Sludge Viscocity

[MadChemist]

Hi all,

I'm a process modeller working in the UK water industry. I'm looking at pre-pasteurisation technologies, which involve cooking the sludge up to 70 degC! The problem is that I don't know what happens to the laminar and turbulent velocity functions at such a high temperature! My worry is that the sludge will turn marmeladey and block up the heat exchangers / pipework and be really viscous! Does anybody know of a reference paper on viscocity of hot sludge? The old WRC TR185 (1983) equation is only valid up to 25 degC!

Cheers

MadC

 

[Chris73]

What is the solids content rate of your sludge? If it is not kind of a thickened sludge - let's say up to 1% solid content - I would go with standard water viscosity.
Vkin (kinematic viscosity) of water:
@ 60^C = 4.78 * 10^-7 m^2/s
@ 80^C = 3.66 * 10^-7 m^2/s

Usually sludge doesn't get thick if warmed up, not until 100^C (of course!), quite the contrary happens - it gets less viscous! Good luck!

 

[stanier]

You might try Mono or Seepex pumps in Eurpoe where they routinely pump sludge. The problem I see is that the characteristics of the sludge will vary from primary to anaerobically digested sludge, is scum mixed with the sludge, the types of fats and greases, is there any industrial waste at the site.

Suggest you may need to do somework on the sludge in your domain and research the data you seek.

A paper by Hisashi Murakami, Hideaki Katayama & Hidetsugu Matsuura covered a great del of information but this was all at 20 C. They may have or know of other researches who have datat that you seek. Good luck.