[Digestion] Biogas from sewage plants

[Jim and Amy Rankin]

Jorge,

I may be wrong, but I believe the primary problem with anaerobic digestion 
of city sewerage is the dilute feedstock which leads to large capital costs 
to construct large digesters with relatively low gas output/volume due to 
the feedstock being largely water.  So where anaerobic digestion is used, a 
smaller, cheaper digester handles the settled solids and aerobic processes 
are used for the rest.

This model has been in existance for many many years, so there should be 
some good  data out there on what yields can be achieved.  One plant that I 
toured was using the biogas from the sludge to run engines that pumped the 
air for the aeration system of the rest of the plant.  This avoided the 
inefficiencies of electrical generation and utilization since the aeration 
was a constant energy requirement of the plant as a whole.

I do think that anaerobic treatment has not gotten the consideration it 
perhaps deserves in the waste water treatment industry which generally seems 
to think aerobic first and then when that fails due to a high strength 
waste, then finally considers anaerobic.

Jim


----- Original Message ----- 
From: "Montero Arguedas Jorge Mario" <JMonteroA at ice.go.cr>
To: <digestion at listserv.repp.org>
Sent: Wednesday, September 12, 2007 8:54 AM
Subject: [Digestion] Biogas from sewage plants


>I ve tried convincing our municipal plant engineers of this.  What could
> be better than taking care of having the plants electricity bill taken
> care of by the plant itself.
>
> They say it impossible.  That the only viable feasible biogas production
> way would be a UASB (or similar) to digest the sludge from the aerobic
> treatment tanks.
>
> Any comments,  further ideas on this ?
>
>  Montero PE, MS
>
> Instituto Costarricense de Electricidad
> Costa Rica
>
> -----Mensaje original-----
> De: digestion-bounces at listserv.repp.org
> [mailto:digestion-bounces at listserv.repp.org] En nombre de Katahdin
> Energy Works
> Enviado el: Wednesday, September 12, 2007 4:07 AM
> Para: g_vishwas at vsnl.com; digestion at listserv.repp.org
> Asunto: Re: [Digestion] Digestion Digest, Vol 15, Issue 16
>
> One wonders what the cost to enhance/upgrade our local sewerage
> treatment
> plants into bio-gas production facilities would be...it is worthy of a
> national program..what about the distribution network for the gas....or
> should electric production be integrated into sewerage treatment plants?
>
>
> Surely some energy wonk 'out there' must be doing a paper on these costs
> vies a vi the cost of corn to methanol, for example. ..... are sewerage
> treatment plants an unexploited energy reserve?
>
> Frank J. Heller, MPA
> KATAHDIN ENERGY WORKS
> 12 Belmont St.
> Brunswick, ME 04011-3004
> 207.729.6090
> http://mysite.verizon.net/fjheller/
>
> -----Original Message-----
> From: digestion-bounces at listserv.repp.org
> [mailto:digestion-bounces at listserv.repp.org] On Behalf Of Vishwas
> Gokhale
> Sent: Wednesday, September 12, 2007 4:47 AM
> To: digestion at listserv.repp.org
> Subject: Re: [Digestion] Digestion Digest, Vol 15, Issue 16
> http://info.bioenergylists.org
>
>
>
> _______________________________________________
> Digestion mailing list
> Digestion at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/digestion_listserv.repp.org
> Beginner's Guide to Biogas
> http://www.adelaide.edu.au/biogas/
> http://info.bioenergylists.org
>
> _______________________________________________
> Digestion mailing list
> Digestion at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/digestion_listserv.repp.org
> Beginner's Guide to Biogas
> http://www.adelaide.edu.au/biogas/
> http://info.bioenergylists.org
>