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Filter press stops at half full

The filter press pumps hard as if it was full when I pre-coat it. Also, when I open it, it is only half full. Good solid cake, just half full. What do I need to do or look for to fix this problem?

Armando Rodriguez
- Piti, Guam, U.S.A.
July 6, 2008

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July 8, 2008

Hi, Armando. Apparently your filter cake is so heavy and impervious that you just can't pump any more liquid through it. But what may help at least somewhat is to discharge compressed air through the filter plates (with the press still closed), which knocks the cake away from the cloth. This should allow at least some liquid to get between the cake and the cloth. If what you are filtering is so fine that filter aid is mandatory though, you may find that the filtrate is not clear enough for discharge and must be run back to the feed side (depends on whether you are using the press solely to collect sludge, or also to clean the filtrate). Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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Armando

If the waste stream feeding the filter press has not changed, look at some form of plugging of the filter clothes. As the filter cloth becomes fouled, it will retrict smaller particles and plug faster than normal. An occasional pressure wash can help.

If the waste stream is not stable, and you have varying sizes of flakes from the sedimentation process, the smaller flakes will compact more than larger flakes, leading to your situation.

Ted's advice works if you are not near capacity on your waste water flow, and have time to manipulate the system.

We have found that when there is an upset, it may take several days to purge the system of the smaller flakes. Look at adding coagulants as needed to produce larger flakes.

Willie Alexander
- Colorado Springs, Colorado
July 11, 2008