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The Use of an Aeration System to Prevent Thermal Stratification of Water Bodies: Pond, Lake and Water Supply Reservoir


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Water bodies such as lakes, ponds or water supply reservoir show vertical stratification of their masses, at least for some extended time periods. Density differences facilitate the process of stratification. Temperature and dissolved substances contribute to density differences in water. As a result, thermal stratification can be established during the warm season if the water bodies are sufficiently deep. On the contrary, during the cold season surface cooling force the vertical circulation of water as a result turnover will occur. In warmer weather regions such as Bangladesh, India etc. this annual cycle spending more time in late summer and early fall. Thermal stratification is a common phenomenon here. Failure to identify and control, stratification, can cause low oxygen level, fish die-offs, excessive growth of plankton, failure of meeting regulatory standards, customers' expectations. So, identify the early onset of stratification and developed operational response procedures that introduce appropriate control measures such as aeration to avoid potential impacts and minimize any adverse effects.
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Applied Ecology and Environmental Sciences, 2014, Vol. 2, No. 1, 1-7
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© Science and Education Publishing
The Use of an Aeration System to Prevent Thermal
Stratification of Water Bodies: Pond, Lake and Water
Supply Reservoir
Khairul Hasan, Kaosar Alam, Md. Saidul Azam Chowdhury*
Department of Civil and Environmental Engineering, Shahjalal University of Science and Technology, Sylhet, Bangladesh
*Corresponding author:
Received November 15, 2013; Revised November 29, 2013; Accepted January 02, 2014
Abstract Water bodies such as lakes, ponds or water supply reservoir show vertical stratification of their masses,
at least for some extended time periods. Density differences facilitate the process of stratification. Temperature and
dissolved substances contribute to density differences in water. As a result, thermal stratification can be established
during the warm season if the water bodies are sufficiently deep. On the contrary, during the cold season surface
cooling force the vertical circulation of water as a result turnover will occur. In warmer weather regions such as
Bangladesh, India etc. this annual cycle spending more time in late summer and early fall. Thermal stratification is a
common phenomenon here. Failure to identify and control, stratification, can cause low oxygen level, fish die-offs,
excessive growth of plankton, failure of meeting regulatory standards, customers’ expectations. So, identify the early
onset of stratification and developed operational response procedures that introduce appropriate control measures
such as aeration to avoid potential impacts and minimize any adverse effects.
Keywords: thermal stratification, aeration system, destartification system, epilimnium, hypolimnium, thermocline
Cite This Article: Khairul Hasan, Kaosar Alam, and Md. Saidul Azam Chowdhury, The Use of an Aeration
System to Prevent Thermal Stratification of Water Bodies: Pond, Lake and Water Supply Reservoir.” Applied
Ecology and Environmental Sciences 2, no. 1 (2014): 1-7. doi: 10.12691/aees-2-1-1.
1. Introduction
Humanity needs to be prepared for the changes it
imposes upon the Earth, especially in times of global
change and of direct human impact on the hydrological
cycle. The anthropogenic impact of the last decades on our
aquatic environment has shown that a responsible use of
our natural resources is mandatory to guarantee
sustainable conditions [2]. Stratification is a natural
occurrence, in any static body of water. It occurs when the
surface layer of water, warmed by the sun, becomes less
dense than the water underneath it. The development of
layers within the profile of a water body is a common
phenomenon of stratification [9]. Without intervention, the
severity of stratification commonly increases, along with
the possibility of drawing poor quality water from a
storage reservoir as well as lower level of dissolved
oxygen, excessive growth of algae.
To avoid these problems, the widely used tool is
aeration. The purpose of aeration in lake management is to
increase the dissolved oxygen content of the water and
Aeration can also increase fish and other aquatic animal
habitat, prevent fish kills and improve the quality of
domestic and industrial water supplies and decrease
treatment cost [13]. In some cases, nuisance algae blooms
can be reduced. Again, aeration of lakes and reservoirs has
been used for a number of years as a method of improving
water quality. Aeration can be used for improvement of
drinking water supplies, providing enhanced fisheries
habitat and treatment of symptoms of eutrophication.
2. Water Bodies
In last few years the demand of water supply for
agriculture, livestock and fish production has increased
tremendously whereas ponds, lakes and water supply
reservoirs are the reliable source of water to fulfill the
Aeration can be arbitrarily divided into two basic
categories. Destartification systems, as the name implies,
uses compressed air to cause vertical water movement and
mixing of the lake water column. Hypolimentic systems
add oxygen to the lake without destroying the thermal
stratification [6].
The term lake collectively refers to reservoirs (man-
made impoundments), natural lake systems and smaller
ponds (man-made or naturally created) Water from the
surrounding watershed enters a pond or lake as stream
flow, surface runoff and groundwater.
2.1. Lake
A lake could be a body of comparatively still water of
considerable size, localized in an exceedingly basin, that's
enclosed by land with the exception of a watercourse,
2 Applied Ecology and Environmental Sciences
stream, or alternative variety of moving water that serves
to feed or drain the lake. Water temperatures in lakes
throughout summer months aren’t uniform from high to
bottom. 3 distinct layers develop: the highest layer stays
heat at around 65-75 degrees F (18.8-24.5 degrees C). The
center layer drops dramatically, typically to 4565 degrees
F (7.4-18.8 degrees C). Very cheap layer is that the
coldest, staying at around 39-45 degrees F (4.0-7.4
degrees C). Since light-weight doesn't penetrate to very
cheap, chemical process is proscribed to the highest layer.
Attributable to the hotter waters and additional plentiful
food provide the majority creatures pay the summer
months within the higher layer. During spring and fall the
lake temperature is additional uniform. Fish and
alternative animals’ are found throughout the layers of the
2.1.1. Biological Zones
Lakes contain several distinct zones of biological
activity, largely determined by the availability of light and
oxygen. The most important biological zones are the
euphotic, littoral and benthic zones [3].
Euphotic zone
The Upper layer of water through which sunlight can
penetrate is called euphotic zone. All plant growth occurs
in this zone. In deep water, algae are the most important
plants, while rooted plants grow in shallow water near the
shore. The depth of euphotic zone is determined by the
amount of turbidity blocking sunlight penetration. In most
lakes, the turbidity is due to algal growth, although color
and suspended clays may substantially reduce sunlight
penetration in some lakes. In the euphotic zone, plants
produce more oxygen by photosynthesis than they remove
by respiration. Below the euphotic zone lies the profundal
zone. The transition between the two zones is called the
light compensation level. The light compensation level
corresponds roughly to a depth at which the light intensity
is about one percent of unattenuated sunlight. It is
important to note that the bottom of the euphotic zone
only rarely coincides with the thermocline.
Littoral zone
The shallow water near the shore in which rooted water
plants can grow is called littoral zone. The extent of the
littoral zone depends on the slope of the lake bottom and
the depth of the euphotic zone. The littoral zone cannot
extend deeper than the euphotic zone.
Benthic zone
The bottom sediments comprise the benthic zone. As
organisms living in the overlying water die, they settle to
the bottom where they are decomposed by organisms
living in the benthic zone. Bacteria are always present.
The presence of higher life forms such as worms, insects
and crustaceans depends on the availability of oxygen.
Figure 1. Biological zones in a lake
2.1.2. Classification of Lake Based on Stratification
The thermal characteristics of lakes are a result of
climatic conditions that provide a useful physical
classification which is based upon the stratification and
mixing characteristics of the water bodies. Reference [5]
classified lakes as follows:
Dimictic lakes
Occur in the cool temperate latitudes. Overturn occurs
twice a year, normally in the spring and autumn. Heating
in the spring results in stratification with a warm water
epilimnion during the summer. The autumn overturn
results in homothermal conditions (at approximately 4°C)
which then cool to create a cold water inverse
stratification during the winter months. Spring warming
results in mixing and a re-establishment of the annual
cycle. The stratification and mixing processes for a large
dimictic lake are illustrated in Figure. This type of lake is
the most common form of lake. Since the cool temperate
latitudes encompass most of the world’s industrial nations
they have been subjected to the most intensive study and
represent the greatest part of our limnological knowledge.
Cold monomictic lakes
Occur in cold areas and at high altitudes (sub-polar).
The water temperature never exceeds 4°C and they have a
vertical temperature profile close to, or slightly below,
4°C. They have winter stratification with a cold water
epilimnion, often with ice cover for most of the year, and
mixing occurs only once after ice melt.
Warm monomictic lakes
Occur in temperate latitudes in subtropical mountains
and in areas strongly influenced by oceanic climates. In
the same way as their cold water counterparts, they mix
only once during the year with temperatures that never
falls below 4°C.
Figure 2. Lake thermal structure and classification based on mixing
characteristics [5]
Applied Ecology and Environmental Sciences 3
Figure 3. The global distribution of thermal lake types in relation to
latitude and altitude [12]
Polymictic lakes
Occur in regions of low seasonal temperature variations,
subject to rapidly alternating winds and often with large
daily (diurnal) temperature variations. These lakes have
frequent periods of circulation and mixing and may be
subdivided into cold polymictic, which circulate at
temperatures close to 4°C, and warm polymictic which
circulate at higher temperatures. As defined above, all
shallow lakes fall within this category.
Oligomictic lakes
Occur in tropical regions and are characterized by rare,
or irregular, mixing with water temperatures well above
Amictic lakes
Occur in the Polar Regions and at high altitudes. They
are always frozen and never circulate or mix. Waters
beneath the ice are generally at, or below, 4°C depending
on the amount of heat generated from the lake bed or by
solar radiation through the ice. These lakes show inverse
cold water stratification.
2.2. Pond
In general, a pond could be a body of standing water,
either natural or semisynthetic, that's typically smaller
than a lake. Wet ponds accommodate a permanent pool of
standing water that promotes a stronger atmosphere for
gravitate sinking, biological uptake and microbe activity.
Runoff from every new storm enters the lake and partly
displaces pool water from previous storms. Water
temperature is fairly even from high to bottom and
changes with air temperature. There’s very little wave
action and also the bottom is typically coated with mud.
Plants can, and sometimes do, grow on the pool edge. The
number of dissolved element could vary greatly
throughout every day. In extremely cold places, the
complete pool will freeze solid.
The water quality of the surface waters of the state, as
well as all lakes and ponds, is regulated through statutes
(RSA 485-A) and rules (Env-Ws 1700). These laws and
laws create no distinction between lakes and ponds. Each
ought to meet all an equivalent water quality standards.
In earth science (the study of midland waters), surface
waters are divided into lotic (waters that flow in a very
continuous and definite direction) and lentic (waters that
don't flow in a very continuous and definite direction)
environments. Waters within the lentic category gradually
fill in over geologic time and the evolution is from lake to
pond to wetland. This evolution is slow and gradual, and
there is no precise definition of the transition from one to
the next.
2.3. Reservoir
A reservoir is a natural or artificial lake, storage pond
or impoundment from a dam which is used to store water.
Reservoirs may be created in river valleys by the
construction of a dam or may be built by excavation in the
ground or by conventional construction techniques such as
brickwork or cast concrete.
3. Thermal Stratification
The thermal stratification of lakes, ponds or reservoirs
refers to a change in the temperature at different depths,
and is due to the change in water's density with
temperature. Anyone who has taken a summer swim and
gone through the warm surface water to feel the icy water
a few feet underneath, has felt the most obvious effect of
thermal stratification.
Figure 4. Typical temperature profile from a stratified lake in the
temperate zone, showing the division of the water into three layers of
different density
The surface layer remains on top and the lower layer,
deprived of surface contact and insulated from the sun,
continues to get colder. This increases the difference in
density between the two layers and makes it even more
difficult for them to mix together. Once strongly
established, this stratification persists until falling
temperatures in autumn breaks down the density
difference between the two layers allowing them to mix
together again.
The significance of thermal stratification to anglers is
that the lower layer of water, deprived of surface contact,
slowly loses its dissolved oxygen and become less able to
support aquatic life. In deep lakes and reservoirs, this has
the effect of confining Cold water species, like trout, to a
narrow zone below the high temperature surface water but
above the bottom layer of cold water lacking oxygen. A
good echo sounder will sometimes show this prominent
layer of fish, with nowhere to go and very little to eat, and
the angler who can accurately get a lure or bait into this
"fish zone" can be extremely successful.
4 Applied Ecology and Environmental Sciences
3.1. Basic Characteristics of Stratification
Thermal Stratification is a term meaning temperature
layering. Some of the important features of stratification
A layer of aerobic water, near the surface, known as
the epilimnium, that is relatively warm and high in
dissolved oxygen (commonly above 7 ppm). In this
zone, temperature and dissolved oxygen (D.O.)
levels tend to be maintained by the penetration of
sunlight and mixing created by wind [9].
A layer of water, known as the hypolimnium, that is
commonly anaerobic, extends from the bottom of the
reservoir and is relatively cool and low in dissolved
oxygen (commonly below 3 ppm) [3].
A very thin layer of water, known as the thermocline,
where a rapid change in temperature and dissolved
oxygen occurs in between the epilimnium and
Stratification becomes more severe during warmer
months when the intensity and duration of sunlight
increases, and mixing from reservoir inflow
decreases due to reductions in stream flow [9]. As the
severity of stratification increases, the contrast in
water temperature and D.O. between the epilimnium
and hypolimnium tends to become more pronounced,
and the position of the thermocline tends to rise,
effectively increasing the proportion of the
Figure 5. Stratification during summer
3.2. Seasonal Cycle of Thermal Stratification
During the summer, the surface water of a lake is
heated both indirectly by contact with warm air and
directly by sunlight. Warm water, being less dense than
cool water, remains near the surface until mixed
downward by turbulence from wind, waves, boats or other
forces. Because this turbulence extends only a limited
distance, the result is an upper layer of well-mixed, warm
water floating on the lower water, which is poorly mixed
and cool. Because of good mixing the epilimion will be
aerobic. The hypolimnion will have a lower DO and may
become anaerobic. The boundary is called the thermocline
because of the sharp temperature change that occurs
within a relatively short distance. The depth of the
epilimnion is related to the size of the lake. It is as little as
one meter in small lakes and as much as 20 meters or
more in large lakes. The depth of the epilimnion is also
related to storm activity in the spring when stratified is
developing. A major at the right time will mix warmed
water to a substantial depth and thus create a deeper than
normal epilimnion. Once formed, stratification is very
stable. It can be broken only by exceedingly violent
storms. In fact, as the summer progresses, the stability
increase because the epilimnion continues to warm, while
the hypolimnion remains at a fairly constant temperature.
In the fall, as temperatures drop, the epilimnion cools
until it is denser than the hypolimnion. The surface water
then sinks, causing overturning. The water of the
hypolimnion rises to the surface where it cools and again
sinks. The lake thus completely mixed. If the lake is in a
cold climate, this process stops when the temperature
reaches 4°C, since this is the temperature at which water is
most dense. Further cooling or freezing of the surface
water results in winter stratification. As the water warms
in the spring, it again overturns and becomes completely
Figure 6. Seasonal cycle and turnover of thermal stratification
3.3. Factors That Affects Turnover
Wind, Solar radiation input, Depth, Air temperature,
Lake or pond size, Lake or pond bottom topography,
Streams entering lake or pond etc. are the main factors
that affects turnover.
As Thermal stratification occurs in a seasonal cycle
with the thermocline becoming more severe in late
summer and late winter. Lakes and ponds in warmer
weather regions experience a shorter annual cycle
spending more time in late summer and early fall
3.4. Problems related to stratification [4]
Fish kills: The spatial distribution of fish within a
lake is often adversely affected by thermal
stratification and in some cases may indirectly cause
large die-offs of recreationally important fish.
Foul odors: As result of the release of hydrogen
Low oxygen level: For most ponds or lakes, oxygen
production is limited to wind diffusion, wave action
and photosynthesis, which often leads to dangerously
low dissolved oxygen levels, thermal stratification
and stagnation.
Weed growth: Excessive amounts of aquatic weeds
throughout the water column can affect the balance
of the lake or pond’s ecosystem and also interferes
with recreational activities such as swimming,
fishing, boating and irrigation. Unchecked, nuisance
Applied Ecology and Environmental Sciences 5
aquatic vegetation can also cause water quality issues,
fish die offs, foul odors and an unsightly appearance.
Algae growth: Algae feeds on nutrients in the water
that are released from decaying matter such as fallen
leaves, grass clippings, fish waste, uneaten fish food,
dead bugs, dead aquatic vegetation, as well as
phosphorous and nitrogen that washes into the pond
from the surrounding land. Large growth of algae can
lowering the depth of the lake as well as the further
use if it.
3.5. Potential Effects of Stratification on
Urban Water Authorities
One of the common causes of problems to water
resource operations is that the thermocline rises above the
designated off take level and water of poor quality is
drawn from the reservoir. Some of the most common
problems that can be associated with reservoir
stratification [9] are outlined below:
Water treatment processes can become difficult to
manage and the cost of treatment can increase
The ability to meet regulatory standards in regard to
drinking water quality can become compromised.
Water odor can become a problem, particularly as a
result of the release of hydrogen sulphide.
Manganese and iron particles can become prevalent
in anaerobic water. If these particles are not detected
during treatment, clothing items can become stained
during washing as these particles react with the
oxygen particles I washing detergent.
The likelihood of receiving customer complaints can
Adverse effects on the ecosystem within the reservoir
can occur as a result of the formation of minerals due
to low D.O. levels, potential impacts on aquatic life
such as fish kills and the potential for algal blooms to
occur may also increase.
In extreme cases, a severely stratified reservoir may
potentially need to be isolated from a water supply system
due to poor water quality.
4. Introducing Stratification Control
A healthy pond is all about nutrient and oxygen balance
[7]. The level of oxygen and how it is distributed
throughout the water column is one of the keys to pond
health. Oxygen in a pond comes from two natural sources
- diffusion from the air and, most importantly, as a
byproduct of photosynthesis. An imbalance of oxygen
occurs during the night, overcast days, ice/snow cover
when no sunlight is present and photosynthesis cannot
occur. Temperature also has a major impact on a pond's
balance of oxygen. As the temperature increases, thermal
stratification - the difference in temperature at different
depths of water - starts to occur.
An aeration system allows you to supplement the
actions of nature by adding a supply of diffused oxygen.
The use of aeration as a control measure can be very
effective to reduce stratification. Aeration would normally
be accomplished for the following purpose [7]:
Aeration to limit the growth of algae and minimize
algae concentrations in the pond.
Increase the Dissolved Oxygen (D.O.) level in the
basins in order to allow fish propagation.
Increase D.O. levels in the basin to eliminate odors
and gasses escaping from the benthal (sludge)
For ponds or lakes which are very deep, there can be a
need for destartification.
4.1. Destartification Systems
Destratification is a type of artificial circulation that
completely mixes a stratified lake's waters from top to
bottom and thereby eliminates or prevents summer
stratification [6] (the division of a lake into water layers of
different temperatures).
It is possible to provide the required oxygen in situ by
artificially mixing the lake or water bodies. It has been
shown [11] that the primary mechanism of oxygen transfer
is at the water surface even if compressed air is used as
mixing device. Riddick [10] concluded that “an aerator
should be regarded as a cheap, uncomplicated and
relatively efficient device for pumping water”.
Two techniques [13] are most common: air injection
and mechanical mixing.
Air Injection (Diffuser) systems are the most
common destartification method. A compressor on
shore delivers air through lines connected to a
perforated pipe(s) or other simple diffuser(s) placed
near the bottom, typically in the deep area of the lake.
The rising air bubbles cause water in the
hypolimnion to also rise, pulling this water into the
epilimnion. When the colder, hypolimnion water
reaches the lake surface; it flows across the surface
and eventually sinks, mixing with the warmer
epilimentic water. Evebtually, the entire lake
becomes of nearly equal temperature with oxygen
distributed throughout. This aeration technique is
sometimes referred to as the air-lift method of
Mechanical axial flow pumps use a “top-down”
approach to set up a circulation pattern. A floatation
platform and frame support an electric motor,
gearbox, drive shaft and large propeller (6-15 feet
diameter). Its rotation pushes water from the lake
surface downward, setting up a circulation pattern
that prevents thermal stratification.
Figure 7. Air injection system
6 Applied Ecology and Environmental Sciences
Figure 8. Mechanical axial flow pumps
Other systems
Reference [13] proposed other systems as follows:
Surface spray units consist of a float supporting an
electric motor-driven impeller. The rapidly-turning
impeller pulls water up a vertical tube and throws it
out in an umbrella or fountain shaped spray a few to
many feet above the lake surface. Atmospheric re-
aeration occurs in the sprayed water and at the
agitated lake surface.
Figure 9. surface Spray
Figure 10. Impeller-Aspirator systems
Impeller-Aspirator systems consist of an electric
motor-driven impeller at the bottom of a hollow shaft
extending at an angle down into the water. The
assembly floats on the lake surface. The rapidly
turning impeller draws air down the shaft and propels
water and air bubbles into the lake. Aeration takes
place through air bubble and at the agitated lake
Pump and Cascade system consists of a large pump
that moves lake water to the top of a ramp like chute
containing numerous baffles. The water cascades
down the ramp and falls back into the lake at a point
located as far as possible from the water inlet.
Aeration occurs in the cascade chute and in the
plunge pool as the water flows away from the ramp.
4.2. Hypolimnetic System
This system was developed in an attempt to solve some
of the problems inherent in destratification systems,
particularly to maintain the cold water layer at the bottom
of a lake or reservoir [6]. The technique introduces oxygen
to the water at the bottom of the lake without disrupting
the thermocline.
There are a few disadvantages when compared with
destratification systems. The supply of oxygen to the
hypolimnion is relatively slow because of the small
surface area available in the aeration apparatus across
which the oxygen transfer is made. For water bodies with
large hypolimnia or large surface areas, several units must
be considered.
Hypolimentic aerators can be further distinguished into
two basic groups [6]: full lift and partial lift.
Full lift systems transfer water from the hypolimnium
to the surface consequently back to the hypolimnium. This
system tends to be less prone to causing nitrogen super
saturation in the hyplimnion than the partial lift system.
Figure 11. Hypolimentic aeration unit (full lift, [11])
Figure 12. Hypolimentic aeration unit (partial lift, [1])
4.3. Benefits of Aeration [7]
Dissolved oxygen increases to healthy levels
Stagnation is replaced by a convection current
Applied Ecology and Environmental Sciences 7
Thermal and Oxygen Stratification are eliminated
Biological processes start to reduce the muck layer
Nutrient balance is achieved
Reductions in algae and weed growth
Odors are eliminated as an exchange of gasses occurs
No longer a breeding ground for Mosquito's and
Midge Fly's
Fish habitat is restored
5. Conclusion
Aeration systems have been used to improve water
quality of lakes and reservoirs. However in some cases no
net benefit and even worsening of conditions have
occurred because of inappropriate use of aeration systems.
Because of this, a detailed evaluation of prevailing
chemical and biological limnology and anticipated effects,
as well as an engineering evaluation of most appropriate
technology is absolutely necessary.
On the other hand, too much oxygen in the water can
cause a variety of problems resulting from the water
becoming supersaturated [9]. Supersaturated water can
cause corrosion (the gradual decomposition of metal
surfaces) and sedimentation problems. In addition, air
binding occurs when excess oxygen comes out of solution
in the filter, resulting in air bubbles which harm both the
filtration and backwash process.
Aeration can also cause other problems unrelated to the
supersaturated water. Aeration can be a very energy-
intensive treatment method which can result in overuse of
energy [9]. In addition, aeration of water can promote
algal growth in the water and can clog filters.
[1] Bernhardt, H., “Impondment destartification by mechanical
pumping water quality behavior in reservoir”, Public helath
Survice publication No. 190, Cincinnati, Ohio. 616 p, 1969.
[2] Boehrer, B., and Schultze, M., “Stratification of lakes”, Reviews of
Geophysics, 46(2), RG2005.2008.
[3] Davis, M. L., and Cornwell, D. A., “Introduction to environmental
engineering”, (Vol. 3). Landsberg: McGraw-Hill.1998.
[4] Global Climate Change News Brief, “Climate Change Impact on
Freshwater Wetlands, Lakes & Rivers”.2010.
[5] Hakanson, L. and Jansson, M., “Principles of Lake
Sedimentology”, Springer-Verlag, Heidelberg, 316 pp.1983.
[6] Nordin, R.N. and McKean, C.J.P., “A Review of lake Aeration as
a technique for Water Quality Improvement”, province of British
Columbia, Ministry of Environment, Assessment and Planning
Division, APD Bulletin 22.1982.
[7] “Oxygen & Circulation a Key to Pond & Lake
Health”, 33769 Groesbek Hwy Fraser, MI 48026, 888-986-9995.
[8] Peavy, H. S., Rowe, D. R., and Tchobanoglous, G.,
“Environmental engineering”, (Vol. 1, No. 9). New York:
[9] Perks, C., “Dealing with stratification within a water supply
reservoir”, In 69th Annual Water Industry Engineers and
Operators’ Conference (pp. 30-36).2006.
[10] Riddick, T. M., “Forced circulation of reservoir waters”, Water
and Sewage Works, 104(6), 231.1957.
[11] Smith, S. A., Knauer, D. R., and Wirth, T. L., “Aeration as a lake
management technique”, Wisconsin Dept. of Natural Resources
Technical bulletin No. 87, Wisconsin Department of Natural
Resources, 39 pgs. 1975.
[12] Wetzel, R. G., “Limnology”. 743 pp. WB Saunders Co.,
[13] Hudson, H. and B. Kirschner. Lake Notes: Lake Aeration and
Circulation”, Illinois Environmental Protection Agency and the
Northeastern Illinois Planning Commission. 1997.
... Aeration has been proposed as a less expensive tool compared to dredging for reducing organic sediments and hypoxia [12]. It mixes the water column, increases dissolved oxygen (DO) concentrations and accelerates aerobic decomposition of organic matter [13][14][15]. For example, the cost of aerating our study canal was $10,000-15,000 USD for initial setup plus~3,500 USD annually for electricity (Allied Group USA, personal communication). ...
... In contrast, the cost of environmental dredging is $50-75 USD per cubic meter (i.e., $200,000 for~4,000 m 3 of muck from the same canal). Artificial aeration has been used in lakes and aquaculture ponds to enhance water quality, while little in situ data is available to inform predictions of ecosystem outcomes for estuaries undergoing aeration [12,[14][15][16][17][18][19]. Those freshwater studies focus on chemical reactions and microbial processes [14,[16][17][18][19]. ...
... Artificial aeration has been used in lakes and aquaculture ponds to enhance water quality, while little in situ data is available to inform predictions of ecosystem outcomes for estuaries undergoing aeration [12,[14][15][16][17][18][19]. Those freshwater studies focus on chemical reactions and microbial processes [14,[16][17][18][19]. The few studies of estuarine aeration are limited to laboratory or mesocosm investigations [20][21][22][23][24], with the exception of a few in situ studies examining water quality only [13,25,26]. ...
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Fine-grained organic-rich sediments (FGORS) are accumulating in estuaries worldwide, with multi-faceted negative ecosystem impacts. A pilot experiment was carried out in a residential canal of the Indian River Lagoon estuary (IRL, Florida, USA) using an aeration treatment intended to mitigate the harmful ecological effects of organic-rich sediment pollution. Planktonic and benthic communities were monitored, and environmental data collected throughout the aeration process. Results were compared against control conditions to evaluate the efficacy of aeration in the mitigation of FGORS. During the aeration process, hurricane Irma impacted the study area, bringing heavy rainfall and spawning a brown tide event (Aureoumbra lagunensis). The overall thickness and volume of FGORS, and the organic content of surface sediments did not change during the aeration treatment. Dissolved oxygen was higher and ammonium concentrations were lower in aeration canal bottom water compared to the control canal. During treatment, aeration did facilitate benthic animal life when temperatures dropped below 25°C, likely due to water column mixing and the increased capacity of water to hold dissolved gasses. In general, aeration did not significantly change the planktonic community composition relative to the control canal, but, during the post-bloom period, aeration helped to weaken the brown tide and phytoplankton densities were 35-50% lower for A. lagunensis in aeration canal surface water compared to the control canal. Aeration has important management applications and may be useful for mitigating algal blooms in flow-restricted areas and promoting benthic communities in cooler environments.
... Various mixing and oxygenation systems have been deployed in drinking water reservoirs to mitigate water quality problems. Standard mixing and oxygenation systems, including side-stream oxygenation systems [6], bubble plumes [7,8], and other technologies [9,10], have successfully improved water quality in lakes and reservoirs. ...
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Water quality deterioration is a major problem faced by reservoirs globally, owing to the inflow of pollution from industrial and municipal activities. Water-lifting aeration is an in situ water quality improvement technology that mixes and oxygenates deep water bodies in reservoirs to improve pollution control efficiency and water quality. While previous studies have mainly focused on the mixing process in the reservoir outside the water-lifting aerator (WLA), knowledge of the internal flow remains limited. In this study, a two-phase flow within a WLA system was numerically studied using the volume of fluid (VOF) method to comprehensively analyze the internal two-phase flow characteristics and the influence on the water-lifting and oxygenation performance of the system. The statistical analysis results showed that increasing the aeration chamber volume enhanced the bottom oxygenation performance by 27% because of the prolonged time of the deflector plate outlet outflow. Additionally, increasing the air release rate enhanced the water-lifting performance by 47%, which was induced by the shortened air piston release period. This study demonstrates the internal flow mechanism of the WLA and provides technical support for parameter optimization design, which has significant scientific research and engineering application value.
... The external load is reduced by controlling the inflow of effluents from sewage or industrial wastewater treatment facilities (James and Pollman, 2011;Hwang et al., 2021) and creating wetlands (Gregoire et al., 2009;Ham et al., 2010;Shutes, 2001) for point and nonpoint source management, respectively. Reducing internal load measures include artificial destratification (Antenucci et al., 2005), hypolimnetic oxygenation and aeration system (Bryant et al., 2011;Hasan et al., 2014;Ma et al., 2015), and sediment dredging (Björk et al., 2010;James and Pollman, 2011;Liu et al., 2016). As suggested by Liu et al. (2014) and Nürnberg (2007), the combination of reservoir flow control measures with external load reduction or hypolimnetic withdrawal can be a low-cost and sustainable reservoir restoration measure while increasing the efficiency of pollutant removal. ...
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In Korea, estuary reservoirs are one of the main water resources for agriculture, generally used for water supply, while ensuring an appropriate water level. The recent inflow of pollutants from watersheds is aggravating water pollution problems in these reservoirs; to address this issue, the government has implemented effective measures, including the control of water level and basin-management measures. Effective water-level management of estuary reservoirs can reduce the environmental impact on freshwater and coastal fishing. However, the current water-management measures mainly focus on securing water and ensuring the feasibility of sea dike construction. Therefore, in this study, we evaluated the effect of drainage gate operation on the water quality of the Ganwol reservoir. We established a watershed-estuary linkage model, the Hydrological Simulation Program-Fortran, Environmental Fluid Dynamics Code, and Water Quality Analysis Simulation Program (HSPF-EFDC-WASP) linkage simulation system, to comprehensively consider the watershed and water-body characteristics and study the water quality changes for differently managed water-level scenarios. The effect of water level on the water quality of the estuary reservoir was evaluated by considering differently managed water-level scenarios in the linkage model. The results indicated that the difference in the water quality for each water-level scenario was larger at the lower point (GW1) of the estuary reservoir than at the upper point (GW3). At GW3, the water quality tended to improve with the increasing water level. GW1 was significantly affected by the operation of the drainage gate; at GW1, the lower the management level was, the higher the water-quality improvement effect, owing to the improvement in the flow in the estuary caused by the increase in the discharge frequency. The study results can be used as basic data to prepare an optimal water resource management plan for estuary reservoirs by estimating the water-level impact on their future hydrology and water quality.
... The DO and the nutrients' total phosphorus (0.66), and nitrate (0.65), have a moderate association. Previous studies supported this finding (Lindenschmidt et al. 2009, Rong et al. 2016, Bierlein et al. 2016, Julie & Lindenschmidt 2017, as given in (Table 6) there is also a weak correlation between dissolved oxygen and chlorophyll 0.28 (Chen et al. 2019) and a high correlation between dissolved oxygen and sediment oxygen demand 0.77 while the CBOD and dissolved oxygen are negatively highly correlated -0.70 (Oskar et al. 2020), which is often observed the inverse strong relation between CBOD and dissolved oxygen (Chowdhury et al. 2014, Chai & Draxler 2014. Our model was validated based on the concept of using Pearson's correlation coefficient and the The model clearly simulated successfully the changes and differences occurring in the water density curve which led to seasonal stratification that is occurring during the summer season. ...
The work presented here is a model approach based on WASP8 (Water analysis simulation program) a water quality model simulated to represent contaminants at the surface and bottom sediments of Kurtboğazı dam reservoir in Ankara city. However, our water quality output variables: are temperature, nitrate, total phosphorus, total Kjeldahl nitrogen, dissolved oxygen, Chlorophyll a, and ammonia. To ensure the model represents the actual case at the reservoir, the results from the simulation model were calibrated using actual data from the Kurtboğazı dam site, the calibration utilizes statistical techniques. The first method was the goodness-of-fit, R2 between model variables and field data, and the results were in the range of 0.86 to 1.0 indicating excellent linear association. The second technique was the RE, the values of which obtained were less than 1, elaborating acceptable results. The dam reservoir Kurtboğazı had been affected by the negative impact arising from dissolved oxygen depletion in the hypolimnetic layer during stratification periods and that had been well documented. However, the processes of oxygen consumption at the sediment-water interface are still difficult to grasp conceptually and mainly linked to sediment oxygen depletion and the phenomena of sediment oxygen demand SOD. The novelty of this research work is the development of a quality model to predict the reactions of state variables that are occurring at the water body and how they interact with each other and their influence on the overall quality status of the Kurtboğazı reservoir, and the crucial factors influencing the depletion of oxygen at the water column; secondly, the effect of anoxic condition on the benthic flux and the impact of anoxia condition on the ratio of nitrogen to phosphorus ratio at the reservoir. It was evident from the results of calibration that the model successfully simulated the correlation of the parameters influencing the anoxic condition, and benthic flux and ratio shift from nitrogen-limited during the summer to phosphorus-limited at the beginning of winter.
... Generally, the greater the depth of the lake is, the more stable the stratification will be [4][5][6]. Hasan et al. explored lakes and reservoirs in tropical regions and found that the thermal stratification stability of water bodies in the late summer and early autumn seasons was still relatively large, and the mixing process was relatively slow [7]. Bonnet et al. observed the Villerest Reservoir in France for two years and concluded that it was in thermal stratification from April to September [8]. ...
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Thermal stratification is a common phenomenon in lakes and reservoirs. It has a significant influence on water quality dynamics. The destruction of the thermal stratification of lakes and reservoirs can affect the water environment, improve the water quality and the water environment quality and prevent the occurrence of eutrophication. In this study, computational fluid dynamics (CFD) combined with a Eulerian two-phase flow model is used to predict the damage caused by an airlift device to the thermal stratification phenomenon of lake water. The results show that the two devices with different sizes can contribute to a certain exchange of kinetic and thermal energy, affecting the liquid velocity and temperature in the lake water under the condition of different gas velocities. Furthermore, the degree of damage to the thermal stratification phenomenon of lake reservoir is small. However, with the same gas velocity, the device with a guide plate can have a greater impact on the liquid velocity and temperature in the lake water. Further prediction results show that the airlift installed with a guide plate can affect the heat transfer of liquid in the lake and reservoir better and destroy the thermal stratification phenomenon effectively. The quantitative results of model prediction can provide an effective basis for future field scale-up experiments.
... The circulation induces downward water movement that shifts heat and oxygen towards the bottom layers of the water column (Gibbs and Howard-Williams, 2018). Water column mixing allows for simultaneous destratification and oxygenation by causing hypolimnion water to mix uniformly with the water column leading to a near-isothermal state and dissolved oxygen (DO) increase in eutrophic lakes (Fast et al., 1973;Hasan et al., 2013). Oxygenated conditions during mixing can suppress internal nutrient loading to promote nutrient-limited conditions. ...
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This review summarizes current knowledge on mechanical (artificial mixing, hypolimnetic aeration, dredging, and sonication) and biological (biomanipulation, macrophytes, and straws) methods for the management of cyanobacterial blooms in drinking water sources. Emphasis has been given to (i) the mechanism of cyanobacterial control, (ii) successful and unsuccessful case studies, and (iii) factors influencing successful implementation. Most mechanical and biological control strategies offer long-term control. However, their application can be cost-prohibitive and treatment efficacy is influenced by source water geometry and continual nutrient inputs from external sources. When artificial mixing and hypolimnetic oxygenation units are optimized based on source water characteristics, observed water quality benefits included increased dissolved oxygen contents, reduced internal loading of nutrients, and lower concentrations of reduced ions . Treatment efficacy during oxygenation and aeration was derailed by excessive sedimentation of organic matter and sediment characteristics such as low Fe/P ratios. Dredging is beneficial for contaminated sediment removal, but it is too costly to be a practical bloom control strategy for most systems. Sonication control methods have contradictory findings requiring further research to evaluate the efficacy and applicability for field-scale control of cyanobacteria. Biological control methods such as biomanipulation offer long-term treatment benefits; however, investigations on the mechanisms of field-scale cyanobacterial control are still limited, particularly with the use of macrophytes and straws. Each control method has site-specific strengths, limitations, and ecological impacts. Reduction of external nutrient inputs should still be a significant focus of restoration efforts as treatment benefits from mechanical and biological control were commonly offset by continued nutrient inputs.
... Aerobic conditions also promote the conversion of toxic ammonia to other forms of nitrogen. Aeration improves water transparency, can minimize organic matter accumulation and helps to eliminate odors and gases escaping from the sludge deposits in lakes (Chowdhury et al., 2014). According to Balangoda et al., (2015), artificial circulation results in huge reduction of chlorophyll a concentration (Microcystis sp., Aphanizomenon sp. and Anabaena sp. as dominant genera) along the water column and across sampling stations which can be due to a shift in dominant phytoplankton species, favoring dinoflagellates or green algae over cyanobacteria. ...
Conference Paper
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Lakes provide various provisional, regulating and cultural services. Pollution of water bodies due to human activities affects the physico-chemical characteristics of water, leading to changes in aquatic community structure and deterioration of the lake environment. Water quality and microalgal diversity of six lakes (Yediyur, Sankey, ISRO layout, Uttarahalli, Doraikere and Doddakalsandra) in Vrishabhavathi valley of Greater Bangalore, Karnataka were assessed in this study. Uttarahalli lake is more polluted than other lakes with higher ionic, organic and nutrient contents. Excessive growth of phytoplankton had reduced the ionic, nutrients and organic contents in all lakes. Biomonitoring of these lakes revealed the presence and dominance of cyanobacteria (Microcystis sp.). Many pollution tolerant algae were present in all 6 lakes that are indicators of organic pollution, thus, making water unfit for drinking and recreational purposes. The flow of ionic and nutrient rich sewage water into lakes led to profuse growth of cyanobacteria, oxygen depletion (hypoxia), high turbid conditions, loss of biodiversity and reduction in recreational value. In the monitored lakes, composition of Cyanobacteria: Doraikere (98%), Doddakalsandra (98%), Uttarahalli (94%), ISRO layout (80%), Yediyur (75%) and Sankey (44%). Among, Cyanobacteria, Microcystis sp. dominated all the lakes. Sankey lake had less cyanobacterial growth and supported highest algal diversity than the other lakes due to the improved oxygen levels with the installation of fountains. Appropriate measures like adoption of integrated wetland system (Jakkur model) and aeration (as in Sankey lake) can help in improving the water quality as well as biodiversity of these lakes.
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Hypolimnetic aeration is an effective management strategy for mitigating oxygen deficiency in dam reservoirs caused by thermal stratification (ThS). However, designing an optimal hypolimnetic aeration system based on dissolved oxygen (DO) concentration evaluation has yet to be considered in the literature. This study proposed an innovative optimization model utilizing the non-dominated sorting genetic algorithm-II (NSGA-II) for up to 4 aerators, considering two main objectives: (i) minimizing DO concentration deviation from the standard limit and (ii) minimizing aerator(s) operation energy. This optimization model was developed based on five primary decision variables: the location of the aerator(s) (length and depth), the aeration rate, and the operating time (start and end date). The NSGA-II optimization approach was coupled with the CE-QUAL-W2 simulation model for each identified period of ThS to simulate DO concentrations. To satisfy the conflicting objectives of the primary beneficiaries involving the Ministry of Energy and the Regional Water Organization, a two-step decision-making framework was introduced, utilizing the Nash bargaining (NB) and weighting method (WM) techniques. In order to show the practicality and effectiveness of the suggested framework in enhancing the DO concentration within a dam reservoir, the novel simulation optimization framework was implemented in a real-world case study of the Karkheh dam reservoir (KDR) in Iran. The findings revealed that applying an optimal hypolimnetic aeration system significantly improved the DO concentration, reaching at least twice the level without an aerator. However, the influence of aerators was not long-lasting, gradually diminishing when their operations ceased. Considering the importance of increasing DO concentration to mitigate the adverse effects of ThS, the four aerators system was chosen as the optimal compromise design for the KDR.
In closed water bodies with significant organic pollution, anoxification due to thermal stratification leads to the elution of nitrogen and phosphorus from the bottom sediment and the generation of sulfide, resulting in further degradation of the water environment. This study focuses on the water quality dynamics in an organically polluted reservoir exhibiting long-term anoxification using two approaches: (1) field observations of seasonal changes in vertical profiles of dissolved oxygen, nitrogen, phosphorus, and sulfide and (2) construction of a water quality prediction model based on an ecosystem model incorporated with anaerobic biochemical processes. Iron and sulfate reduction occurred simultaneously because nitrate–nitrogen was reduced by denitrifying bacteria after the anoxification, and iron reduction became the main factor of the increase in ammonium–nitrogen and phosphate–phosphorus. The redox state of the bottom sediment surface, when anoxification began to occur, greatly affected the water quality dynamics caused by gradual reductive reactions under anaerobic conditions. Furthermore, the calculation accuracy of ammonium–nitrogen, phosphate–phosphorus, and sulfide was highly improved by modifying the conventional model based on the field observations. The characteristics of water quality under anaerobic conditions were sufficiently reflected in the upgraded ecosystem model. The proposed water quality prediction model could be used to quantitatively estimate the water environment dynamics in organically polluted water bodies. The model could be developed further in the future to solve the problems caused by long-term anoxification.
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Many lakes show vertical stratification of their water masses, at least for some extended time periods. Density differences in water bodies facilitate an evolution of chemical differences with many consequences for living organisms in lakes. Temperature and dissolved substances contribute to density differences in water. The atmosphere imposes a temperature signal on the lake surface. As a result, thermal stratification can be established during the warm season if a lake is sufficiently deep. On the contrary, during the cold period, surface cooling forces vertical circulation of water masses and removal of gradients of water properties. However, gradients of dissolved substances may be sustained for periods much longer than one annual cycle. Such lakes do not experience full overturns. Gradients may be a consequence of external inflows or groundwater seepage. In addition, photosynthesis at the lake surface and subsequent decomposition of organic material in the deeper layers of a lake can sustain a gradient of dissolved substances. Three more geochemical cycles, namely, calcite precipitation, iron cycle, and manganese cycle, are known for sustaining meromixis. A limited number of lakes do not experience a complete overturn because of pressure dependence of temperature of maximum density. Such lakes must be sufficiently deep and lie in the appropriate climate zone. Although these lakes are permanently stratified, deep waters are well ventilated, and chemical differences are small. Turbulent mixing and convective deep water renewal must be very effective. As a consequence, these lakes usually are not termed meromictic. Permanent stratification may also be created by episodic partial recharging of the deep water layer. This mechanism resembles the cycling of the ocean: horizontal gradients result from gradients at the surface, such as differential cooling or enhanced evaporation in adjacent shallow side bays. Dense water parcels can be formed which intrude the deep water layer. In the final section, stratification relevant physical properties, such as sound speed, hydrostatic pressure, electrical conductivity, and density, are discussed. The assumptions behind salinity, electrical conductance, potential density, and potential temperature are introduced. Finally, empirical and theoretical approaches for quantitative evaluation from easy to measure properties conclude this contribution.
This monograph introduces a unique approach to the overall concept of environmental engineering, an approach that emphasizes the relationship between the principles observed in natural purification processes and those employed in engineered processes. First, the physical, chemical, mathematical, and biological principles of defining, quantifying, and measuring environmental quality are described. Next, the processes by which nature assimilates waste material are discussed and the natural purification processes that form the bases of engineered systems are detailed. Finally, the engineering principles and practices involved in the design and operation of conventional environmental engineering works are covered at length.
A Review of lake Aeration as a technique for Water Quality Improvement", province of British Columbia, Ministry of Environment, Assessment and Planning Division
  • R N Nordin
  • C J P Mckean
Nordin, R.N. and McKean, C.J.P., "A Review of lake Aeration as a technique for Water Quality Improvement", province of British Columbia, Ministry of Environment, Assessment and Planning Division, APD Bulletin 22.1982.
Impondment destartification by mechanical pumping water quality behavior in reservoir
  • H Bernhardt
Bernhardt, H., "Impondment destartification by mechanical pumping water quality behavior in reservoir", Public helath Survice publication No. 190, Cincinnati, Ohio. 616 p, 1969.
Dealing with stratification within a water supply reservoir
  • C Perks
Perks, C., "Dealing with stratification within a water supply reservoir", In 69th Annual Water Industry Engineers and Operators' Conference (pp. 30-36).2006.
Lake Notes: Lake Aeration and Circulation
  • H Hudson
  • B Kirschner
Hudson, H. and B. Kirschner. " Lake Notes: Lake Aeration and Circulation ", Illinois Environmental Protection Agency and the Northeastern Illinois Planning Commission. 1997.