River water sedimentation with PAC and PAM
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Dear teachers: I would like to ask why, when PAC and PAM are used in inclined tube sedimentation tanks, the water appears clearer, but loose flocs remain on the inclined tubes and do not settle; instead, they float to the surface, where white gel-like substances also appear! Request for assistance! :dizzy:
Loose flocs remain on the inclined tubes and do not settle because there is a distance between the upper end of these tubes and the water surface. The fine sludge particles that have not settled inside the tubes continue to settle in this space, and the settled sludge remains on the surface of the inclined tubes. This accumulated sludge needs to be removed manually (it can also be removed using a siphoning method); otherwise, an increasing thickness of sediment may damage the inclined tubes. It is also necessary to check the dosage and ratio of PAC and PAM – based on your description, it seems that either the amount of PAC and PAM is insufficient or their ratio is not appropriate
It doesn’t seem to be sludge; when something is used to stir the flocs on the inclined tubes, they float to the surface, and the water on the surface contains some white colloids
It doesn’t seem to be sludge; when something is used to stir the flocs on the inclined tubes, they float to the surface, and the water on the surface contains some white colloids
If there is sludge at the upper part of the inclined tubes, it is relatively light in weight and feathery in texture; the fermentation of organic matter produces substances similar to white feathers, which generally float on the surface of the water.
Moreover, when you use your hand to push the water on the surface aside, it quickly comes back together again; it’s as if oil has been mixed into the water, with the water’s surface appearing covered by a layer of dust
It may be caused by an excessive dosage of PAC or PAM chemicals; it is necessary to calculate an appropriate dosage and clean out the debris at the top in a timely manner, otherwise it will affect water quality. It is recommended to install a scum skimmer.
The white gel-like substance is likely due to incomplete dissolution of PAM; loose particles remain on the inclined tubes and do not settle. I suspect that the PAM has lost its effectiveness and can no longer facilitate flocculation and sedimentation.