All parts of all diffusers must be at the same submergence,
or air will not be evenly distributed. This is a requirement for any aeration
system. Some designs depend on a level floor to achieve level diffusers,
while others do not require that the floor be level.
Lagoons present special design problems, because it is
difficult or impossible to construct a lagoon with a level floor. Even
if the floor is level when the basin is new, sedimentation and other variables
assure that it will not be level after a period of operation. Three types
of retrievable lagoon diffusers are used by AerResearch – suspended,
floor mounted, and adjustable.
Important considerations in the design of a retrievable
and replaceable lagoon aeration system are (1) the cost of preparing the
basin floor for installation and (2) the operator's ability to level diffusers
or adjust their submergence in response to future changes.
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AerResearch floating lateral designs support either suspended aerators or floor-mounted
aerators and offer features not offered by our competitors. Suspension assemblies
remove all loads from the air hose. Multi-point suspensions guarantee that all
parts of each aerator will be at the same elevation. Adjustable suspensions
allow aerator submergence to be adjusted to accommodate changes due to replaced
diffuser membranes or other factors that change the operating pressure. Suspension
saddles distribute weight over a wide area of the lateral and can be moved when
loads cause laterals to sag. Flooded-tube aerator designs minimize the weight
of the aerator to make installation and maintenance easier. Internal ballast
protects synthetic liners and ensures that aerators can be easily lifted even
after being lowered into sticky mud. Linear designs mean that membrane replacement
is the easiest in the industry. Optional unions and valves on each feedline
allow easy isolation and removal or replacement of each aerator. And a wide
variety of enhanced quality options is available to increase the life of your
equipment.
AerResearch floor-mounted lagoon aerators are advantageous when the floor is
level and made of a hard material such as concrete, or when budgets are limited
so that the least expensive system is required even though maintenance costs
may be high. This requirement does not happen often with lagoons, but floor-mounted
aerators can be used in many other applications. Floor-mounted aerators are
often used when existing basins require supplemental oxygen. Typical examples
are the conversion of an existing chlorine contact basin to use as a post aeration
basin. Another common example is to provide supplemental oxygen to an existing
oxidation ditch. Floor-mounted lagoon aerators are convenient for use in small
activated sludge or digester basins when the ability to retrieve the aerators
is desired.
AerResearch adjustable lagoon aerators provide the best of both of the other
design concepts plus important benefits. Like suspended aerators, adjustable
aerators achieve equal submergence without depending on a level floor. Like
floor-mounted aerators, adjustable aerators allow all components to be installed
below water where they are protected from ultraviolet light, wind, ice and vandalism.
And unlike either of the other design concepts, operators do not have to lift
ballast when retrieving or replacing the aerators. Adjustable aerators represent
the ultimate in retrievable lagoon aerator design. When equipped with optional
features and quality-enhancing materials of construction, they represent the
ultimate for your client.
An equally important design consideration is the quality of components used
in the system, since these affect the life of the equipment. For example, it
is not uncommon for manufacturers to recommend such inexpensive options as plastic
rope when stainless steel cable is actually needed. AerResearch has a long-standing
commitment to recommending quality components. Examples include fiberglass-reinforced
polypropylene fittings when others recommend PVC, stainless steel cables and
saddles when others recommend plastic ropes attached with knots, reinforced
EPDM vacuum hose when others recommend polyethylene tubing, and separate cable
and saddle assemblies to hold the weight of suspended aerators when others recommend
that the weight of the ballasted aerator be applied to the air hose fittings.
A specially significant example of a poor recommendation is external ballast
for suspended aerators. External ballast accumulates sand and grit on top, and
this load increases the effective weight of the ballast. In addition, the ballast
"sucks into the mud" whenever it touches bottom, and this can sink the lateral
or pull hose fittings apart. Some even go so far as to recommend painted carbon
steel external ballast. AerResearch recommends internal stainless steel ballast
for this application. Further, we always recommend a suspension system which
allows the aerator submergence to be adjusted. We never recommend metal components
which are not stainless steel.
AerResearch offers three designs in its line of retrievable lagoon aerators.
Each has its own advantages and disadvantages, and each may be the best choice
for individual applications. When you receive a design recommendation from AerResearch,
you can be sure that all options have been evaluated for your particular needs,
and only the option with the greatest advantage is included in your recommendation.
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For a comparison of the three design concepts in PDF Format,
click the button on the left. (184 KB) |
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For a demonstration of the operation of the adjustable
aerator in PPT format, click the button on the left. (5.19 MB) |
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For a discussion of lagoon mixing in PPT format, click
the button on the left. (6.82 MB) |
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For a discussion of optional features and materials of
construction in PDF format, click the button on the left. (46 KB) |