The water output from the filter press is extremely low
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Currently, beverage wastewater with acidic properties is being treated by flocculation and sedimentation. First, add Ca(OH)2 to adjust the pH to around 9; then, add PAC and PAM in the flocculation tank, after which the mixture enters the sedimentation tank. The sludge-water mixture is then sent directly to the filter press. At the moment, the filter press is producing a decent amount of water; after about ten minutes, the volume of water produced is reduced by roughly half. Another ten minutes pass, and then almost no water is output anymore. If the slurry mixture is not fed directly into the filter press, but is allowed to sit for about forty to fifty minutes first before being sent to the filter press, it will work much better. The retention time in the sedimentation tank is about one hour. I hope the experts here can analyze what’s going on.
I want to know that too; who can explain it?
It takes some time for PAC and PAM flocculants to cause flocculation.
What was said on the 3rd floor makes sense; it takes some time for the coagulant to react with the suspended solids in order to form sludge. How often should the sludge in the sedimentation tank be removed? It is recommended to allow the sludge to stay in the sedimentation tank for a longer period before filtering it, or one could try replacing the filter cloth of the filter press with a single-filament filter cloth or one that is thinner than the current one. The residence time can be tested on-site; staying for a few hours has no impact on sedimentation and still yields good filter pressing results ； You can contact the filter fabric manufacturer and describe the properties of the sludge, the chemicals used, as well as the existing problems, to see if they have a more suitable filter fabric.
Check whether the mesh size of your filter cloth and the pump selection are appropriate.
Optimize by considering various factors affecting filtration. View the filtering equation.
Based on your description, it doesn’t seem to be a problem with the filter; rather, it’s the sedimentation tank that isn’t functioning as expected, which causes the filter to become overloaded. It is recommended to look for the cause in the sedimentation tank.
Has the original poster found the actual reason? The analyses from the people above are quite good. It seems that the poster used a multifilament filter cloth, and the time allowed for the use of the coagulant was insufficient, which led to the filter cloth getting clogged and as a result, the water flow slowed down.
In the initial stage of feeding into the plate and frame machine, a large amount of water is discharged; once the chamber is filled and the pressure reaches its maximum value, the amount of water discharged begins to decrease. Personally, I believe that the amount of water produced is related to the amount of material fed in and to the filtering efficiency. Since the volume of the filter press chamber remains constant, and assuming the filtering efficiency does not change, theoretically, throughout the entire filtration process, regardless of how much water seems to be produced in the early or later stages, the final level of dehydration will be the same.