Dear Jose Carlos

Tell me please, from where did you take the wastewater sludge? I meant which tank? Aeration tank? Final clarifier? Thickener? Tell me in details, as you can not thicken it more. Also what was MLVSS?

Regards

Maybe decantation or filtration?

I am not sure that "AD" is but generally it should be possible to concentrate activated sludge to 10-20 g/L by leaving it for some hours and decant the supernatant away as Marta also suggest. If the sludge doesn't settle well it can be "aided" by adding e.g. CaO or AlCl3.

Hello Jose Carlos Nogueira Filho,

We use mechanical fast "table" thickeners based on gravity filtration on a rotating filter band after adding some polymer. On mixed sewage sludge we get up to 100 gDS/L (DS = dry solids) to feed to the sludge digesters. This increases the capacity of these digesters by up to 300%.

Hi, Jose.

That's dependent on the solids content you want to achieve.

You can first put the sampled sludge in the lab for one night before use. Then the next day discharge the supernatant or liquid, and use the remaining part for centrifugation if you want to get a high solids content.

Hi everyone,

thank you for your inputs. Overnight decantation doesn't really help much as the supernatant accounts less then 10%, which increases very little the Total Solids content. But using it with centrifuge sounds the most efficient way to go as Zhongfang Lei suggested. I will also consider using a large container .

Thank you all again,

Best regards,

Jose

If the sample is collected from the final clarifier, in two hours of detention time, 90% of the solids will settle. You can decant the supernatant and go for centrifugation of the settled sample. Using centrifuge apparatus, solids concentration can be increased in few minutes.

Best wishes

Use polyacrylamide floculant in concentration 5-10 mg/g TS followed by gravity decantation or centrifugation.

I will suggest separator funnel with 1 to 2 hours dementation time.

Treatment of sewage sludge (SS) by biodegradable polyacrylamide-based flocculants (PAM) is considered to be an effective way to increase total solids (TS) content prior to anaerobic digestion (AD).

Please refer to a recent publication from our group

"Influence of cationic Polyacrilamide Flocculant on high-solids anaerobic Digestion of Sewage Sludge under thermophilic Condition"

Environmental Technology DOI 10.1080/09593330.2017.1417492

I think that you can use very slow mixing in a container because gas babbles that produced in anaerobic condition rise sludge and mixed them. Using very slow mixer In gravity thickener causes gas babble release and sludge will be thickened.

Best regards