A good evaluation of polymer performance for application in belt and filter presses, in sludge dewatering, will depend on free drainage filtrate volume, filtrate clarity and sludge cake characteristics. The best polymer results would yield the greatest filtrate volume, best clarity, and a compressible dry sludge cake. The experimentally determined dosage may not necessarily be the precise dosage needed on the press, but this dose will aid in the selection process and serve as a starting dosage.

Required Equipment

1. Graduated cylinder 250 mL
2. Bucket for sample collection: 5 gallon capacity
3. Buchner Funnel Apparatus (90 mm dia.), with vacuum port.
4. Fabric screen, like that used in the filter press or Whatman #40 filter paper.
5. Beakers: 250 mL, two
6. Syringes: 1cc, 5 cc
7. Mechanical vacuum pump or connection to laboratory or plant vacuum source.

Test Procedure

1. Assemble Buchner funnel apparatus.
2. Collect 5 gallons of sludge to be tested. This sludge should not have any polymer in it, however, it should contain whatever substances are typical of the system to be treated.
3. Fill the 250 mL cylinder with 200 mL of sludge.
4. Add polymer solution, according to the second dosage chart.
5. Pour this into one of two beakers. Pour back and forth between the two beakers six times. Consistent mixing is important.
6. Start the vacuum on the Buchner funnel and pour the sludge into the funnel
7. Start the timer. Note the filtrate volume at ten second intervals, until the drainage stops. Note the final volume of the filtrate and its clarity.
8. Look into the funnel to observe the cake characteristics. A dull cake indicates a dry cake. As shiny surface indicates a wet cake. Determine the percentage moisture content by weighing the wet cake, then drying it overnight in an oven set at 100 degrees C, and weighing it again.
9. A crude pressibility test can be run by squeezing the cake in one hand. If the sludge is compressible and the runoff is clear, the sludge should run well on the press. If the sludge runs through the fingers, it is not likely to run well on the press.