Diffusion
Sedimentation
Diffusion allows dissolved forms of Phosphorus to be transferred from
the incoming surface water into the soil and back again on occasion. A
concentration gradient is what allows different forms of phosphorus to
move into and back out of the sediment. This concentration gradient
causes phosphorus to move from a region of high concentration to low
concentration resulting in the back and forward movement of phosphorus from the overlying water to the sediment or
vice versa.
The shallow, slow moving water found in wetlands allows for particulate matter (inorganic and/or organic
sediment) floating in the water column to settle out and
collect on the surface of the soil, in a process known as
sedimentation. This settling process allows for the removal of contaminants from the water.
Wetland Phosphorus Cycle
Plant uptake
Plants which are present in
wetlands typically root into
the soil or float around in the
overlying water. Inorganic
phosphorus, primarily orthophosphate, is then taken up
by these plants, ultimately
removing the phosphorus
form the water where it is
stored in the plants.
Microorganisms which live within
wetlands, utilize organic carbon for
energy by breaking down organic
matter, including plant detritus, organic sediments and peat. Organic
phosphorus compounds are broken
down into smaller organic molecules including particulate and
dissolved molecules. In the end,
these molecules are broken
down into inorganic phosphate
(orthophosphate) which can either be utilized as energy by the
microorganisms or released
back into the soil or water.
Sorption
Litterfall
Dead plant tissue such as
leaves and stems fall from
plants that live in and
around the wetland where they collect at the sediment/
water interface. The dead plant tissue sometimes contains inorganic phosphorus which was previously removed from the water through processes like plant uptake. The result is the accumulation of dead plant tissue
(detrius) containing phosphorus at the bottom of the wetland in the process known as litterfall.
Decomposition
Burial and peat accretion
Dead plant tissue (detrius) which has accumulated at the sediment/
water interface gradually is buried and incorporated into the soil. This
buried material represents the portion of organic material that is more
resistant to decomposition. Over time, the organic material ages while
it decomposes and compresses, forming peat in the process known as
peat accretion. This formation of peat allows for the long term storage
Sorption involves two processes. The first process is the
adsorption of inorganic phosphate by clays and iron or aluminum oxides present in the
soil. The second process involves the retention of inorganic phosphate (PO43-) with either iron
and aluminum oxides or dissolved calcium, to form solid compounds in the
sediment or water column. These processes allow for unstable inorganic phosphorus to become stable so they can
then be stored for long periods of time
in the process known as sorption.
The Future of Constructed Wetlands for
Wastewater Treatment
Treating aquaculture wastewater using constructed wetlands
at the Haliburton Fish Hatcheries will provide valuable information and insight for now and for the future. The efficiency
and effectiveness of biological, chemical, and physical wetland processes in treating wastewater will be established.
Alternative methods for treating wastewater will be begin to
develop based on the findings and information gathered
from this aquaculture treatment wetland. The surrounding
community will benefit from the educational opportunities
provided from this constructed wetland which they can carry
onto future generations.
With the help of the scientific community and the public, the
treatment of aquaculture wastewater through wetland processes can be made public in efforts of broadening the knowledge on wastewater treatment alternatives.
With any luck, one day constructed wetlands such as this,
may replace wastewater treatment plants of the present.
Haliburton Hatcheries Facts:
Since 1998, the Haliburton Fish Hatchery has
raised 200,000 Rainbow
and Brook Trout,
40,000 Walleye, and
70,000 Haliburton Gold
Lake Trout.
Constructed Wetland at the Haliburton Hatcheries
Treating Aquaculture
Wastewater using
Constructed
Wetlands
Haliburton Highlands Outdoor
Association
P.O. Box 184
Haliburton, Ontario
K0M 1S0
Phone: 705) 457-9664
Fax: (705) 457-9607
Email: [email protected]
Website: www.hhoa.on.ca
"Water should not be judged by its history,
but by its quality"
- L. Van Vuuren
How are Fish Hatcheries and Wetlands related?
As fish grow they excrete organic materials into the water.
This is generally considered aquaculture wastewater, similar
to human wastewater. If increased amounts of wastewater
enters into natural rivers and streams without treatment
then elevated algal levels and decreased oxygen levels can
occur. Ultimately, the same effect can occur when human
wastewater is not treated before entering into the environment. Wetlands aid in the treatment of aquaculture wastewater by using biological, physical, and chemical processes
to clean the water.
Wetlands Clean Aquaculture Wastewater
Typical plant species found in wetlands such as the common
reed (Phragmites australis), cattail (Typha spp.), and bulrush
(Scirpus spp.) allow microbes such as bacteria, fungi, algae,
and protozoa to attach and live on their exposed stems,
leaves, and roots. A symbiotic association between the
plant and the microbe occurs in which the plant is provided
with an increased ability to capture water and elements
esential to the plants growth such as phosphorus, zine,
manganese, and copper. In return, the plant provides the
microbe with carbohydrates and vitamins essential for the microbes
growth. Aquaculture
wastewater contains nutrients, metallic ions, and
other compounds in
which microbes modify
to obtain nutrients and
energy for carrying out
their life cycles. The
Common Wastewater Treatment Method
The treatment of wastewater generated by humans is
treated using wastewater treatment plants located in each
community. One, two, or even three treatment stages are
required before wastewater can be discharged back into
the surrounding area for consumption. The first stage,
known as primary treatment, allows the solids in the wastewater to settle to the bottom where it can be collected and
disposed of. (either in a landfill or an incinerator). Primary
treatment uses a
series of pools and
screens which settles the wastewater
enough to separate
solids from solution. At best, primary
treatment
might remove half
of the solids, organic materials and
bacteria from the
water. If this is the
only
treatment
stage for the water
then chlorine must
be used to kill remaining bacteria.
Secondary treatment of wastewater removes organic materials and nutrients using bacteria.
Large tanks contain bacteria which actively take in nutrients. The bacteria which have accumulated amounts of nutrients are then removed from the wastewater in settling
tanks. Once secondary treatment is completed, 90% of all
solids and organic materials are removed. The third and
final stage of wastewater treatment uses chemicals to remove phosphorus and nitrogen from the water. It should
be noted that in wetlands, soil bacteria take the place of
chemicals in removing phosphorus and nitrogen from the
water. Chlorine is further added to the water to kill all remaining bacteria before the discharge of the water.
Managing Water Quality in Canada
Health Canada sets the guidelines for Canadian drinking water based on various contaminants known to be
present. Although Health Canada sets the guidelines,
drinking water is a provincial, territorial and municipal
governments responsibility. It is their responsibility to
inform the public about pollution risks related to recreational uses of water in efforts of keeping public water safe. The collection and analyzation of water samples are compared to the Canadian drinking water
quality guidelines to ensure the water in each jurisdiction is safe to use. From the Canadian drinking water
quality guidelines, provincial, territorial and municipal
governments form water quality objectives and standards for their regions. The Health Canada water quality guidelines specify limits for substances and describe
conditions that affect drinking water quality. Regionally
established water
quality objectives
and standards specify the concentrations of substances
allowable in water
bodies. A water
quality safety test
must meet both the
regulations, objectives, and standards outlined by Health Canada and
setup by regional governments in order to pass the
test.
Wetland Nitrogen Cycle
Ammonification (Mineralization)
The transformation of organic nitrogen into ammonia is
known as ammonification or nitrogen mineralization.
Bacteria are typically responsible for the breakdown and
decomposition of nitrogen-based organic tissues consisting mostly of dead organic materials. These bacteria
and various fungi incorporates the nitrogen into amino
acids and proteins and releases the remaining nitrogen
into the soil water where it becomes ammonium ions
(NH4+). The amino acids and proteins which are produced, are taken up by plants to synthesis plant protein
enabling them to grown .
Nitrification
The oxidation of ammonium ions (NH4+) by bacteria into nitrate ions (N2-) is known as nitrification. Once the nitrate ions are formed they can
then be taken up by plants, allowing them to
grown.
Denitrification
Denitrification invovles the reduction of nitrate
(N03-) into volatile forms of nitrogen like nitrogen gas (N2) and nitrous oxide (N20) which are
then released into the atmosphere. The removal
of nitrogen in various forms into the atmosphere
in the process of denitrification occurs in sediments of wetlands with the help of denitrifying
bacteria.
Nitrogen Fixation
The replenishment of nitrogen in the soil occurs primarily as a result
of nitrogen fixation carried out by specialized bacteria. Nitrogen fixation is the process in which atmospheric nitrogen (N2) is reduced to
ammonium ions (NH4+). This reduction allows ammonium ions to
become available for transfer to carbon-containing compounds to produced amino acids and other organic nitrogen-containing compounds.
Nitrogen fixation is especially important because it is a key process in
which all living things depend.
Ammonia Volatilization
Ammonia present in the sediments of a wetland
can sometimes become gaseous at which time
they become unstable. Ammonia gas which is an
unstable form of nitrogen can be easily released
to the atmosphere in the process of ammonia
volatilization. The ability of ammonia to become
unstable tends to increase as the temperature of
the water and subsequent wetland becomes
warm.
Nitrogen Assimilation
The assimilation of inorganic nitrogen (N03– and
NH4+) into organic nitrogen compounds is known as
nitrogen assimilation. Initially, the conversion of nitrate (NO3-) to nitrite (N02-) occurs which is then followed by a reduction to ammonia (NH4+) by nitrite
reductase. The ammonia is incorporated into glutamine as an amino nitrogen which is then transferred
to 2-oxoglutarate to form two molecules of glutamate
by glutamate synthase. Nitrogen assimilation allows
for inorganic nitrogen present in the sediment to be
converted into organic nitrogen which can be used by
plants and organisms in the water of the wetland.
Nitrate—>Nitrite—>Ammonia—>Glutamine—>Glutamate
(NiR)
(GoGAT)
There are two enzymes which help to catalyze the
overall pathway which include:
•
nitrite reductase (NiR)
and glutamate synthase (GoGAT)
Primary Applications of Wetland Water Treatment
Industrial: Constructed Wetlands for De-Icing Fluid
Treatment, Edmonton Alberta
-Pollutants found in stormwater runoff at airports,
including surface and aircraft de-icing/anti-icing glycols can
be treated and removed to low levels in well-designed
constructed wetland systems. The Edmonton International
airport uses a 2.7ha constructed wetland to remove up to
230,000m3 of glycol-contaminated runoff anually.
Aquaculture: Rosewall Fish Farms Constructed
Wetland, Coral Creek BC
-111m3/day of salmon hatchery wastewater is treated
using constructed wetlands before it is discharged.
Haliburton Hatcheries Facts:
How are Fish Hatcheries and Wetlands related?
Since 1998, the Haliburton Fish
Hatchery has raised 200,000 Rainbow
and Brook Trout, 40,000 Walleye,
and 70,000 Haliburton Gold Lake
Trout.
Constructed Wetland at the Haliburton Hatcheries
Treating Aquaculture
Wastewater using
Constructed
Wetlands
Institutional: Combination Peat Filter and Constructed
Wetland, Forteau Newfoundland
-The connection of an existing septic system to a
combination natural peat filter and constructed wetland
wastewater treatment system has taken place allowing
each system to complement each other in the harsh
landscape which they operate in. The wetland operates
most efficiently in warmer weather, while the locally
available sphagnum peat moss excels at treatment in
colder weather.
Municipal : Constructed Wetlands, Cobalt ON
-The Town of Cobalt is undertaking a five year research
program with the Ministry of the Environment to
demonstrate the effectiveness of constructed wetland
technology even under extreme northern Ontario climatic
conditions.
Agricultural: Mushroom Farm Leachate Treatment
Wetland, Blenheim ON
- Irrigation leachate water used to irrigate mushrooms,
barn cleaning run-off and run-off from outdoor composing
toilets are treated using constructed wetlands with water
being directed back into the barns for re-use in irrigation
and barn cleaning. Water in excess of re-use is used in the
compost making process for mushroom growing media
Residential: Curve Lake PeatLand Sewage Treatment
Systems, Curve Lake First Nations
-A constructed wetland system was designed for a daily
flow rate of 14,850 L/day to treat wastewater from 27
bedrooms of a multi-residence building. The system
combines constructed wetland technology and peat
filtration.
Haliburton Highlands Outdoor
Association
P.O. Box 184
Haliburton, Ontario
K0M 1S0
Phone: 705) 457-9664
Fax: (705) 457-9607
Email: [email protected]
Website: www.hhoa.on.ca
"Water should not be judged by its history,
but by its quality"
- L. Van Vuuren
Fish hatcheries rely on the growth of fish and
therefore many chemicals are used to promote
growth and reduce disease in fish. As fish grow
they excrete organic materials into the water
they live in typically called aquaculture wastewater. However, aquaculture wastewater is not only
fecal matter from the fish, it can also include
chemical additives used in aquaculture including:
antibiotics to control diseases; pesticides to control parasites; hormones to induce spawning; anesthetics to immobilize fish during transport and
handling; and pigments, vitamins, and minerals
which promote rapid growth and desired qualities
in the fish. If increased amounts of aquaculture
wastewater enters into freshwater lakes and
streams without treatment then elevated algal
levels and decreased oxygen levels can occur.
With that said, wetlands can treat aquaculture
wastewater by means of biological, physical, and
chemical processes.
Wetlands Clean Aquaculture Wastewater
Typical plant species found in wetlands such as the common reed (Phragmites australis), cattail (Typha spp.), and
bulrush (Scirpus spp.) allow microbes such as bacteria,
fungi, algae, and protozoa to
attach and live on their exposed
stems, leaves, and roots. A symbiotic association between the
plant and the microbe occurs in
which the plant is provided with
an increased ability to capture
water and elements esential to
the plants growth such as phosphorus, zine, manganese,
and copper. In return, the plant provides the microbe
with carbohydrates and vitamins essential for the microbes growth. Aquaculture wastewater contains nutrients, metallic ions, and other compounds in which microbes modify to obtain nutrients and energy for carrying out their life cycles. The modification of compounds
produces alternative forms of the initial pollutant which
is then lost to the atmosphere (eg. denitrification), accumulated in wetland soil (eg. phosphorus), or taken up
and stored in plants. This modification of compounds by
microbes allows for the actual treatment and cleaning of
the wastewater. Aside from nutrient removal, wetlands
also remove bactiera and protozoans typical of aquaculture wastewater by attaching them to suspended solids
that are then trapped by wetland vegetation. Overtime,
the bacteria will die as a result of remaining outside their
host organisms, through degredation by sunlight, or from
low pH of wetland water.
Common Wastewater Treatment Method
The treatment of wastewater generated by humans is
treated using wastewater treatment plants located in
each community. One, two, or even three treatment
stages are required before wastewater can be discharged
back into the surrounding area for consumption. The
first stage, known as primary treatment, allows the solids
in the wastewater to settle to the bottom where it can
be collected and disposed of. (either in a landfill or an
incinerator). Primary treatment uses a series of pools
and screens which settles the wastewater enough to
separate solids from solution. At best, primary treatment might remove half of the solids, organic materials
and bacteria from the water. If this is the only treatment
stage for the water then chlorine must be used to kill
remaining bacteria. Secondary treatment of wastewater
removes organic materials and nutrients using bacteria.
Large tanks contain bacteria which actively take in nutrients. The bacteria which have accumulated amounts of
nutrients are then removed from the wastewater in settling tanks. Once secondary treatment is completed, 90%
of all solids and organic materials are removed. The third and
final stage of wastewater treatment uses chemicals to remove
phosphorus and nitrogen from
the water. It should be noted
that in wetlands, soil bacteria
take the place of chemicals in removing phosphorus and
nitrogen from the water. Chlorine is further added to
the water to kill all remaining bacteria before the discharge of the water.
The Future of Constructed Wetlands for
Wastewater Treatment
Treating aquaculture wastewater using constructed wetlands at the Haliburton Fish Hatcheries will provide valuable information and insight for now and for the future.
The efficiency and effectiveness of biological, chemical,
and physical wetland processes in treating wastewater
will be established. Alternative methods for treating
wastewater will be begin to develop based on the findings and information gathered from this aquaculture
treatment wetland. The surrounding community will
benefit from the educational opportunities provided
from this constructed wetland which they can carry
onto future generations.
Managing Water Quality in Canada
Health Canada sets the guidelines for Canadian drinking
water based on various contaminants known to be present. Although Health Canada sets the guidelines, drinking water is a provincial, territorial and municipal governments responsibility. It is their responsibility to inform the public about pollution risks related to recreational uses of water in efforts of keeping public water
safe. The collection and analyzation of water samples are
compared to the Canadian drinking water quality guidelines to ensure the water in each jurisdiction is safe to
use. From the Canadian drinking water quality guidelines,
provincial, territorial and municipal governments form
water quality objectives and standards for their regions.
The Health Canada water quality guidelines specify limits
for substances and describe conditions that affect drinking water quality. Regionally established water quality
objectives and standards specify the concentrations of
substances allowable in water bodies. A water quality
safety test must meet both the regulations, objectives,
and standards outlined by Health Canada and setup by
regional governments in order to pass the test.
With the help of the scientific community and the public,
the treatment of aquaculture wastewater through wetland processes can be made public in efforts of broadening the knowledge on wastewater treatment alternatives.
With any luck, one day constructed wetlands such as
this, may replace wastewater treatment plants of the
present.