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Anaerobic vs. Aerobic Wastewater Treatment Systems
What’s
the Difference?
SAMCO
Anaerobic and
aerobic systems are two types of biological wastewater treatment.
While they are
similar in many ways, they also differ substantially, inviting questions
like “Are both anaerobic and aerobic systems used in wastewater
treatment?” and “What is the difference?”
Indeed, anaerobic
and aerobic wastewater treatment technologies can be used independently or in
combination with one another.
In this post, we’ll
take a look at how anaerobic and aerobic wastewater treatment technologies
differ from one another, as well as their respective advantages and drawbacks
that lend to their ability to complement one another on a wastewater treatment
train.
What is the difference?
Anaerobic and
aerobic systems are both forms of biological treatment that use
microorganisms to break down and remove organic contaminants from wastewater.
While both rely on
a process of microbial decomposition to treat wastewater, the key
difference between anaerobic and aerobic treatment is that aerobic systems
require oxygen, while anaerobic systems do not.
This is a function
of the types of microbes used in each type of system.
While this defining
characteristic can seem small, it has a number of significant implications on
how each type of treatment system is designed and used for various treatment
scenarios.
Some of the
important ways in which anaerobic and aerobic treatment systems differ include
the following:
System design
Aerobic systems require
some means of supplying oxygen to the biomass, which may be accomplished by
wastewater treatment ponds (which work by creating a large surface area for
introducing air to the wastewater), and/or by incorporating some type of
mechanical aeration device to introduce oxygen into the biomass.
Due to the need to
circulate the wastewater or otherwise aerate it, aerobic systems tend to be
less energy efficient than their anaerobic counterparts.
By contrast, anaerobic
systems must be designed to prevent the exposure of the biomass sludge to air.
This can be
accomplished via airtight, enclosed digesters that are primarily used for batch
treatment cycles, or by upflow anaerobic sludge blanket (UASB) systems that
keep the biomass layer submerged below the treated effluent that, as the name
suggests, flows upward toward the surface of the tank.
As a result of
these system design differences, anaerobic systems tend to offer a few benefits
over aerobic systems, including lower operational costs and energy demands, though
they also tend to be slower, and usually require more upfront capital.
Suitability for waste stream characteristics
While anaerobic and
aerobic systems are capable of treating many of the same biological
constituents, there are some differences that make each technology better
suited for specific contaminants, concentration levels, temperatures, or other
wastewater stream characteristics.
In general, aerobic
treatment systems are best suited for streams with relatively low BOD/COD,
and are also used for removal of nitrogen and phosphorus.
On the other
hand, anaerobic systems are typically used for treatment of waste
streams with high concentrations of organic contaminants, and for warm
wastewater streams.
Waste products and byproducts
Anaerobic and aerobic
technologies differ in terms of the types of waste products that result from
treatment, which can make them more or less suited for a particular
application.
In this
arena, anaerobic treatment offers some benefits over aerobic treatment
systems, as they result in less overall sludge production, as well as
generation of valuable byproducts.
In many cases,
facilities are able to treat, then reuse and sell anaerobic byproducts, which
include methane-rich biogas that can be used as an energy source, as well as
sludge that is stable and safe for use as an agricultural fertilizer.
Despite these
benefits, anaerobic treatment systems often produce unpleasant odors, which
will need to be managed in some way.
Using anaerobic and aerobic treatment together
Anaerobic and
aerobic systems are most often paired for treatment of streams with a high
concentration of organic contaminants.
For these setups,
anaerobic treatment is used for initial reduction of organic contaminant
levels, while aerobic treatment is used as a secondary polishing step to
further reduce BOD and TSS.
In some cases, the
secondary aerobic treatment step is used to oxidize ammonia to form nitrate.
In general, using
both technologies together results in more efficient treatment than if an
aerobic system were used alone, as well as more complete contaminant removal
than if anaerobic treatment were used alone.
The appropriateness
of using one or both types of biological treatment ultimately depends on the
unique application and process conditions at a given facility.
How SAMCO can help?
SAMCO has over 40
years’ experience custom-designing and manufacturing biological wastewater
treatment systems for a range of industries and applications, so please feel
free to reach out to us with your questions.
Contact us
here to set up a consultation with an engineer or request
a quote.
We can walk you
through the steps for developing the proper solution and realistic cost for
your specific water treatment system needs.
To learn more about
the services and technologies that SAMCO offers, visit our page on
wastewater treatment solutions here.
If you’re
interested in learning more about anaerobic biological wastewater treatment
systems, these articles may be of interest to you:
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.
Today,
SAMCO serves the process water needs of clients across the nation and globe
from its headquarters in Buffalo, New York. Leveraging the collective skills of
experienced chemical, civil, environmental, electrical, mechanical and process
engineers, chemists, and skilled tradesmen, SAMCO blends a culture of teamwork,
commitment and passion to help solve your unique industrial water treatment needs.
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