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<div class="moz-cite-prefix">G'day Kyle et al,<br>
<br>
My antibiotic experience is at a piggery where weaners were
injected with Ivomec as part of the weaning procedure but the
digester carried on, apparently quite happily. Then one day the
whole herd was fed Ivomec in the feed mix (and of course some feed
spills straight into the drains), which resulted in no gas - the
good part is a few days after stopping pumping into the digester
gas production restarted spontaneously. I doubt if a few cows
would have a bad effect, that said I used cow manure where I found
out the cows were fed antibiotics in another digester and got no
gas for a few weeks, but when I returned from holidays a few weeks
later gas production had commenced.<br>
<br>
Are you talking dairy cattle or beef cattle and what is your
operating temperature? You can use the attached model to try the
variables.<br>
<br>
Happy digesting,<br>
HOOROO<br>
<pre class="moz-signature" cols="72">Mr Paul Harris BEng (Ag) (Melbourne)
Visitor at The University of Adelaide</pre>
On 13/11/2012 6:14 PM, Takamoto wrote:<br>
</div>
<blockquote
cite="mid:B1C98E63-C3B8-401D-97AD-71CFB78F3607@takamotobiogas.com"
type="cite">
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Dear Biogas List,
<div><br>
</div>
<div>I have been testing a plastic (LLDPE) floating drum digester
with cow dung and found that the biogas production was lower
than expected (pH 7, 19˚C) at around 0.5 cubic meters of biogas
per day at 67% methane. The reactor volume is 3.2 cubic meters.
I discovered that our dung supplier had recently used the
antibiotic Tetracycline for a few of his cows so there is a
chance of contamination, though at this point, I feel like the
antibiotic concentration would be very low and should not affect
gas production. Does anyone have experience with the effect of
antibiotics? Also, what gas production should I expect from a
3.2 cubic meter reactor that I add 40 kg of cow dung to per day
(plus 40 kg of water)? If I assume 15% TS and 80% of TS are VS
then the Organic Loading Rate is around 1.5 kg -VS/m3/day and
our specific methane yield is 0.07 m3 CH4/kg-VS and our digester
efficiency is 0.1 m3 CH4/m3 reactor/day. Does this sound
reasonable?</div>
<div><br>
</div>
<div>I have also been reviewing research articles on gas
production from cow dung but the results vary widely and
sometimes I am not sure if the reported results are accurate.
Also, research papers often use CSTR (continuously stirred tank
reactors?) at 37˚C which makes comparing their results to my
results rather difficult. We are getting a new load of
non-contaminated cow dung today to see if that makes a
difference. I'll let you know.</div>
<div><br>
</div>
<div>I am sure this topic has been discussed before, so I am sorry
if I have repeated the topic. I am newish to the forum so I
haven't seen anything on this yet.</div>
<div><br>
</div>
<div>Thanks for your advice,</div>
<div><br>
<div apple-content-edited="true">
<span class="Apple-style-span" style="border-collapse:
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0px; font-size: medium; ">
<div style="word-wrap: break-word; -webkit-nbsp-mode:
space; -webkit-line-break: after-white-space; ">Kyle<br>
Managing Director<br>
Schutter Energy Ltd.</div>
<div style="word-wrap: break-word; -webkit-nbsp-mode:
space; -webkit-line-break: after-white-space; "><a
moz-do-not-send="true"
href="http://www.takamotobiogas.com">www.takamotobiogas.com</a><br>
<br>
<br>
</div>
</span></span>
</div>
<br>
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<br>
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<pre wrap="">_______________________________________________
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