. INSPECTION AND MAINTENANCE
Graf UK Ltd
INSPECTION AND MAINTENANCE
5
5.3 Determination of Sludge Removal
In order to determine the need for sludge removal in the wastewater treatment system, a settling test should be carried
out at maintenance intervals. For this settling test, the SV30 is measured. The SV30 is the sludge volume occupied by
1000 ml of activated sludge after a settling period of 30 minutes. It is a measure of the amount of sludge present in the
wastewater treatment system.
Measurement of the SV30 is carried out in a 1000 ml graduated cylinder.
The following points must be observed during this measurement:
A. Turn ventilation on - if not active - and allow to mix for a short time
B. Submerge the scoop into the tank and remove sludge sample
C. Fill the graduated cylinder with the sludge sample up to the 1000 ml mark
D. Let the cylinder containing the sample stand in a place free from vibrations for 30 minutes
E. Read the sludge level and carry out sludge removal if this is > 900 ml/l
5.4 Sludge Removal
Removing sludge from the wastewater treatment system should be carried out according to the following points:
F. Remove the cover
G. Remove the deposits on the water surface and on all visible surfaces (bae, sample container, siphon)
H. Wash down the visible surfaces
I. Insert the suction hose into the wastewater treatment tank until it reaches the floor
(CAUTION: air admittance valves on the ground must not be damaged!)
J. Aspirate until about 30 cm of wastewater and sludge remain in the wastewater treatment system
K. After emptying the tank, you should refill the tank with fresh water again so the tanks is two thirds full.
5. Inspection and Maintenance
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5.3 Determination of Sludge Removal
In order to determine the need for sludge removal in the wastewater treatment system, a settling test
should be carried out at maintenance intervals. For this settling test, the SV30 is measured. The SV30 is
the sludge volume occupied by 1000 ml of activated sludge after a settling period of 30 minutes. It is a
measure of the amount of sludge present in the wastewater treatment system.
Measurement of the SV30 is carried out in a 1000 ml graduated cylinder.
The following points must be observed during this measurement:
6. Turn ventilation on - if not active - and allow to mix for a short time
7. Submerge the scoop into the tank and remove sludge sample
8. Fill the graduated cylinder with the sludge sample up to the 1000 ml mark
9. Let the cylinder containing the sample stand in a place free from vibrations for 30 minutes
10. Read the sludge level and carry out sludge removal if this is > 900 ml/l
11. After emptying the tank have to be filled up with fresh water again
5.4 Sludge Removal
Removing sludge from the wastewater treatment system should be carried out according to the following
points:
7. Remove the cover
8. Remove the deposits on the water surface and on all visible surfaces (baffle, sample container,
siphon)
9. Wash down the visible surfaces
10. Insert the suction hose into the wastewater treatment tank until it reaches the floor
(CAUTION: air admittance valves on the ground must not be damaged!)
11. Aspirate until about 30 cm of wastewater and sludge remain in the wastewater treatment system
Fill the graduated
cylinder with the
sludge sample up
to the 1000 ml
mark
30 minutes
Read the sludge
level an carry out
sludge removal if
this is > 900 ml/l
Fill the graduated
cylinder with the
sludge sample up to
the 1000 ml mark
Read the sludge level
and carry out sludge
removal if this is
> 900 ml/l
k
30 minutes
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