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<font face="Georgia"><br>
Dear all,<br>
<br>
With regard to the post by Alexander quoting two arguments against
biogas, as regards the first problem mentioned-- that conversion
of organic matter by AD might reduce humus-- I can't see the sense
of such an idea. After all, as we all know, biogas plants will not
do well with converting recalcitrant materials into biogas, for a
number of reasons. And if by the word "humus" we are addressing
organic material with any appreciable residence time in the soil--
then such humus is not made from the easily digested or easily
composted fractions of any material. After all, these fractions
are easily converted into simpler chemical species in either a
compost pile or the soil, as well as in a digester. Rather, humus
as defined must be made primarily from the more recalcitrant
fractions-- exactly what is left as effluent.<br>
<br>
If someone can show a well-done study that demonstrates a
significant reduction in humus in otherwise comparable lands
comparably treated, then perhaps it should be a matter of concern,
but the mere statement of opinion, to me, is unconvincing. (As
well, speaking from a more agricultural perspective, it should be
obvious that most humus is grown in, and not added to, the soil.
It consists of decomposing roots, for the most part. In natural
forest or grassland soils with good humus content, who is it that
is plowing in the compost to make the humus?)<br>
<br>
As far as Clostridium, the biogas process does not <i>produce</i>
it; it simply may fail to completely <i>remove</i> it, especially
in shorter HRT mesophilic digesters. One may as well blame the
plastic bottle for the effect of the pesticide it holds.<br>
<br>
If someone puts unsafe materials into a digester, and then </font><font
face="Georgia">is foolish enough to </font><font face="Georgia">put
the effluent on land used for ag uses (whether to produce human or
animal foods), then it should be no surprise if that effluent has
bad consequences. How is it that biogas is to blame where people
have made foolish or ignorant choices?<br>
<br>
<br>
<br>
d.</font><br>
<div class="moz-signature">-- <br>
<div style="" ;=""><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>
<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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