At present, there is no difference
in the water condition of the rivers, canals or ditches because
these water sources have repeatedly become a receptacle for garbage
and waste. This situation, combined with the community's rapidly
growing population, causes an endless water pollution problem.
In the past some people had a subtle way of preserving the quality
of public water sources. For instance, they identified many ponds
as holy water sources so that people could not bathe or wash their
clothes in the ponds, and were only allowed to take the water
home for consumption. Unfortunately, those old-fashioned tricks
no longer work with people today because we place more importance
on computers than on nature.
Formulation of a plan to manage
wastewater sources is a big problem because today people lack
a sense of unified participation in working together to solve
the problem. As a result, the management of wastewater in complicated
areas has not achieved much success. Therefore, a possible solution
must start from setting order within a small society and assigning
responsibility to the local people to implement the solution.
Aquatic plants together with the aerator, are then used for treating
wastewater; a solution which has potential for improving water
quality for a small society.
The various plants have diverse
characteristics. Some, such as cactuses can withstand dry conditions,
while some grow better in salty conditions, such as mangrove (Rhizophora)
and Aegiceras. Some types prefer living in damp conditions, while
others grow well in water. Although these plants have different
living preferences, they do have certain common needs to keep
growing-sunlight, moisture, air, and nutrients.
Many kinds of aquatic plants,
especially the commonly known types of submersed plants, can be
used to treat wastewater. But to achieve the greatest benefit,
it is important to select the types which are suitable to the
water conditions; that is, the amount of wastewater and the characteristic
of the water sources, whether they are ponds, reservoirs, rivers,
canals, water delivery canals, drainage canals or natural canals.
In certain water sources, water is motionless; some places water
drifts slowly; and other places flows strongly. These factors
are the variables to be considered in designing a plan for improving
water quality.
The nature of aquatic plants
is similar to other types of plants in that they need oxygen for
life and carbon dioxide for photosynthesis. In extremely polluted
water, the oxygen content will eventually decrease and cause the
aquatic plants to die so if we use aquatic plants in highly contaminated
wastewater sources they may increase the polluted content rather
than help to reduce waste in the water. Therefore, when using
aquatic plants to treat wastewater, it is necessary to consider
the amount of oxygen present in that water source. If there is
little or no oxygen content at all, then it is necessary to add
oxygen into the water to save the aquatic plants and assist their
growth. When the plants grow well, they will help to use the excess
nutrients in the water to build more biomass. There are several
ways to add oxygen into the water, such as compressing oxygen
into the water, agitating the water, and causing a whirling movement
in the water. These are ways to enhance the capability for aquatic
plants to grow properly. The plants that can effectively make
use of the nutrients in the water will grow rapidly and possess
strong trunks and roots. It is very important for the roots which
are in contact with the wastewater to develop healthily. Moreover,
the total weight of the plant must increase within a certain period
of time suitable for each type of plant. After taking measures
to make sure the plants grow strongly, then the true process of
wastewater treatment will occur. Aquatic plants growing well in
the various water sources will become important resources which
can be used for other purposes.
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The constructed
wetland waste water treatment system in England. Bricks
are laid across the water way for regulating the level of
water flooding over water tolerant plants and retarding
the water flow.
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In the selection of aquatic
plants for treating wastewater, it is necessary to consider the
area and its condition as the main factor. As mentioned before,
there are different types of aquatic plants. That is, some are
categorized into floating plants such as water hyacinth; some
grow well at the edge of riverbanks or canal banks such as Typha
angustifolia, Conna indica, Cyperus corymbosus Rottob., and Jussiaea
repens Linn.; some live under water such as Hydrilla verticillata,
Blyxa echinosperma Hook.F, Ottellia alismoides(L.) Pers.; and
some have their trunks submerged in water but the leaves remain
afloat, such as lotus, etc. When deciding on the type of plants
to use, it is important to consider the plant's capability to
withstand wastewater and also the convenience in controlling the
numbers of such plants, for these plants can be further used for
other purposes, such as making fertilizer, mats, weaving products,
and handicrafts. Apart from by-product uses of the plants, research
into its other uses are important objectives of treating wastewater
by the water culture method.
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Conna indica
was used for absorbing nutrients in the water before being
released into the pond at Nong Yai Hospital, Chonburi Province.
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Aeration is a way of growing
the plants to be strong and healthy under the absence of substrate.
The use of an aerator will aid the plants to grow well and be
conducive to the wastewater treatment. In case there is no tool
available for checking the quality of the water, it is possible
to detect the level of pollution by noticing the color of the
water and the presence of small living things in the water.
If the color of the water
turns green, it shows that there is oxygen in the water and that
the water source is not harmful. Green seaweed, which is the lower
plant (microphyte) living in the water, is mostly beneficial because
it serves as fish fodder and helps to treat wastewater. There
are not very many types of green seaweed that are dangerous for
living things.
If the color of the water
is found to be greenish blue, it means that there is very little
oxygen content and a high acidity level in that water source.
Many types of seaweed found in such water source are also harmful
to living things, therefore, to use aquatic plants for treating
wastewater, it is necessary to also add oxygen into the water
through an oxidation process, in order to gradually decrease the
acidity content in the water. This is important because most of
the aquatic plants require neutral water conditions to grow well.
For water with black color
and a foul smell, it is very necessary to add oxygen into the
water by letting water whirl slowly so as to prevent the stirring
of dirty sediments. This will help the number of bacteria that
feed on oxygen to increase, and resultantly contribute to the
dissolving of dirty sediments found in the water before finally
using the aquatic plants to treat the wastewater. In this case,
it is possible to use submerged plants such as Hydrilla verticillata
to help remove dirty sediments from the water, but remember that
it has to undergo the process of oxygenation first.
In most cases, wastewater
in slum areas has black color and a foul smell because of the
dense population and habit of discharging wastewater without first
undergoing any treatment. Therefore, health improvement, especially
the wastewater treatment, is too complicated for the people in
slum areas to manage on their own, due to a lack of knowledge
and necessary equipment. Also, these people have been used to
this careless behavior for such a long time that it has become
very difficult to correct. Therefore, community leaders must possess
correct knowledge, understanding, and a strong determination to
work together in solving the wastewater problem. The use of aquatic
plants to treat wastewater is by far a simple and cheap alternative
which can be implemented in a short time, so it is appropriate
to use this measure to help improve the quality of society, despite
the fact that it is just a small community.
Since 1990, the Chaipattana
Foundation, in collaboration with the Royal Irrigation Department
proceeded to improve the water quality in various water sources.
In the initial stage, the Chaipattana Aerator has been used to
improve water quality and allow water to circulate. Later, the
microorganism trap has been applied together with the aerator
to improve water quality and for aerobic microorganisms to cling
to. This system worked as expected.
The improvement of water quality
by using aquatic plants together with an aerator was carried out
at "Nong Sanoe Dredging and Environmental Improvement Project,
Nakhon Ratchasima Province". Nong Sanoe is a large-sized
pond filled with growing weeds. Therefore the water was quite
contaminated and sent a very foul odor throughout the area because
this pond was a receptacle for water discharged from the military
camp and horse stable.
To improve the water quality
here, the pond was dredged at a depth of 2-3 meters and then 5
units of the Chaipattana Aerator were installed. The water quality
improvement system was designed to drain wastewater through the
polishing pond in which aquatic plants were grown before letting
the water flow to the large pond. Part of the large pond has been
allocated as a polishing pond at the dimensions of 8-meters width,
100-meters length, and 0.5-meter depth, where aquatic plants,
namely water primrose (Jussiaea repens Linn.) and water hyacinth,
were grown to treat the wastewater. In the polishing pond, pipes
have been installed for draining the treated water into the large
pond. As a result, water in the large pond was very clear despite
the fact that wastewater was continually released into the polishing
pond.
Therefore under the "Nong Sanoe" Project, aquatic plants
and an aerator were used to improve the water quality under two
implementation patterns.
Pattern 1: System for improvement
of water quality with the use of the aerator and a polishing pond
growing water tolerant plants
According to this system,
wastewater flowed through a grease trap pond which trapped the
grease found in the water. The water was then passed into the
aerated lagoon, where an aerator and microorganism trap may be
installed. The number of aerators and microorganism traps to be
used depends on the amount and condition of the wastewater. Water
passing through the aerated lagoon will be drained into the central
discharged water pond. At this pond, a water pump is installed
to pump water into the polishing pond growing water tolerant plants,
namely Conna indica or Cyperus corymbosus Rottb.. Water is allowed
to inundate the plants at the height of 30 centimeters. The thickness
of the plants helped filter wastewater while the roots absorbed
nutrients in the water, thus improving the water quality. In some
cases, wastewater may be pumped into the polishing pond growing
water tolerant plants without passing through the aerator.
Pattern 2: System for improvement
of water quality with the use of aerator and polishing pond growing
floating plants
This system works by growing
floating plants such as lotus, Jussiaea repens Linn. and water
hyacinth. The depth of the water level in the polishing pond is
about 50-80 centimeters. The width and length of the pond is up
to the predetermined quantity of discharged wastewater. After
conveying the wastewater to the polishing pond growing floating
plants, wastewater will be treated before letting it flow to the
central wastewater retention pond where the aerator is installed,
to allow water circulation and establishment of a balance in the
water source.
This simple system of treating
and improving wastewater by using the proper types of aquatic
plants combined with the aeration led to the achievement of turning
wastewater to become crystal clear. The establishment of this
system also provided knowledge and understanding for the people
so that they will realize the important relation between the environment
and existence of mankind.
