Re: FW: DIG-L: sewage sludge digestion

["AHHM Schomaker" <ts@HASKONING.nl>]

Dear Maria Elena,

At this moment we believe that in general terms internal heat 
transfer using water as the heat transfer medium is the best 
solution for heating the digester contents. For your case installing 
a hot water heating system in the digester wall combined with a 
solar energy heat transfer system (on the digester roof ?) might be 
a good solution.

What is your opinion on this solution ?

Kind regards,

Ton Schomaker


From:           	"Hidalgo, Maria Elena" <mehidalgo@ceit.es>
To:             	"'ts@HASKONING.nl'" <ts@HASKONING.nl>
Subject:        	FW: DIG-L: sewage sludge digestion
Date sent:      	Tue, 22 Feb 2000 16:20:14 +0100

> I'm very interested in joining  this discussion list. I'm going to work in
> an project that consists of studying the improvement in the digestion of the
> sludge from a small wastewater treatment plant in Navarra (Spain) by heating
> the sludge by solar energy. The digestion currently takes place at room
> temperature. I'm looking for the best system for heat transfer and for
> reducing heat losses and I think that this matches with some of the aims of
> this discussion group.  
> 
> Thank you very much.
> 
> Mª Elena Hidalgo Pérez [mehidalgo@ceit.es]
> Environmental Engineering Section
> CEIT
> San Sebastian
> Spain
> 
> 
> -----Original Message-----
> From: AHHM Schomaker [mailto:ts@HASKONING.nl] 
> Sent: martes 22 de febrero de 2000 10:40
> To: digestion@crest.org
> Subject: DIG-L: sewage sludge digestion
> 
> 
> Sewage sludge digestion in The Netherlands is still based on 
> CSTR-technology from the early nineteenseventies: mesophilic 
> digestion at 32 °C with gas-mixing and external heat-exchange.
> Most digesters suffer from, amongst others, problems with floating 
> layers resulting in high maintenance costs, in particular for labor.
> Although at 60% of the installed sewage treatment capacity in 
> Holland sludge digestion is applied, it is not very popular compared 
> to aerobic sludge stabilisation, needed for bio-P and bio-N removal 
> in the waterline. 
> 
> Since renewable energy production also is a grow market in 
> Holland, I want to start a discussion on the latest developments in 
> the technical/technological aspects of sludge digestion. Main 
> issues for my part are the increase of gasproduction, reduction of 
> mixing energy, optimal heating of the digesters and easy removal 
> of floating layers. Please feel free to add new issues.
> 
> Please also reply directly to my email-adress below, so I can make 
> a list of contributors to this discussion !
> 
> Ton Schomaker
> 
> +------- HASKONING  Consulting Engineers and Architects -------+
> |                                                              |
> |  AHHM Schomaker                     E-mail: ts@HASKONING.nl  |
> |                                                              |
> |  Barbarossastraat 35             Telephone: +31 24 3284284   |
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+------- HASKONING  Consulting Engineers and Architects -------+
|                                                              |
|  AHHM Schomaker                     E-mail: ts@HASKONING.nl  |
|                                                              |
|  Barbarossastraat 35             Telephone: +31 24 3284284   |
|  6522DK  NIJMEGEN                  Telefax: +31 24 3604737   |
|  The Netherlands                                             |
|                                                              |
+--------------------------------------------------------------+

DIGESTION List Sponsors, Archive and Information
http://www.crest.org/renewables/digestion-list-archive
http://www.crest.org/renewables/biomass-info/
Beginners Tour of Biogas
http://WWW.roseworthy.adelaide.edu.au/~pharris/biogas/beginners