[Stoves] Cleaning Dung

[Kevin]

Dear Frank
----- Original Message ----- 
From: "Frank Shields" <frank at compostlab.com>
To: "'Discussion of biomass cooking stoves'" 
<stoves at lists.bioenergylists.org>; "'SARBAGYA TULADHAR'" 
<sarbagya007 at gmail.com>
Sent: Monday, March 19, 2012 1:48 PM
Subject: Re: [Stoves] Cleaning Dung


> Paul, and stovers,
>
> <snip>
>
> 6.  Also, is what is washed from dung better, same, or worse for energy
> content than what is left in the washed dung?  This has probably been
> studied, but I do not know that answer.  Anybody?

# The Dung from Ruminants is the end result of well ground vegetative matter 
being very fully digested.  Basically, the animal's digestive system is able 
to remove about 90% of the cellulose and hemi-cellulose content in the feed, 
leaving behind the "undigestables", which are very high in Lignin. Lignin 
has a significantly higher content calorific value than cellulose and 
hemi-cellulose, so that "washed dung" will inherently have a higher 
calorific value than "dirty dung".

# What is removed from dung in the washing process are:
--> Proteins
--> Micro nutrients
--> Hormonal metabolites
--> Nitrates
--> Chlorides
--> Sodium
--> Potassium
and probably a whole lot more!!

# All the above "wash water constitutents, except when possibly used in 
excess, are excellent Fertilizer additions to marginal soils. Not only does 
the washing prevent destruction of a valuable fertilizer resource, but the 
washed dung makes a superior fuel, for the following reasons:
1: It has a higher calorific value
2: Chlorides interfere with combustion, and removal of chloride content can 
result in improved combustion.
3: Removal of the Chloride from the fuel removes the dioxin hazard 
associated with burning fuels containing chlorides.
(I suspect that a large percentage of IAQ related illnesses in dung burning 
situations are due to the contained chlorides.)

# I have been advocating "Dung Washing" and utilization of the washings for 
"Fertigation" for about 6 years now. I am very pleased to see people 
actually doing it now. I would also encourage greater use of the "Copper 
Wire Test for Halogens", which I suggested at about that time, to detect 
likely dioxin conditions. Hopefully, the Subject is now becoming fashionable 
enough such that sokeone will do a PhD on "The Merits and Consequences of 
Dung Washing."

# Chicken Dung, or manure, or bedding material, should also be washed , for 
the same reasons, if it is to be used for fuel purposes, or biochar 
manufacture (ie, 'Chicken Char.") I suspect that most of the chlorides will 
report to the pyrolysis gas and liquids fraction, where they will form 
dioxins. There could be a great danger to the whole Biochar Industry, if the 
pyrolysis products from a Chicken Char" operation are tested for dioxins, 
and if there is an "Environmental Over-Reaction".

Best wishes,

Kevin

>
>
> [*] From my dung washing experience (along with compost, AD digestate 
> etc.)
> what is real important is how the material is handled. If it is allowed to
> pick up dirt and sand (does so very easily) and if that remains on the
> screen could greatly lower the energy value. Compost typically has 50% ash
> and most of that is dirt and stones. Dung can have much more.
>
> Also the amount loss during washing depends on what the animal eats and 
> its
> digestion system. Cow will mostly get washed out where horse will have a 
> lot
> left for use.
>
> I think handling is most important as to final quality.
>
> Frank
>
>
> Frank Shields
> 42 Hangar Way
> Watsonville,  CA  95076
> (831) 724-5244 tel
> (831) 724-3188 fax
> frank at biomasslabs.com
>
>
>
> .
>
>
>
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