Is ECD means Electron-capture dissociation. is this technique suitable for removal of sludge. could you please share any relevant materials to study about it.

The sludge does not settle, a simple chemical treatment solution but which does not eliminate the cause, a solution indicated in the process if you manage to regenerate the sludge, through a stronger aeration.

Nicolae Ion thanks for your answer. could you please elaborate about the chemical treatment solution. do have any recommendations for chemicals.

CaOCl2 (calcium hypochlorite), but it is a solution at the moment.

Dear https://www.researchgate.net/profile/Mohammed-Abdul-Ashrath

There seems to be some confusion here. Apparently Nicolae assumes that your clarifier is part of the biological treatment downstream of the aeration basin.

However according to your description, this clarifier is downstream of a physical-chemical treatment: oil removal, pH control and coagulation-flocculation.

Hence the solutions suggested by Nicolae will work only for aerobic biological sludge not for physical-chemical sludge.

Most likely the floating sludge in your case is due to residual oil. In that case, a dissolved air floatation (DAF) clarifier with surface sludge removal instead of a gravity settling clarifier would be recommended. Alternatively you may need to upgrade your "advanced oil treatment" (what kind of system?) to include upstream emulsion breaking. Either way I would recommend to start by sampling your floating sludge and analyzing its total oil (free + emulsified) content.

Thank you Bruno, your observation is correct.

Bruno Peeters

Indeed you understood very well. plant is desined to handle oily wastewater where we use advance oil separator technology, unfortunately system has issues with filter clogging which couldn't take incoming capacity. temporarily we installed submersible pump to pump out the water to pH adjustment tank. following process is same as pH adjustment - treating with PAC & polymer - sent to clarifier.

Due to untreated oily waste still present which causing problem of floating sludge/scum in clarifier. now I am looking solution for removal of floating sludge.

Soon we will fix the AOS (filter clog) to have smooth operation.

As per your suggestion, i have limited choice to change type of clarifier unit.

I request, from your experience, if you could suggest me some chemical or other treatment to resolve the issue. or maybe you could please give me some reference material to study.

mohammed abdul Ashrath

We never use a filter system on oily wastewaters precisely because of clogging.

Instead we use an API oil separator with oil skimmer followed by a DAF unit if needed.

I have no special suggestions to add additional chemicals for oil removal. However we do recommend to perform so called jar tests with suitable chemicals and varying dosing rates at different pH especially to break oil-water emulsion (usually in acid conditions) upstream of oil removal if this would apply to your case (no info).

Bruno Peeters

Noted, thanks for your valuable info.