SLUDGE DEWATERING - SNF Group
SLUDGE DEWATERING - SNF Group
SLUDGE DEWATERING - SNF Group
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14<br />
d y n a m i c t h i c k e n i n g<br />
S L U D G E D E W A T E<br />
3.3. Thickening drum, screw drum:<br />
The principle is identical to the gravity belt: sludge conditioning with a flocculant,<br />
liberation of intersticial water in the sludge, gravity drainage of the free water through a grid.<br />
In the case of the screw drum, the only difference is that the sludge conveying is done with<br />
an Archimedean screw.<br />
3.3.1. operating principle:<br />
3.3.2. Sludge conditionning before thickening drum:<br />
KEY<br />
PARAMETERS<br />
LAB PROCEDURE/<br />
SPREADSHEET<br />
RECOMMENDATIONS<br />
1<br />
Sludge<br />
+<br />
Polymer<br />
2<br />
● Drainage speed<br />
● Shear resistance<br />
● Filtrate quality<br />
● Floc formation speed<br />
Laboratory evaluation<br />
for belt press<br />
and gravity belt +<br />
Laboratory evaluation<br />
for centrifuges<br />
1<br />
Filtrate<br />
Variable speed flocculator<br />
LAB TESTS PLANT TRIALS<br />
Laboratory trials -<br />
Gravity belt<br />
& Belt filter +<br />
Laboratory trials -<br />
Centrifuge<br />
● Select the best charge density for<br />
the sludge.<br />
● Select the molecular weight best<br />
suited for drainage.<br />
2 Cleaning ramp<br />
● Sludge flow<br />
● Polymer flow<br />
● Injection points<br />
● Screw speed<br />
● Grid cleaning<br />
● Thickened sludge concentration<br />
● Filtrate quality<br />
/<br />
Thickened<br />
sludge<br />
Gravity belt<br />
& Belt filter<br />
performance sheet<br />
● Polymer dosage should be between<br />
3.0 and 10.0 kg/Dry Solids<br />
Tonne (6 and 20 lbs/DT).<br />
● Check the thickened sludge<br />
quality.
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