CLEAN RECYCLING OF SYNTHETIC MATERIALS
For effluent treatment, plastic films recycling companies rely upon ACAT equipment including screw press, ACAT know-how and ACAT as a competent equipment supplier for new
systems.
To counteract horror scenarios as they were
shown in the documentary film “Plastic Planet”, innovative companies made it their business to produce high-grade plastic granules
from collected plastic waste. The pellets are
further processed into films or bags. Plastic
films are delivered in bales and after a rough,
manual waste sorting procedure, the material
is crushed in mills and washed. Before drying
it is processed into pellets in the extruder. The
washing water resulting from the washing
process is roughly screened. In the past this
water has been directly pumped via exfiltration into the sewer system after several cycles. The company were aware that this
method was not very efficient and in February
2011 the general manager of the company
contacted ACAT to develop a facility for their
waste water treatment.
Because of the high amount of water (3.500
m³ per month) and the high grade of pollution
(more than 2.000 mg/litre COD (limit 800
mg/litre) at clean water costs of € 0,64/m³
and waste water costs of € 1,27/m³ - the construction of a new sewage treatment plant
was the most reasonable solution.
Trials on site with different polymers showed
that with powder polymers and a new sewage
treatment plant the required limits were ensured and that the best dewatering results
were achieved with a screw press.
AUTHOR: CHRISTIAN KOZANDA
Trials on site with different polymers
showed that with powder polymers
and a new sewage treatment plant the
required limits were ensured
In March 2011 the order was given to ACAT to
build a new sewage treatment plant alongside
the old one with a capacity of 100 m³/h, including the entire machine system with all the
required piping, pumps, measurement and
control technique as well as the switch and
control system.
Article from: inside acat 15/2012, page 1 of 4
CLEAN RECYCLING OF SYNTHETIC MATERIALS
Plastic films are delivered in bales and after a rough, manual waste sorting procedure, the material is crushed in mills and washed. Before drying it is processed into
pellets in the extruder
In two existing sewage pumping stations all
process wastewater is collected and then
pumped over a new water quantity measurement into the new waste water treatment
plant built above the ground.
The plant is built in such a way, that the waste
water flows down through the plant with a
free gradient and the purified water flows
through gravity pipes into two pumping stations for potable water located in the production hall.
AUTHOR: CHRISTIAN KOZANDA
From wastewater to pure water
The first step in waste water treatment is the
mechanical removal of heavy ingredients like
sand or metallic parts with a grit grader with
spiral discharge. At the input of a tube flocculator the polymer solution is added. The dosage depends on the measured influx capacity.
If needed a neutralization agent or detergent
can be added. Then the waste water is sent to
the dissolved air flotation plant that is made
of stainless steel (content about 80 m³). Here
Article from: inside acat 15/2012, page 2 of 4
CLEAN RECYCLING OF SYNTHETIC MATERIALS
air pressure is added to a part of the
wastewater through the recirculation pump.
At the inlet he water is enriched with air and it
is supplied again to the waste water flow. In
the flotation basin the added air rises and
promotes the formation of floating substances on the surface of the water, where the flotation sludge is drawn off continuously with
two flight scrapers. At the same time sludge is
accumulating at the bottom of the tank container. Both, flotation sludge and bottom
sludge are removed discontinuously with
pneumatic slides and transported through
gravity pipes to a stainless steel tank. For dewatering it is further conveyed with eccentric
screw pumps to a stainless steel storage tank,
which is fitted with an agitator.
Over an overflow weir the treated wastewater
leaves flotation and through gravity pipes it
flows to the two potable water pumps and is
returned to the production cycle. As soon as
they are full the incoming water is transported to an additional surface
buffer tank.
throughput rate of > 150 kg dry substance / h.
In November 2011 the plant was handed over
to the customer and it is operating continuously 7 days per week and 24 hours per day.
To the owner's complete satisfaction the
specified discharge values (COD currently 623
ml/l) as well as the low maintenance efforts
(support via calls to Vienna) and the reduction
of water consumption (less than 800
m³/month) were achieved from the very beginning.
Due to this fine success we received a further
order for the complete machinery equipment
with two ACAT screw presses AS 0505 S, two
screening machines and a grit separator for an
Austrian plant in November 2011.
In 2007 we supplied a system for thickening, a
grit separator and two screening machines to
a branch of this company and they are still
running without problem, proving the competence of ACAT. Everything is in one hand:
plant installation, equipment, assistance and
supply of operating material.
Sludge treatment
The sludge is further processed with an ACAT
screw press AS 0505 S. Screw presses ensure
that filtrate water from the drainage process
can be returned to the potable water pumps,
because it becomes very clean. The sludge is
dewatered up to 45 – 60% dry substance and
disposed in troughs. With a driving power of
0,75 kW and a speed of < 1 U/rpm the ACAT
screw press AS 0505 S ensures minimum
power consumption and minimum wear at a
AUTHOR: CHRISTIAN KOZANDA
Article from: inside acat 15/2012, page 3 of 4
CLEAN RECYCLING OF SYNTHETIC MATERIALS
The sludge produced is dewatered with an ACAT screw press AS 0505 S.
AUTHOR: CHRISTIAN KOZANDA
Article from: inside acat 15/2012, page 4 of 4