|
|
|
| Improving the treatment capacity of the lagoon by installing MiraCarbon! |
Improving the functions of the lagoon's treatment facilities
What is the lagoon method？
Lagoon method is a water treatment method that purifies the water by itself,
by using the cleansing action of nature in a man-made lagoon. This method
uses an irrigation pond which is shielded and waterproof called lagoon
(pond for stabilization), where as the sewage, waste water, livestock waste
water and etc are treated in a certain period of time.
In this method, the treatment depends on the difference of water depth,
if there is an oxygen or no oxygen supply. It has many variations and treatment
features such as facultative aerobic, facultative anaerobic, aerobic type
and anaerobic type lagoons. It is being used in many sewage treatment facilities,
mostly on developing countries and currently being used in Japan for livestock
waste water treatment.
 |
 |
| Inflow of polluted water into lagoon |
Aeration lagoon |
The mechanism of lagoon treatment facilities
Generally, a lagoon has 1.5m～2.5m water depth. The aerobic treatment is
done in the upper layers near the surface and the anaerobic treatment is
done in the lower layers. Generally the period of time is from 5～30 days,
the algaes on the upper layers will breed and photosynthesis from the algae
will supply oxygen. Aerobic bacteria will generate from the oxygen supply
of the algae and decompose the organic matter in the flow of waste water.
And since the sunlight can not reach the lower parts, photosynthesis is
not performed. Organic matter as material which has high settleability
of wastewater deposit is decomposed slowly by anaerobic fermentation. This
treatment will progress with longer period of time, then the treated water
is released.
Recently, in the waste water treatment plants on developing countries,
the treatment effect is improved by taking longer period of time and the
treatment is performed in various "facultative pond" combinations
with aerobic and anaerobic functions. The treated water is then released
on the rivers.
 |
| Idea of the lagoon method |
 |
Basic concepts of the lagoon method treatment plant
|
Advantages and Disadvantages
The lagoon treatment method uses the natural purification mechanism of
nature. The treatment is easy, made possible by the retention ponds but
it has various disadvantages.
■ Advantages:
１．Low-cost treatment because it does not require special equipments, chemicals
and driving power.
２．It does not require technical experts for daily maintenance and control.
３．It can be easily introduced and install in areas even with cheaper processing
cost.
■Disadvantages:
１．Since it uses the purifaction mechanism of nature, we can not expect
high treatment effect on water quality.
２．Large area is required for oxidation ponds since the lagoon is large
and shallow.
３．The decomposition of organic matter is slow and when oxygen is not sufficient,
it will become anaerobic that generates the malodor.
４．When the sludge has accumulated, the treatment capacity on the oxidation
ponds will decrease, the period of time needed will be shorter and the
treatment will be insufficient.
Installation of MiraCarbon
■ Location:
Lagoon should be installed appropriately with the oxidation pond. It will
be most effective when it is installed evenly in the entire area. And when
it is difficult to install large lagoons, it is necessary that the treated
water pass through the last sedimentation pond before the treated water
is released.
■ Types:
Lagoons：oxidation ponds has a water depth of 1.5 ～2.5 . In the lagoon with calm water flow and since it requires longer of period of time, the tassel type MiraCarbon should be installed. Around the aeration device, MiraCarbon textile type and lattice type should be installed.
■ Methods:
There are various methods to install the MiraCarbon on large lagoons. Materials
are required for fixing. The appropriate installation method is the combination
of frame unit and rope hanging unit.
■ Amount:
Lagoons needs a long period of residence time in the oxidation ponds. So
the amount installed is the standard of the installation amount on lakes
and marsh. The amount of CarbonFiber to be installed is 10～100g/㎥ per capacity.
 |
| Schematic view of MiraCarbon installation for lagoon treatment facility |
|
