5.3.2.1 Settling test
If sludge is removed using a
vacuum truck, the sludge amount
is determined with a sludge settling
test in the process tank every two
months. A one-litre measuring
glass has been supplied with the
treatment plant for the settling
test.
The settling test should be done
when the treatment plant process
is in the continuous aeration phase.
A text on the PLC display indicates
the ongoing process phase and its
start time.
If some other process phase is
going on in the treatment plant
(see process phases in section
4.2), the settling test result is only
indicative. If the sludge level in the
measuring glass is above 500ml
when the settling test is taken into
sleep mode, repeat the test within
one week. Aeration must be on
also in sleep mode. You can start
the compressor by moving the X3
plug into the X6 socket. Remember
to move the plug back to its place
aft er the settling test!
When the treatment plant is in the
settling or emptying phase, wait a
few hours before taking the test.
Testing instructions:
1.
Check the process phase from
the PLC display.
2.
If a phase other than conti-
nuous aeration is going on in
the treatment plant, ensure
that aeration is on by moving
the X3 compressor plug
into the X6 socket. Wait 10
minutes for the sludge to mix
evenly in the tank.
3.
Wear protective gloves when
taking the settling test!
4.
Take sludge from the process
tank on the right side into
the measuring glass up to the
one-litre marker (picture 40).
5.
Place the measuring glass on
an even surface (temperature
above 0 degrees).
6.
Aft er 90 minutes, check the
clarifi er and sludge separation
surface (picture 41).
7.
If, aft er 90 minutes, the slud-
ge surface in the measuring
glass is above 500ml and the
sample has been taken in the
continuous aeration phase,
you need to order the vacuum
truck.
8.
Move the compressor plug
back to its place.
9.
Lock the treatment plant
cover.
NOTE! Note the risk of falling into
the tank!
5.4 Sampling
Sampling should be performed
by professionals. The clean water
sample can be taken from a
purpose-fi tted sampling well, the
discharge location of the plant, or
the top part of the process tank
(at a maximum depth of 0.2 to 0.3
metres from the water surface) at
the end of the settling stage, 5 to
10 minutes before emptying.
The process start time can be
determined for sampling purposes.
The desired process start time is
entered in the operation settings
of the PLC by using process
block (see section 4.3 table). The
process block operates so that the
treatment plant gathers the batch
but does not start the process until
the set time. The process starts at
the set time if a suffi
cient amount
of water has been provided for
the batch. The pump-out starts
aft er approximately 7 hours and 30
minutes from the set time. Make
sure that the logic clock is on time!
Contact the manufacturer in
matters related to sampling.
Picture 40
Picture 41
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