Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02879781 2016-06-08
FLOATING TREATMENT BED FOR PLANTS
This invention relates to a method for extraction of contaminating
material from a body of water.
BACKGROUND OF THE INVENTION
It has been proposed to grow plants on floating areas where the plants
are supported on a flotation pad with their roots hanging into the water.
However
many difficulties and issues remain unsolved.
The following patents have been noted in this field:
Japanese patent 9-29283 is an early attempt to treat water using a
floating biomass.
US Patent 5337516 Hondulas is a land based system of high
complexity where the roots hang in the water.
US Patent 6322699 Fernandez provides an arrangement in which
waste water is treated using the general idea of using large plants grown on a
floating mass with their roots hanging to clear water. The patent is not
however filed
in Canada.
US Published application 2012/0228216 Gavrieli is a recent application
for a structure which floats and carries sheets on which microplants are
carried.
This uses agitation or aeration systems using power to drive them.
Published PCT application W096/36568 discloses a method of
extracting metals from water using hanging plants.
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Reference may be made to any of the above for further detail not
described herein.
Plants suitable for the method herein can be of the type Typha, genus
of about eleven species of monocotyledonous flowering plants in the family
Typhaceae. The genus has a largely Northern Hemisphere distribution, but is
essentially cosmopolitan, being found in a variety of wetland habitats. These
plants
are conspicuous and hence have many common names. They may be known as
bulrush, or reedmace, and as cattail, catninetail, punks, or corn dog grass.
These plants grown in wetlands at the edges of lakes are known to
carry out extraction of phosphates and other contaminants as these materials
are
taken up by the roots and thus absorbed into the plant. However this natural
process has been lost due to the reduction in areas of wetland. Also the
amount of
phosphates and similar contaminants has much increased leading to a serious
contamination of many lakes with the potential for environmental disasters.
In regard to one lake in Manitoba which is Lake Winnipeg, much of the
emergent vegetation in the Netley-Libau Marsh has been lost over the past
several
decades. Consequently, any removal of the nutrients in the Red River that
would
formerly have been intercepted by those plants has also been lost. The water
in
much of the Netley-Libau Marsh is too deep (> 1 meters) for plants to re-
establish
naturally.
Attempts have been made for new areas of growth to be established
on artificial islands.
However the construction of artificial islands for plant
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colonization in Netley-Libau Marsh would be costly and the investment would be
lost
if these islands are later found not to provide suitable habitat. If they do
work, the
practical use of vegetation growing on these islands would require the
invention of
amphibious equipment to harvest and transport the plants to land for
processing (for
biofuel and nutrient extraction benefits).
SUMMARY OF THE INVENTION
It is one object of the invention to provide a method for extraction of
contaminating material from a body of water.
According to one aspect of the invention there is provided method for
extraction of contaminating material from a body of water comprising:
forming a floating bed on which plants can be grown with their roots
=
hanging into the body of water;
locating the floating bed over an area where extraction of
contaminating material from the body of water is required;
growing the plants so as to form a root mass in the water and an
upstanding plant mass;
growing the plants to take up the contaminating material from the body
of water;
and harvesting the upstanding plant mass leaving at least part of the
root mass to continue growing into a new season.
Preferably the contaminating material is phosphate in lake water.
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Preferably the lake bed in the area of the floating bed is agitated to lift
the contaminating material to the roots.
Preferably the bed is agitated by aeration.
Preferably the bed is agitated by pumping water.
Preferably the bed is agitated by stirring the water by a propeller or the
like.
Preferably the floating bed has a skirt arranged around the periphery
hanging from the water to a position at or adjacent the lake bed.
Preferably the skirt is removable for moving the floating bed from the
location to a new location.
Preferably the floating bed is moved from the location to a harvesting
location and is returned to a location which may be the same or different
location for
further operation.
Preferably there is provided a support portion for a power source to
operate the agitation.
Preferably the power source is solar panels.
Preferably the power source drives a pump for air or water.
Preferably a plurality of floating beds is connected together.
Preferably the floating beds are connected together and provide
support between them for the power source.
Preferably each floating bed is towed to a harvesting location and
passed through a harvesting machine for cutting the plant mass and
transporting the
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plant mass from the bed to a processing location. However it is also possible
that a
floating harvesting machine is moved to the floating beds.
Preferably the harvesting machine includes a sickle knife and wherein
the floating bed passes underneath the knife.
5 Preferably the harvesting machine includes a rotating reel for
pulling
the crop mass into the machine.
Preferably the harvesting machine includes a conveyor belt for carrying
the plant mass along the machine to the processing location.
Preferably the harvesting machine is mounted on a fixed support in the
lake for passing the floating bed past the machine.
Preferably the floating bed has a width in the range 10 feet to 30 feet
so as to be maneuverable on the body of water.
Preferably the floating beds are connected together with a peripheral
flotation element.
Preferably the floating bed comprises a plurality of growth trays
connected together.
Preferably each growth tray comprises a layer of foam with cup shaped
openings for receiving individual plants.
Preferably each growth tray includes a mesh above and/or below the
foam layer.
Preferably each growth tray comprises a plurality of flotation members
such as tubes below the foam layer.
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Preferably each growth tray comprises a peripheral containing member
of for example a mesh material.
Preferably each growth tray comprises a plurality of plant carrying trays
shaped to fit into the openings in the foam with each plant carrying tray
being pre-
germinated and applied onto the foam at installation on the body of water.
Preferably each plant carrying tray is formed of a bio-degradable
material such as peat moss.
Preferably the growth trays are connected together to form the floating
bed by ties.
Preferably a part of the root mass also is harvested at the harvesting
machine and transported from the bed to a processing location. In this
situation a
part of the harvested root mass is used for cuttings in a new bed. The part of
the
harvested root mass is preferably harvested by a cutting blade underneath the
bed.
Preferably each plant carrying tray has the cups thereof covered by a
layer of a transparent film.
A new method has therefore been presented to create a bio-platform to
streamline the process of growing the cattails for subsequent harvesting.
The concept is to plant cattail plugs into floating trays to be positioned
in a larger floatation frame. The bio-platform is then deployed in the marsh
and when
fully grown towed back to the shoreline for harvesting. The frames are guided
under
stationary harvesting equipment and a conveyor belt moves cattail cuttings to
storage bins on land. Once the harvest is complete the frames are returned to
the
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marsh for continued plant growth. The system can be in place year-round except
during brief periods of harvesting.
The bio-platform comprise a floating structure containing sufficient bed
material to foster the initial growth of hybrid cattails (TyphaXglauca) until
the plants
become well-established and self-supporting.
The bio-platforms are sufficiently rugged that they survive ice
movement during the spring thaw; wave action; damage from exposure to
ultraviolet
light, animals, and vandalism; and accumulation of increasing plant mass over
time.
Individual bio-platforms can be linked together in various configurations at
the
deployment site, relative to prevailing water currents and winds, to provide
maximum
stability and longevity.
The bio-platforms can provide additional benefits: 1) they may help to
dissipate waves and promote long-term sediment accretion that enables natural
re-
vegetation to occur, 2) they may provide habitat for wildlife and fish in the
areas of
deployment, and 3) they may provide a vehicle for public education and
engagement
about wetland restoration, especially during harvesting periods.
Bioplatforms can be deployed in a wide variety of places where plant
growth is presently infeasible due to excess water depth, such as along rivers
and
lake inshore areas.
In one arrangement the harvesting machine defines a channel through
which each floating bed is passed with the sickle knife disposed across the
channel
for cutting the upstanding plant mass as the bed is passed through the
channel.
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Preferably the transparent film is slit at a location of the respective cup
to form an opening to allow plant growth through the transparent film while
the
transparent film remains arranged to encourage germination of the respective
plant
by greenhouse effect within the respective cup.
According to another aspect of the invention there is provided a
method for extraction of contaminating material from a body of water
comprising:
forming a floating bed on which terrestrial plants can be grown with
their roots hanging into the body of water;
locating the floating bed over an area where extraction of
contaminating material from the body of water is required;
growing the terrestrial plants so as to form a root mass in the water
and an upstanding plant mass;
growing the terrestrial plants to take up the contaminating material
from the body of water;
and harvesting the upstanding plant mass leaving at least part of the
root mass to continue growing into a new season;
wherein, in the step of harvesting, each floating bed with the terrestrial
plants thereon is passed through a harvesting machine at a harvesting location
for
cutting the plant mass and transporting the plant mass from the bed to a
processing
location;
wherein the harvesting machine includes a first sickle knife spaced
above a surface of the water so as to cut the upstanding plant mass as the
floating
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bed is passed underneath the first sickle knife.
Typically the floating bed is not submerged when it passes underneath
the first sickle knife.
Preferably a part of the harvested root mass is harvested by a second
sickle knife spaced below the first sickle knife so as to cut underneath the
bed.
Preferably the second sickle knife is spaced below the surface of the
water.
In one arrangement the harvesting machine defines a channel through
which each floating bed is passed with the first sickle knife disposed across
the
channel for cutting the upstanding plant mass as the bed is passed through the
channel.
According to a further aspect of the invention there is provided a
method for extraction of contaminating material from a body of water
comprising:
forming a floating bed on which terrestrial plants can be grown with
their roots hanging into the body of water;
locating the floating bed over an area where extraction of
contaminating material from the body of water is required;
growing the terrestrial plants so as to form a root mass in the water
and an upstanding plant mass;
growing the terrestrial plants to take up the contaminating material
from the body of water;
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and harvesting the upstanding plant mass leaving at least part of the
root mass to continue growing into a new season;
wherein there is provided a step of agitating a bed of the body of water
in the area of the floating bed to lift the contaminating material to the
roots;
5 wherein equipment used for agitation is positioned into the water
from
the floating bed which is arranged at a water surface such that the floating
bed
where the terrestrial plants are grown thereon is in spaced relation above the
bed of
the body of water which includes sediment containing contaminating material.
Preferably there is provided a power source carried on a support
10 portion of the floating bed that powers the equipment for agitation
locally at the
location of the floating bed.
In one arrangement the equipment used for agitation is depending
from locations along a periphery of the floating bed.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1A is a plan view of a floatation tray for a floating bed for using
the present invention.
Figure 1B is an isometric view of the floatation tray of Figure 1A.
Figure 10 is an isometric view of the floatation tray of Figure 1A.
Figure 2 is a top plan view of four floatation beds connected together
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for common operation on a body of water.
Figure 3 is a front elevational view of the floatation beds of Figure 2
Figure 4 is a side elevational view of a harvesting machine for
collecting the plant mass from a floatation bed.
Figure 5 is a top plan view of the harvesting system of Figure 4.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
The flotation bed of Figures 1A, 1B, 1C, 2 and 3 includes the following
components:
A heavy plastic square grid or mesh 1 for stabilizing peat tray 2 for cat-
tail plugs grown in a greenhouse.
Polyethylene foam pad 3 with an array of cup-shaped pockets to
contain peat plug tray.
Side frame 4 of preformed rigid inwardly facing C-channel.
Polyethylene pipe 5 with end capped for buoyancy.
Compressed air line 8.
Polyethylene pipe seal air tight for floatation frame 9.
Skirt 10 attached to contain aerated sediment and water.
Anchoring pocket 11 for weight chain to hold skirt down.
Solar panel 12 for power source for air pump.
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Air compressor pump 13.
Floating dock or support 14 to hold solar panel and air pump.
Pipes 5 act as a float grid system to stabilize the bottom of foam
containing the peat trays 2 holding the germinated plug. The stabilizer frame
4 is for
tray support from heavy wave action and moderate movement with clustered trays
within the floating perimeter frame 5.
The mesh 1 is the plastic grid for additional support of the foam pad for
holding the peat trays 2 level. More importantly the grid is where the roots
of cattail
will grow through and anchor to the float tray naturally.
Foam pad 3 is the foam tray floatation made from polyethylene foam
with cavities r cups 3A the shape of the peat trays 2 to accept the germinated
cattail
plugs in each cavity. This prevents the peat tray from sinking into the water.
The
cattail seedlings are initially grown in the peat tray 2 in a greenhouse. Once
matured
the plugs in the peat trays are introduced to the floating tray for growing
outdoors.
However as an alternative the tray containing the seeds and some soil
can be stored remotely and then supplied to the platform for assembly on site
whereupon the seeds germinate when they come into contact with the water.
An additional plastic grid (not shown) can be is positioned on top of the
peat trays 2 to prevent the trays from moving off the polyethylene foam
support from
wave action, wind and other movement actions from the floatation frame.
The preformed heavy plastic grid channel 1 is designed to encapsulate
the multi-layer substrates edges from parting during movement. Once the
cattail
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roots grow and cluster the bio-platform will float naturally.
The trays are assembled in the polyethylene pipe area 5 to contain
multi planted grow trays. This poly pipe also acts as a compressed air storage
tank
fed by the air compressor pump13. Around the perimeter of the polyethylene
pipe 8,
compressed air line is positioned into the water to activate the sediment bed
to move
phosphorus into the direction of the cattail root above. The skirt 10 is for
the
containment of the agitated sediment for vigorous root absorption. Anchoring
chain
ills used to keep the 10 skirt firm and taut during movement of bio platform
and
wave action. The whole floating dock is anchored in the body of water and
holds the
Bio Platforms in position during grow season which are then detached for
harvesting. It also acts as a platform for support equipment including solar
panels 12
and compressed air pump 13.
The apparatus shown is thus used in a method for extraction of
contaminating material from a body of water. The apparatus provides the
floating
bed on which plants are grown with their roots hanging into the lake water.
The
floating bed is located over an area A of the lake bottom where extraction of
contaminating material from the lake bottom is required. The plants are grown
on
the floating bed so as to form a root mass in the water and an upstanding
plant
mass. The plants are grown so that the plants take up the contaminating
material
from the lake bottom. The upstanding plant mass is harvested in the machine of
Figure 4 and 5 leaving the root mass to continue growing onto a new season.
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In order to increase the amount of contaminants extracted from the
bottom, the lake bottom and water in the area of the floating bed is agitated
to lift the
contaminating material to the roots. The bottom and the water at the bottom
can be
agitated by aeration, by pumping water or by stirring the water by a propeller
or the
like. The elements necessary to effect this agitation are driven by power from
the
solar cells. As the growing season is long, the agitation does not need to be
continuous so that if can occur only when sufficient power is available.
In order to contain the agitation action and to contain the agitated
water, the floating bed has the skirt 10 arranged around the periphery hanging
from
the water to a position at or adjacent the lake bed and held down by the
weight chain
11.
As shown in Figure 4, the skirt 10 is removed for moving the floating
bed from the location to a new location including the harvesting machine 20.
After
harvesting, the floating bed is moved from the harvesting location and is
returned to
an operating location which may be the same or different location for further
operation.
The individual floating beds are connected together simply by plastic
ties to form an island defined by a plurality of floating beds connected
together. The
connection includes panels 14 between the beds which act as support between
them for the power source, pump etc. The flotation tube 5 extends around the
full
periphery of the connected beds.
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During harvesting as shown in Figures 4 and 5, each floating bed is
separated from its island and towed to the harvesting location and passed
through a
harvesting machine 21 for cutting the plant mass and transporting the plant
mass
from the bed to a processing location 22. The processing location is typically
at a
5 remote
central location so that the crop is loaded onto trucks at a center 23 for
shipping to the location 22. Suitable loading systems are provided for
stacking the
crop using conventional agricultural equipment.
The harvesting machine 21 includes a sickle knife 24 arranged on fixed
platforms 25, 26 so that the floating bed passes underneath the knife between
the
10
platforms. The harvesting machine also includes a rotating reel 19 for pulling
the
crop mass into the machine and controlling its passage so that the bed is not
broken
up as the sickle knife cuts the material above the knife. The cut crop falls
onto a
conveyor 27 behind the knife 24 and from that conveyor is carried by an
extended
conveyor system 27A to the center 23.
15 As
shown in Figure 4 a part of the root mass is harvested by a knife
24A at the harvesting underneath the bed and is transported from the bed to
the
processing location 22 where a part of the harvested root mass is used for
cuttings
in a new bed as shown at 30 and a part can be used in the processing.
The harvesting machine is mounted on a fixed support defined by
platforms 25, 26 anchored to the lake bottom in the lake for passing the
floating bed
past the machine. Alternatively the machine can float on a floatation system
defining
a channel for the beds to pass through. In this case the machine can be moved
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from place to place to harvest beds at their location with the beds being
moved only
a short distance to the harvesting machine. Yet further the beds may remain
fixed
and the machine moved to them.
The floating bed has a width in the range 10 feet to 30 feet and
preferably 16 feet and a length of the order of 20 to 100 feet and preferably
48 feet
so as to be maneuverable on the body of water. Thus for example the bed may be
formed of separate sections which are 4 feet by 8 feet so that the sections
can be
easily managed and transported to the lake and the structure assembled at the
lake
to form the whole bed. As shown the 4X8 sections are connected into a bed of
four
sections wide and six sections long
The individual sections are connected together and the peripheral float
tube 5 added with the skirt 10.
As described above, each growth tray comprises a layer of foam 3 with
cup shaped openings 3A for receiving individual plants with layers of
reinforcing
mesh above the foam layer.
Each growth tray comprises a plurality of plant carrying trays 2 shaped
to fit into the openings 3A in the foam with each peat moss carrying tray
being pre-
germinated and applied onto the foam at installation on the body of water.
Each
plant carrying tray has the cups 2 thereof covered by a layer of a transparent
film 2A
which is slit after installation to allow plant growth. The transparent
material acts as
a greenhouse covering to encourage germination.
