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Doe, David, Dr. Karve,<br>
<br>
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<div class="moz-cite-prefix">On 11/16/2013 6:22 PM, Joe Crescenzi
wrote:<br>
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<div dir="ltr">Centrifugal pump works fine for us here on a 1000
M³ digester. Maintain the pump below the level of the holding
tank to minimize air entry. We do incorporate about 35% liquid
digestate from the digester into the new incoming slurry -
before the pump. <br>
<br>
<div>
<hr id="stopSpelling">From: <a class="moz-txt-link-abbreviated" href="mailto:adkarve@gmail.com">adkarve@gmail.com</a><br>
<br>
<div>Dear Dr. Fulford,</div>
<div>thanks a lot for the explanation and the solution.</div>
<div>Yours</div>
<div>A.D.Karve<br>
<br>
</div>
<div class="ecxgmail_quote">On Sun, Nov 17, 2013 at 12:45 AM,
David <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:davidf@kingdombio.com" target="_blank">davidf@kingdombio.com</a>></span>
wrote:<br>
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0px 0.8ex;PADDING-LEFT:1ex;" class="ecxgmail_quote">
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<div>Dr Karve and listers, Hello,</div>
<div> </div>
<div>Tests I tried in a laboratory which involved
pumping material into a digester suggested that flow
velocity is important.
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<br>
<br>
I have a hard time imagining that the type of pump used would have
any impact on the situation. Logic would tend to make me skeptical.
Consider that some (not all) studies of agitation have shown that
violent or continuous agitation is not beneficial, but for any
microbes passing through a pump, that is a momentary and probably
minor discomfort at worst. Indeed, even if a pump or some other
process is completely <i>sterilizing</i> the incoming slurry--
killing everything, as is occasionally done with garbage or another
biohazard substrate-- then regardless, if what is being fed is
digestible, it will all be colonized and mostly digested during the
period of any sensible HRT. Further, surely if centrifugal pumps,
which have been used for years on digesters, had some negative
effect on digestion, then this would have been noticed and exampled
in the literature. I don't know of any such references, whereas if
the effect were as dramatic as these reports suggest, I would think
this would be a widely known caveat.<br>
<br>
Thus whatever the situation is with the three digesters mentioned by
Dr. Karve, I tend to doubt that it has anything to do with the pump,
regardless that this is a shared characteristic. They may, after
all, each have entirely different causes for their problems. <br>
<br>
Of course, at best that's merely exclusionary, ruling out one
candidate for cause, and it does not solve Dr. Karve's mystery, nor
does it address the experience of Dr. Fulford.<br>
<br>
<br>
d.<br>
<div class="moz-signature">-- <br>
<div style="font:Georgia" ;=""><span style="font-size:110%;">David
William House<br>
</span>
<div style="padding-left:3em;font-size:80%;">"The Complete
Biogas Handbook" <code><a href="www.completebiogas.com">www.completebiogas.com</a></code><br>
<em>Vahid Biogas</em>, an alternative energy consultancy <code><a
href="www.vahidbiogas.com">www.vahidbiogas.com</a><br>
<br>
</code></div>
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<div style="padding-left:2em;">"Make no search for water.
But find thirst,<br>
And water from the very ground will burst."
<div style="padding-left:2em;font-size:80%;">(Rumi, a
Persian mystic poet, quoted in <em>Delight of Hearts</em>,
p. 77) <br>
<br>
<a class="moz-txt-link-freetext" href="http://bahai.us/">http://bahai.us/</a></div>
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