . . . whether your system is set up to
chlorinate upstream (prior to filtration) or downstream (after filtration).
Distribution
If the wastewater
is being reused in an industrial process, it’s typically pumped into a holding
tank where it can be used based on the demands of the facility.
If for municipal
use, the treated water is usually pumped into a distribution system of water
towers and various collection and distribution devices in a loop throughout the
city.
Other possible steps to the wastewater treatment process
Lime softening
In waters where you
have high hardness or sulfates, or other constituents you need to precipitate
or take out, a lime and/or a lime soda process is used. It raises the
pH, causing hardness and metals in the water to precipitate out.
Cold, warm, or hot
lime processes can be used, and each will yield a different efficiency. In
general, hotter water removes more hardness.
Ion exchange softening
In some industrial
and municipal applications, if there’s high hardness, there may be post
treatment for the removal of the hardness.
Instead of lime, a
softening resin can be used; a strong acid cation exchange process, whereby
resin is charged with a sodium ion, and as the hardness comes through, it has a
higher affinity for calcium, magnesium, and iron so it will grab that
molecule and release the sodium molecule into the water.
Special processes
As we stated above,
wastewater and effluent regulations differ everywhere you go. We have discussed
some of the most common steps in a wastewater treatment plant.
Typically, there
are special process steps to treat for a specific issues, such as the removal
of certain metals or organics, or to reduce TDS for recycling etc.
For these various
problems specific to your individual needs, careful consideration must be given
for the proper method of treatment.
In conclusion
SAMCO has over 40 years’
experience custom-designing and manufacturing wastewater treatment systems, so
please feel free to reach out to us with your questions.
For more
information or to get in touch, contact us here. You can also visit our
website to set up a call with an engineer or request
a quote.
We can walk you
through the steps for developing the proper solution and realistic cost for your
wastewater treatment system needs.
Since
its 1998 founding, SAMCO Technologies has provided custom water, wastewater,
process separation, and filtration solutions to a diverse range of industries.
Our individualized, project-based approach continues to define our niche in
modern industry, motivating us to deliver comprehensive, efficient solutions to
meet our customers’ unique needs.
At
SAMCO, we anticipate the needs of industry, and respond with forward-thinking
solutions. Our focus on industrial applications began in 1987 with the founding
of Northeast equipment supplier and systems servicer CS Kimeric. Acquired from
a Western New York soft water provider with over 30 years in the business, CS
Kimeric was established to provide specialized service for industrial
applications. Over the course of the next decade, it became clear that
industrial clients would benefit from working with a partner capable of
delivering comprehensive, concept-to-completion solutions. In 1998, founder and
CEO Richard Posa established SAMCO as an integrated provider of design,
fabrication, startup, and maintenance services.
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