RE: DIG-L: Viscosity of sludge in Digesters

["Schomaker, Ton" <t.schomaker@royalhaskoning.com>]

Dear Sylvaine and Thirtha,

We have some rheology data of sewage sludge at WTTP Nijmegen.


		     undigested sludge			      digested
sludge	
 shearing rate	 shearing stress	viscosity	shearing stress
viscosity
(1/s)		(Pa)		(Pa.s)		(Pa)		(Pa.s)
				
0,00221 	0,544 		246,15 		1,088 		492,31 
0,06144 	0,816 		13,28 		1,36 		22,14 
0,17105 	0,979 		5,72 		1,632 		9,54 
0,47515 	1,088 		2,29 		1,632 		3,43 
1,326 		2,176 		1,64 		2,176 		1,64 
2,873 		2,72 		0,95 		3,264 		1,14 
7,956 		3,808 		0,48 		4,352 		0,55 
10,2544 	3,808 		0,37 		4,624 		0,45 
17,1054 	4,352 		0,25 		5,44 		0,32 
47,515 		5,984 		0,13 		6,528 		0,14 
98,05 		7,7 		0,08 		8,515 		0,09 
132,6 		8,704 		0,07 		9,248 		0,07 

These data indicate that:
- difference in viscosity of digested and undigested sludge is rather small;

- at shearing rates in the range above 10 1/s mixing is efficient since 
apparent viscosity of both types of sludge hardly changes at increasing
shearing rates.
 
Hope these data give some answer to your question.

Regards,

A.H.H.M. (Ton) Schomaker MSc
Division Water
Advisory Group Water Resources & Ecology

Haskoning Nederland B.V.
a company of Royal Haskoning
P.O. Box 525
5201 AM 's-Hertogenbosch
The Netherlands
Tel.: +31 (0)73 687 41 86
Fax:  +31 (0)73 612 07 76
Mobile: 06 104 107 26
E-mail: t.schomaker@royalhaskoning.com
Internet: www.royalhaskoning.com

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-----Original Message-----
From: Sylvaine BERGER [mailto:sylvaine.berger@solagro.asso.fr]
Sent: vrijdag 26 april 2002 9:22
To: digestion@crest.org
Subject: DIG-L: Viscosity of sludge in Digesters


hello all ,

mr Tirtha Ghosh ask me for a question about the viscosity of the sludge. Has
someone some  values about the viscosity before and after the anaerobic
digestion ?
Thank you

Sylvaine Berger


Dear Sir/Madam,
I am a Chemical Technologist working in an
Environmental Engineering & Consultancy Firm (Geo.
Miller & Co. Ltd.) in India. I have come across a
question for which I am not getting any answer in the
literatures available to me. If possible will you
please help me to sort out the problem? My query is as
follows??

In Sewage Treatment Plants we mix sludge in Digesters.
The mixing may be diffused aeration or surface
aeration or mixing through submerged agitators. I want
to know the viscosity of the sludge in the digester.
Are there any drastic change in the viscosity of the
sludge that is coming into the digester and the one
going out? If it is so then please furnish me a
comparison between the two.

I hope I will get a sharp and positive reply from your
side.

Thanks and Regards
Tirtha Ghosh
(Project Engineer)
e-mail---- tgburo@yahoo.com


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