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Waste water treatment is one of the
biggest problems of our modern society. Water is indispensable for the
industry and also for the population living in ever growing cities. As
fresh water resources are becoming shorter and shorter it becomes a must
to clean the water used by the industry or for civil purposes before
putting it back into the natural circle.
First of all it must be clear that products for waste water treatment
can only be used if there is a treatment plant.
There are two major categories of water treatment plants and precisely
the plants for chemical-phisical treatment and the biological ones.
Generally speaking, we can say that chemical pollution is eliminated
with chemical treatment, whereas pollution from organic materials must
be eliminated with a biological treatment.
The chemical treatment is carried out in order to precipitate heavy
metals and suspended solids and generally consists in the adjustment of
pH and in the dosing of iron or alluminium salts and the consequent
precipitation of hydroxides.
In the biological treatment, organic substances are oxydized and
mineralized in presence of particulare species of bacteria.
In some important plants there is also a so called third stadium in
which phosphates are eliminated. Also in this case the treatment is with
addition of iron or aluminium salts.
In all these treatments there is a production of precipitate or sludge
that must be eliminated and this may happen by burning it, discharging
it or in less most fortunate cases reutilizing it. In any case the
sludge must be concentrated or dewatered and these process is carried
out with mechanical devices as centrifuges, belt presses or chamber
presses.
SESN products can be used in all the mentioned treatments and they are
often very important to improve the yield and the duration of the
process.
Hereafter we report the most important SESN products for the different
treatment:
CHEMICAL TRETMENT PLANTS
Tillflock PR 6
It is an interely organic cationizer and coagulant that can
substitute, al least partially the inorganic salts (polyaluminiumchloride
and iron chloride). With its action of ionic exchange, Tillflock PR 6
coagulates suspended substances without the formation of of metallic
hydroxides. The sludge volume will in this way remarkably decrease with
important savings in the sludge digestion or discharging. Tillflock PR 6
also has a relevant decolourising action.
Tillflock PR 6 PA
It is a product with similar characteristic of the above reported,
but with a mixed organic/inorganic nature. It has the advantage that,
particularly in small plants, it can be used as unique coagulating and
flocculating agent.
Nexflock AP 40
It is a solid anionic polyacrilamide normally used in strongly
diluted aqueous solutions in order to increase the flock dimension and
accelerate the sedimentation speed, particularly of metallic hydroxides.
Nexfoam AS1 and AS2
Defoamers with a very wide action spectrum
BIOLOGICAL TREATMENT PLANTS
Tillflock PAAM 20
It is a liquid polyacrilamide that can be used to accelerate the
sedimentation of biological sludge in case of particular problems
(bulking) or for underdimensioned plants.
A possible use of Tillflock PAAM 20 is in the organig sludge thickening
before sending it to anaerobic digestors in order to diminish the sludge
volume and to increase the stay in the digestors increasing in this way
their yield.
Nerflock CP 30, CP50, CP 70
Solid cationic polyacrylamides used as conditioning agents in the
mechanical dewatering of organic and mixed organic/inorganic sludges.
Nexfoam AS 1
Defoamer with a very wide action spectrum. It is biologically
degradable and, properly used, does not influence the bacterial life of
the plant.
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