[Digestion] Dung burning vs Anaerobic digestion

Alastair James Ward Alastair.Ward at agrsci.dk
Fri Nov 16 00:21:48 PST 2012

Dear Kassuwi,

I usually find cattle manure has a quite acceptable C:N ratio of about 19, but is still useful to co-digest with a high N substrate such as the fish wastes which are difficult to digest as a mono substrate. I am successfully doing this in partnership with Bioforsk of Norway but there is certainly a risk of inhibition if the mixture is wrong. The addition of fish wastes or similar can drastically increase the volume of biogas produced, but I do not think it has much effect on the degradation of lignocellulosic materials. This problem is better tackled through pre-treatment processes, of which there are many with varying degrees of effect on different substrates. The large amount of information regarding pre-treatment of lignocellulosics is mostly because of the interest in second generation bioethanol rather than biogas, but the treatment processes can often be used for either. On the other hand, pre-treatment usually requires expensive equipment and energy input and so is generally not suitable for the small scale digesters in developing countries which are often discussed on this list.

Med venlig hilsen
Alastair James Ward
Post doc.

Inst. for Ingeniørvidenskab
Aarhus Universitet
Blichers Allé 20, Postboks 50
8830 Tjele

Tlf.: 8715 7645
Mobil: 4112 2494
Email: Alastair.Ward at agrsci.dk

Tlf.: 8715 6000
Web: www.agrsci.au.dk<www.agrsci.dk>

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From: Digestion [mailto:digestion-bounces at lists.bioenergylists.org] On Behalf Of Shaaban Kassuwi
Sent: 16. november 2012 06:14
To: digestion at lists.bioenergylists.org
Subject: Re: [Digestion] Dung burning vs Anaerobic digestion

Dear Members of Digestion group,
The arguments that Cow dung produces low biogas when used in Anaerobic digestion it is the fact which is well known, and the reason has been attributted to high content of Lignin materials which are difficult to be digested by microbes. However, a number of research has been going on to enhance biogas production from cow dung. One of the technique which seems to be promising is the Co-digestion with another substrate with for example high Nitrogen contents, as we know Cow dung is rich in Carbon, so when is digested with eg Fish waste which is rich in N in form of Protein could raise the C:N ratio and improve biogas production. To do this one however needs to establish exact amount of substrate to be co-digested to avoid the problem of Ammonification and Long Chain Fat Acid (LCFA) caused by Protein and Fat Rich substrates. So I would suggest people to start co-digesting and will see improvement to their digestors

Kassuwi, S.A.A
Box 35179

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