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topic 3371

Selection of filter cloth for filter press for wastewater treatment sludge


Is there any literature available for the selection of cloth materials used in plate & frame filter presses? How can I determine the best fabric mesh size for an application?

Rick Alexander
engravers - Gaffney, South Carolina


Vendors of the filter cloth may have a few selections, but the last time I replaced some, there was only one choice for the filtering of sludges from a metal finishing operation.

The particles tend to blind up the mesh rapidly, but if you have some bleed-through, you can add a few parts/million of polymer to help lower suspended solids after filtration.

tom pullizzi monitor
Tom Pullizzi
Falls Township,

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We have started running a filter press on our pH adjusted wastewater, containing mostly Ni. At pH about 10.5-11.0, we form a decent amount of precipitate, which sort of goes through the filter-press cloth instead of staying on it. Is there a particular cloth weight/density or whatever measure is commonly applied here, that works well on hydroxides, or would it be advisable to use a filter aid, flocculent or some other technique to prevent the breakthrough? Thanks

berl stein
berl sig
"PlaterB" Berl Stein
NiCoForm, Inc.
supporting advertiser
Rochester, New York



I think you need to generate a larger particle size. The filter press cloth is probably quite coarse and most unflocculated metal hydroxides are pretty fine. You should be able to see the flocs form as the flocculating agent mixes in. Just don't overdose as it will turn the sludge into a slimy mess. Almost any industrial chemical supplier can provide the flocculating agent, probably an anionic agent will work best. Do a jar test first (waste sample in beaker, very small amount of agent added per manufacturer's dosing rates, mix and voila! flocculated sludge). Jar tests are good for evaluating different types/manufacturers. You may even get enough in the samples to do the whole job!  

bill vins
Bill Vins
microwave & cable assemblies
Mesa (what a place-a), Arizona 


In regards to the nickel hydroxide precipitate, I would definitely use a filter aid such as diatomaceous earth to precoat the cloth. This should prevent leak through of the precipitate.

Rocky C. Costello, P.E.

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