[Digestion] Fwd: providing oxygen to methanogens

[David]

Listers, Hello,

Many years ago, we started a biogas plant fed with cattle dung and liked 
with a pressure gauge. The gas pressure in the plant initially 
decreased, which suggested the microbes were consuming oxygen from the 
air before they produced biogas. The addition of amounts of glycerol and 
vegetable oils are supposed to increase overall gas production, and can 
be regarded as oxygen providers. Excess amounts of these chemicals tend 
to inhibit the process, which links to the idea that oxygen is used, but 
too much is bad.

The chemicals that Dr Karve suggest are used as disinfectants, as excess 
oxygen kills some bacteria. The amount of oxygen that is provided is 
probably important. Small amounts help digestion, larger amounts stop 
the process working. More research seems to be needed.

Best wishes,
David Fulford

------ Original Message ------
From: "Dr Stephen P Etheridge" <spe at biotrix.asia>
To: "'For Discussion of Anaerobic Digestion'" 
<digestion at lists.bioenergylists.org>
Cc: "'Priyadarshini Karve'" <priyadarshini.karve at gmail.com>
Sent: 24/09/2014 11:27:11
Subject: Re: [Digestion] Fwd: providing oxygen to methanogens

>Dear List
>
>Many years ago we found some unexplained stimulation of biogas 
>production
>when oxygen had accidentally been introduced into an anaerobic system. 
>This
>was as air, and not oxygen in chemical form. While this should have
>traditionally been inhibitory to the methanogens, for some reason, in 
>the
>specific circumstances prevailing at the time it was not. At the time 
>we
>explored this in the literature and found a paper by Pirt and Lee which
>indicated recorded stimulation due to oxygen introduction. If I can 
>track it
>down I will forward it.
>
>Regards
>
>Stephen Etheridge
>CEO Biotrix Asia
>
>-----Original Message-----
>From: Digestion [mailto:digestion-bounces at lists.bioenergylists.org] On
>Behalf Of Anand Karve
>Sent: 24 September 2014 17:12
>To: digestion at lists.bioenergylists.org
>Cc: Priyadarshini Karve
>Subject: [Digestion] Fwd: providing oxygen to methanogens
>
>Dear List,
>
>Although the microbes responsible for making biogas work under 
>anaerobic
>conditions, they do use oxygen, which they extract from the feedstock. 
>Thus,
>when you feed them with a carbohydrate, they give back to you methane, 
>a
>hydrocarbon, using the oxygen from the carbohydrate for driving their 
>own
>metabolism. The rate of biogas production is much higher when you use a
>cabohydrate rich substrate rather than dung. In fact the biogas 
>producing
>organisms even convert carbon dioxide into methane. This gave me the 
>idea of
>providing a biogas plant with a chemical rich in oxygen and to see if 
>the
>biogas production is accelerated. Some of the substances classically 
>used as
>oxygen donors in various chemical reactions are potassium permanganate,
>potassium dichromate, potassium chlorate or many of the peroxides, 
>nitrates
>and sulphates. Does anyone have ideas or comments on this theme?
>Yours
>A.D.Karve
>
>--
>***
>Dr. A.D. Karve
>Trustee & Founder President, Appropriate Rural Technology Institute 
>(ARTI)
>
>
>
>--
>***
>Dr. A.D. Karve
>Trustee & Founder President, Appropriate Rural Technology Institute 
>(ARTI)
>
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>for more information about digestion, see
>Beginner's Guide to Biogas
>http://www.adelaide.edu.au/biogas/
>and the Biogas Wiki http://biogas.wikispaces.com/
>
>
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>for more information about digestion, see
>Beginner's Guide to Biogas
>http://www.adelaide.edu.au/biogas/
>and the Biogas Wiki http://biogas.wikispaces.com/
>