Aquaponics Digest - Sat 12/13/97
Message 1: Biogas generators
from GCR
Message 2: Re: Re: Economics/Sustainability of production
from FranksFarm
Message 3: Re: Re: Re: economics/sustainability of production
from YankeePerm
Message 4: Re: Re: Economics/Sustainability of production
from YankeePerm
Message 5: Re: Plant crop questions.
from "Harrop"
Message 6: Re: Biogas generators
from YankeePerm
Message 7: Re: Pathogens and A/D
from "Harrop"
Message 8: Re: Plant Crop Questions
from Rebecca Nelson
Message 9: Re: Re: Re: economics/sustainability of production
from "H.Doelle"
Message 10: Re: Pathogens and A/D
from "H.Doelle"
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 1 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Biogas generators
From: GCR
Date: Sat, 13 Dec 1997 07:54:19 +0000
I have a friend who would like to build a water hyacinth fueled biogas
generator in the Pantanal swamp in Brazil to provide electricity for the
Indians living there. Can someone direct me to information on the net or
individuals that can help him?
Is it even feasible?
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 2 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Re: Economics/Sustainability of production
From: FranksFarm
Date: Sat, 13 Dec 1997 10:01:47 EST
Hi,
just wanted to say that I too agree with much of what Jack Rowe said in his
post about sustainable/more efficient holistic systems.
But that view raises so many questions.
First Jack repeated that in Asia ponds are often fertilized with manures that
are rich in nutrients utilized by plankton ( low level on food chain).
Lloyd and others have pointed out that bacteria etc in manures can cause
influenzas, viruses etc. if pathagens in manure are not destroyed. Seems
reasonable to me.
My question is how do we figure out how much manure /nutrients the plankton
can handle or process safely , and in what period of time.
It also seems to me that many animals do not eat their own wastes unless
specially adapted to such...which to me indicates that we should probably not
be feeding animal wastes directly to animals, but rather through organisms
designed to break them down.
I've also heard a lot of talk about growing blue algae( spirulina?) for food
etc. Are there any commercial fish that can be raised off such a diet mainly
of such algae? Or could smaller fish be raised off it that in turn are the
main diet for larger commercial fish?
Has anyone tried it?
Please remember that my comments are based not upon first hand experience, but
rather on lots of reading, and listening.
To me balance is always the answer, but it is difficult to achieve....and hard
to know. It also seems in nature that the more complex the system the easier
it is to maintain... quite a paradox!
Appreciate comments from the list on this. Perhaps by utilizing our combined
talents we can come close to developing such a sustainable system that can be
successfully replicated in an efficient yet profitable manner.
Happy Holidays to all. frank
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 3 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Re: Re: economics/sustainability of production
From: YankeePerm
Date: Sat, 13 Dec 1997 13:46:42 EST
Several points I made were apparently not clear:
In a message dated 12/12/97 5:45:25 PM, H.Doelle@mailbox.uq.edu.au wrote:
>Of course, you have to have a certain C/N ratio, which is always present in
human
>or animal waste.
>
* RESPONSE; My point was that in gathering supplemental (plant) materials to
animal wastes, including human, attention should be given to the proper C/N
ratio. Actually, animal manures, including human which can be equated with
pig manure in most respects, are too rich in N and supplemental C is advisable
to optimize methane yield. This is done by adding plant materials, generally
crop residues. Straw and other light materials are to be avoided as they form
a crust which inhibits release of methane. Therefore, CH4 builds up in the
slurry. The increase of dissolved waste (CH4) inhibits the methanogenic
bacteria from producing more, as of course their wastes are toxic to them in
sufficient concentrations. This is basic methane digestor info--I'm not sure
how useful it is in the aquaculture list, but certainly if included it should
be accurate.
>The Chinese have mainly small digesters feeding small nuclear families. A
family
>of four can easily get enough biogas from 2-3 cows plus their own family to
boil
>even more than a couple of eggs for breakfast.
>
>
RESPONSE; The chinese also have larger digesters that they use in the cities,
principally in the North. In this case, a building full of people can be
equated to a barn full of pigs, for methanogenic purposes, except that people
produce far less excrement per capita. My statement was that a nuclear family
could not produce enough methane to boil an egg. This is correct. I have
done the numbers. If they have as many cows as people, they probably have two
orders more manure than if there just people. There is no way that China
could feed that many cows, of course. In much of asia, methane digesters are
used in community toilet facilities. I think it might be dangerous to
generalize anything about China as one could not live long enough to visit the
diverse conditions in that country.
>I always emphasized that energy production depends on the region and
availability
>of resources. Biogas is not only for tropical rural countries. We also have
sewerage
>plants in our developed country cities and can use the biogas.
>
>
RESPONSE; Yes, here the numbers of human contributors are useful. I have
proposed this also for schools in semi-rural areas where a methane digester
would produce fuel and eliminate need for an expensive and dependence-inducing
hookup to a local sewage treatment plant. Most municipal sewage systems in
the US take off some methane but do not usually optimize treatment for methane
production. Suprious dumping of toxic chemicals is problematic as they kill
the bacteria that generate CH4 and therefore ruin treatment efforts. These
toxics are difficult to trace back to the source in urban areas. Some 30 or
so years ago I designed a system for handling this problem, but again it seems
a bit far afield from aquaculture.
>Anaerobic digestion of manure is the only way of killing pathogens and not
risking
>diseases. Manure can not be properly *composted* to free it from disease
causing
>microbes. The effluent or solids from an anaerobic digester can safely be
used
>for composting.
>
>
RESPONSE: This is erroneous. Methane digesters do not kill all pathogens and
they operate at conditions natural to some (anerobic conditions at body
temperature). Generally, digesters kill enough of the pathogens that there
are fewer, proportionally, than in the soil to which the slurry is applied so,
nonetheless the pathogens in the soil are diluted. (Work in Korea and India
have independently demonstrated this effect.) Hot composting subjects the
pathogens to completely different conditions, including much higher than body
temperatures and aerobic conditions. The organisms involved are different so
they are likely to "eat" those pathogens missed by the anerobic process. It
is therefore prudent to follow anerobic digestion with hot comoposting where
intestinal diseases and parasites are rampant. However, if these are abundant
in the soil, there is no point in being overly fastidious in the manure
processing until the soil population has been reduced. There are techniques
for hastening this, but in mainly depends on getting people to crap in the
outhouse instead of the field. This is harder than you may think.
>If you do not believe this, make a test for E.coli and you will find out very
easily
>yourself.
>
>Cheers
>
>Horst Doelle
RESPONSE; All human digestive systems contain E coli. Indeed they are
responsible for producing some important B-complex vitamins in the human
intestine. Where people have been raised in an overly sterile environment,
they may be susceptible to some of the many strains of E coli. However in
general this is a symbiote of humans and used as an indicator human (and other
animal) wastes because it is ubiquitous. Each microorganism has its own
tolerances to digestion conditions. Those adapted to the human intestine are
likely to find a methane digester hospitable, except that they are subject to
attack by other microorganisms. A methane digester is basically an artificial
intestine run a body temperature (or a bit higher--there are two optimum
temperatures) to produce farts (methane). These farts are produced in
identical ways whether the intestine is organic or synthetic. Obviously there
are (different) microorganisms that survive all forms of composting, because
the compost process is driven by them. The more one varies the environment
before releasing the material back to soil, the more organisms are killed.
In general, the percent of demise of resident pathogens in manures depends on
oxygen conditions, temperature and time. This is well treated by Joe Jenkins
in an excellent section on pathogens in THE HUMANURE BOOK. Email me privately
to find out more about that book.
For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since 1982),
Elfin Permaculture workshops, lectures, Permaculture Design Courses,
consulting and permaculture designs (since 1981), and now correspondence
courses via email. One is now underway. Next Live program: Paraguay,
8/10-22/98. Internships available. Copyright, 1997, Dan & Cynthia Hemenway,
P.O. Box 52, Sparr FL 32192 USA YankeePerm
We don't have time to rush.
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 4 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Re: Economics/Sustainability of production
From: YankeePerm
Date: Sat, 13 Dec 1997 14:22:03 EST
Hi Jack:
Nice post, though it has simplifications which I will address privately. I
think that you have taken the aquaculture group about as far as they are able
to go.
Dan
In a message dated 12/13/97 1:14:10 AM, you wrote:
>I suspect, without knowing many specifics, that your point raises a valid
>
>health concern, Lloyd. In fact, influenza might be only one of the
>
>possibilities arising from careless handling of fish raised in direct
>
>contact with human and animal manures. E. coli, cholera, salmonella, etc.
>
>come to mind... thorough cooking would be a necessity in these situations,
>
>as it is with chicken 'manufactured' in the US.
>
>
>
REPLY; Probably this is why the Chinese thoroughly cook everything, including
fish. Sushi is from wild, oceanic species, to my knowledge.
>One of my two major points was the desirability of careful use/reuse of all
>
>'waste' products -- which can be seen as either resources or pollution.
>
>When we treat manure as pollution, we pay to have it 'removed' (to where?).
>
>Wastes treated as pollution tend to accumulate and, in fact, begin to act
>
>as pollutants. When we call a waste a resource, we are often able to find
>
>productive uses. The material may be the same in either case, but our
>
>perception by itself can change that material from a liability to a
>
>valuable resource -- or vice versa.
>
>
>
>The other point is that, each time we move a step up the trophic/food
>
>ladder, a great deal of energy is used. Food-to-meat conversion factors
>
>tend to be 20% at the best and are usually much lower (fish are very
>
>efficeint at food conversion, happily). We will always get the biggest
>
>'bang for our buck' if we feed at the lowest point on the trophic ladder
>
>that we can.
RESPONSE; Hopefully you understand that this is an oversimplification. My
chickens, for example, eat at every level of the tropic ladder they find.
They are therefore efficient because nature doesn't confine herself to the
lowest "level" (I dislike the hierachical metaphor for food webs, but I'll put
up with it temporarily). Not only is there grass, weeds, young leaves and
stems of woody plants, Spanish moss, etc . which my chickens eat at the
"bottom" of the food chain, there are also slugs (not many in sandy Florida),
grasshoppers, crickets, palmeto bugs (giant roaches), frogs, lizards, magots,
grubs, well insect larvae of all types, etc. I've seen chickens eat stuff
that would gag a buzzzard. They also eat below the "lowest level," not only
ingesting portions of their own shit, but quite a quantity of compost. While
there is a lot of energy expended in beating entropy back all the way to, say,
produce a cricket frog, some of it is like potential energy. So long as the
nutrients are concentrated, the energy is unavailable. When the concentration
is dispersed, say partly in chicken shit, the value of some of that energy is
recovered. Think of it this way--lifting water to the top of a mountain is
concentrating its property of elevation which is dispersed as the water falls,
again creating harvestable energy.
Moreover, how is it not efficient to tap into everything that is available up
to the size of, say, a one foot snake? Only if one adopts the linear
efficiency concept of an engineer that looks only at one value at a time can
one say eating snakes, which are there an;yway, is less efficient than eating
grass, which requires a couple orders of magnitude (I'm guessing) more energy
expenditure per calory or gram of protein assimilated.
>>In general terms, feeding high-protein food to catfish (which
>
>are scavengers), for instance, is for this reason not 'economical' when
>
>viewed in holistic or ecological terms. Intensive feeding in aquaculture or
>
>agriculture raises production dramatically, but it does not necessarily
>
>raise cost-effectiveness of an overall operation due to the law of
>
>diminishing returns (land and materials costs, of course, force production
>
>to reach toward the highest compromise between intensive production and
>
>least input, fueling some degree of energetic inefficiency in return for
>
>financial viability).
>
>
>
>Feeding at the lowest trophic level is why ponds are most-economically
>
>fertilized with calcium and phosphorous... these are critical elements in
>
>the production of phytoplanktons and zooplanktons, which form the base of
>
>the food 'pyramid' in aquatic systems (economically important herbivorous
>
>fish being fairly uncommon
RESPONSE; Only in North America, which has atypical aquatic ecosystems in
this regard. Still, we do have the buffalo fish. Your mention of the carp is
a case in point. And what about detritus eaters such as crawfish--are they,
again, at a "negative" value on the food chain? I sticked catfish in with a
heavy population of indigenous crawfish because my crawfish harvesting
attempts were ineffectual. What is "efficient" for me is that there is a 5
pound cat fish available when I want it instead of just a few half-ounce
crawfish.
>>-- unless we call phytoplankton eaters
>
>herbivores). Manures are rich in phosphorous, and often rich in calcium. A
>
>great deal of production can come from feeding manures to the planktons,
>
>whereas few of the animals higher on the trophic ladder will eat manure to
>
>advantage (a valid fact pointed toward by Lloyd). Manures are ubiquitous
>
>and generally more common than natural sources of high-analysis nutritive
>
>minerals.
>
>
>
>However, manures are an energetic step up from minerals and are also rich
>
>in nitrogen, which is almost never a limiting factor in fish production and
>
>is often a harmful pollutant causing turbidity and lowering of dissolved
>
>oxygen levels. Perhaps manures are best 'composting' during biogas
>
>(methane) production and then used as fertilizers in terrestrial
>
>applications. Conventional sewage treatment produces biogas... the
>
>difference is that the methane is seen as pollution an is not captured for
>
>use (an electrical generation plant in Stanton, CA uses human sewage to
>
>produce the gas which fires its generators).
RESPONSE; This is an error. Most treatment plants capture enough methane to
burn to maintain the proper digester (treatment) temperature. A number,
though still a small percentage, also now use methane-burning vehicles instead
of just releasing or burning off the "surplus." However I doubt that there is
a sewage plant design engineer in North America that has seriously considered
designing a plant to optimize methane digestion, even though this would
inherently lower BOD of the discharge effluent.
>>Manures can in fact be
>
>safely-recylced in a number of ways which use their nutritive value to
>
>postive effect instead of purposely dissipating it at considerable expense.
>
>
>
>
>
>Producing our needs at the lowest economic, energetic and ecological costs
>
>is the critical next step in aquacultural and agricultural systems (as in
>
>other systems). We'll continue to learn more efficient ways of, as Paula
>
>put it, "...raising fish and plants in a synergistic system... to produce
>
>products we could consume and sell as "safe", while using a more natural
>
>method of fertilization...". In the process, we'll have to explore many
>
>ideas and look at our energy and materials cycles in a new light.
>
>Eventually we will come up with ways to produce our needs without relying
>
>on fossil fuels to power the necessary cycles, and without creating
>
>pollution from materials which could be used productively instead. As one
>
>definition of sustainability puts it, "Sustainability is meeting our needs
>
>without endangering the ability of future generations to meet THEIR needs".
>
>A worthy goal we're all in agreement with.
>
>
>
>Jack Rowe
RESPONSE; Nice nudge in the right direction. AND, we both know that any
concentrated food production has as its greatest energy cost the transport of
the food to where it is eaten, second greatest being processing/cooking. So
we are back, if we seek sustainability, to encouraging decentralized systems.
As an aside, this is a problem I have with CSAs. In general, it seems that
people are tooling around in their cars, back and forth from the CSA farm,
adding such a horrendous energy cost to the food that we would better buy it
from the supermarket by a large measure as far as sustainability is concerned.
For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since 1982),
Elfin Permaculture workshops, lectures, Permaculture Design Courses,
consulting and permaculture designs (since 1981), and now correspondence
courses via email. One is now underway. Next Live program: Paraguay,
8/10-22/98. Internships available. Copyright, 1997, Dan & Cynthia Hemenway,
P.O. Box 52, Sparr FL 32192 USA YankeePerm
We don't have time to rush.
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 5 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Plant crop questions.
From: "Harrop"
Date: Sat, 13 Dec 1997 15:08:58 -0500
Basil is a good bet; lettuce only if you have REALLY unique varieties or
are providing for farmer's markets. Try FRESH catnip....believe me, it
sells. ROB
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 6 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Biogas generators
From: YankeePerm
Date: Sat, 13 Dec 1997 15:20:40 EST
In a message dated 12/13/97 12:46:42 PM, you wrote:
>I have a friend who would like to build a water hyacinth fueled biogas
>generator in the Pantanal swamp in Brazil to provide electricity for the
>Indians living there. Can someone direct me to information on the net or
>individuals that can help him?
>
>Is it even feasible?
This has been tried though I don't know how successfully. I do recall reading
of a WH system in which the plants were part of a biological sewage treatment
system and then were harvested and digested along with sewage. They were
particularly effective at concentrating heavy metals and periodically the WH
was burned to harvest the metals in the ash.
I hear reports of WH digesters in various areas but no yield data. The
problems are 1) the plants are mainly water so the concentration of digestible
material is low. This requires the digester to be very, very close to the
plants to be potentially practical. 2) Much of the dry matter is a very tough
fiber that might cause problems for the digester. Batch processing with a
number of moldular digesters could be the solution, With periodic clearning of
resistant material. The working digesters can be arranged so that one is the
primary unit and others are for tailing, getting the last fraction of methane
before the slurry goes back to the hyacinth pond. By adding domestic and
livestock wastes, the fertility of the waters can be built up. Surplus slurry
can be bled off for various jobs. This should be very, very low in pathogens.
Water hyacinth as feedstock for digesters was treated in one, or maybe two, of
the development books published by the US Academy of Sciences (B.O.S.T.I.D.
publications). One was on using water weeds and the other was on methane
digesters. Unfortunately, we are in flux here and my books are waiting to be
moved to a new library room so I cannot give precise info. Email me privately
if you want a BOSTID address. We publish a database of 2,000+ such useful
addresses and I'll look it up for you offline.
For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since 1982),
Elfin Permaculture workshops, lectures, Permaculture Design Courses,
consulting and permaculture designs (since 1981), and now correspondence
courses via email. One is now underway. Next Live program: Paraguay,
8/10-22/98. Internships available. Copyright, 1997, Dan & Cynthia Hemenway,
P.O. Box 52, Sparr FL 32192 USA YankeePerm
We don't have time to rush.
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 7 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Pathogens and A/D
From: "Harrop"
Date: Sat, 13 Dec 1997 15:20:44 -0500
Dear Horst:
First, let me declare that I an not a microbiologist; however, what
assurances do we have that all pathogens are "neutralized" during the
digestion process? Are pathogens killed by heat or other factors in the
process? I've audited a first-year microbiology course at a university and
the lab results freaked me out (swabs taken from public telephones, etc.);
I almost turned into a hypochondriac ( joking).
The pontential benefits from A/D (anaerobic digestion) intrigue me both
from an energy source potential as well as providing fish protein. By the
way, GREAT group and thanks to the folks at S&S Farms for taking the
initiative to develop this valuable resource. Rob
----------
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 8 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Plant Crop Questions
From: Rebecca Nelson
Date: Sat, 13 Dec 1997 14:09:03 -0800
Paul V. Wojcik wrote:
> I'm setting up a small 14'x20' NFT hydroponic greenhouse for year-round
>
> I was wondering...
>
> What is the best market in your area, farmers markets, grocery stores,
> restaurants, or somewhere else?
We have 7,000 sq ft in controlled environment hydroponic production.
The primary crop is tomatoes, but we also grow hydroponic cukes, basil
and beans commercially. We market all of our produce directly to
non-chain grocery stores. We've found the large chains in our area
(Central California) to be difficult to get into unless you can supply
all of the stores within the chain.
> Are your herbs dry or fresh?
> How do you package your vegetables & herbs?
We sell the basil fresh because there is a demand for it and the
wholesale price is quite high. We take cutings from each plant weekly,
tie them in a bunch and package the bunches in clear plastic containers
that have a little well in the bottom that we put a moist plant cube in
for the stem to stick into. This keeps the basil alive and even
growing. The stores and customers love the presentation and the fact
that the fresh basil keeps for over a week in this container.
We hand-pack the tomatoes in colorful, singe layer, 10-lb tomato boxes.
We place a label on each tomato that tells the customers that it is vine
ripened, hand picked and hydroponically grown. The label also has our
trademarked product name (Grandpa's Garden) on it.
>
> Where do you get thin plastic clamshell boxes and other packaging for
> herbs?
The container I described above is availables from CropKing
330-769-2002. A company that has an extensive catalog of containers
for fresh produce is Monte Packaging 800-653-2807
> What price do you get for your various herbs?
We wholesale the basil ( 1.5-2.0 oz) in the containers for $1.00 -
$1.25/each
> If you grow basil, what varieties do you grow?
Italian Large Leaf
Purple Ruffles
> Are there any value-added products that you make with your herbs or
> vegetables?
We plan to add a seasoning mix of dried tomatoes and basil. It is a
great way to use the tomato seconds
Rebecca Nelson
Aquaponics Journal
209-742-6869
http://www.aquaponics.com
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 9 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Re: Re: economics/sustainability of production
From: "H.Doelle"
Date: Sun, 14 Dec 1997 09:46:08 +1100
Many thanks for your microbiology lecture. Of course, as a microbiologist
myself all these things are known to me, although I do not agree with all
points you raised.
I refrained under the topic aquaponics to give a detailed micro lecture.
I mentioned before I visited near Shanghai digester complexes around 2000
m3. The facts are, and you can go to Manila [Maya Farm], where a family of 4
can produce enough biogas for their cooking, whatever your calculations are.
They are especially trialling digester sizes for this.
Furthermore I simply want to warn aquaculturists of the use of manure
straight for fish feeding or any farm fertilisation. I have seen the systems
and the consequence. I have seen totally contaminated pickeled cucumbers due
to the use of manure fertilisation and I can give you many examples.
In regard to compost, most composting areas I have seen take shortcuts and
thus your theory, although correct in principle, never works in practice.
People always forget that large family numbers very often are the result of
low health standards. We have to improve health standards to cut down family
size and give all people the right to live. There are no shortcuts to do
that. Prevention is better than combating disease.
Cheers Horst
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 10 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Pathogens and A/D
From: "H.Doelle"
Date: Sun, 14 Dec 1997 10:08:47 +1100
Dear Rob,
Nothing works 100 per cent. You have no assurance at all that ALL pathogens
are killed during the digestion process or the composting.
That sounds scary, but we have to realise that. However, we can reduce the
number of *dangerous* pathogens very significantly, so there numbers are
less in the food chain than in our gut.
What scarce me is the shortcuts taken under the heading *economy* by people
not realising that MICROBES ARE THE MOST POWERFUL CREATURES IN OUR LIFES.
They can kill but also be beneficial. We created an environment whereby the
former are becoming dominant according to WHO figures and we have to get the
balance back.
Pathogens - it sounds amazing - are required for our digestive system, but
in a certain proportion.
In Asia and many other developing countries one cannot drink water. WHY ?
Because we do not teach them to do what we are doing, build sewerage plants,
which are nothing more than anaerobic digesters plus various other treatments.
Microbiology unfortunately goes all into genetical engineering and molecular
biology, a danger with that is, that we neglect the basic principles.
Therefore we have to be careful in trying to implement systems, which are
not safe.
With the antibiotic resistancy going up, we have to start PREVENTION, since
we are loosing the battle with COMBATING the disease when it occurs.
CAUTION is what I am talking about. Test the facilities for pathogens. There
are plenty of methods available. WHY IS THAT NOT DONE IN AQUACULTURE or
other areas where manure is being used styraight without treatment ?
We are testing everything, except for pathogens. If somebody can give me
proper test figures that the practice is safe, ok. I have not seen a single
one as yet, certainly not in developing countries.
I hope I answered some of your questions
Looking forward to more discussion,
Cheers Horst
At 03:20 PM 13/12/97 -0500, you wrote:
>Dear Horst:
>First, let me declare that I an not a microbiologist; however, what
>assurances do we have that all pathogens are "neutralized" during the
>digestion process? Are pathogens killed by heat or other factors in the
>process? I've audited a first-year microbiology course at a university and
>the lab results freaked me out (swabs taken from public telephones, etc.);
>I almost turned into a hypochondriac ( joking).
> The pontential benefits from A/D (anaerobic digestion) intrigue me both
>from an energy source potential as well as providing fish protein. By the
>way, GREAT group and thanks to the folks at S&S Farms for taking the
>initiative to develop this valuable resource. Rob
>----------
>> From: H.Doelle <
>> To: YankeePerm <
>> Cc: S & S Aqua Farm <
>> Subject: Re: Re: economics/sustainability of production
>> Date: Friday, December 12, 1997 5:56 PM
>>
>> Of course, you have to have a certain C/N ratio, which is always present
>in human or animal waste.
>>
>> The Chinese have mainly small digesters feeding small nuclear families. A
>family of four can easily get enough biogas from 2-3 cows plus their own
>family to boil even more than a couple of eggs for breakfast.
>>
>>
>> I always emphasized that energy production depends on the region and
>availability of resources. Biogas is not only for tropical rural countries.
>We also have sewerage plants in our developed country cities and can use
>the biogas.
>>
>>
>> Anaerobic digestion of manure is the only way of killing pathogens and
>not risking diseases. Manure can not be properly *composted* to free it
>from disease causing microbes. The effluent or solids from an anaerobic
>digester can safely be used for composting.
>>
>>
>> If you do not believe this, make a test for E.coli and you will find out
>very easily yourself.
>>
>> Cheers
>>
>> Horst Doelle
>>
>> At 03:22 PM 12/12/97 EST, you wrote:
>>
>> >
>>
>> >In a message dated 12/12/97 2:14:54 PM, H.Doelle@mailbox.uq.edu.au
>wrote:
>>
>> >
>>
>> >>
>>
>> >>The above is only save AFTER anaerobic treatment of the waste. That is
>the
>>
>> >practice
>>
>> >>we introduce now in the Pacific, how it is increasingly used in China .
>We
>>
>> >can
>>
>> >>reduce infectious diseases significantly if we use common sense and
>stop
>>
>> >knocking
>>
>> >>the production of biogas, which actually could provide all the energy
>for
>>
>> >your
>>
>> >>fish farming.
>>
>> >>
>>
>> >>Horst Doelle
>>
>> >
>>
>> >It is my understanding that there are 15 million methane (biogas)
>digesters
>>
>> >operating in China. The Chinese are nothing, if not practical. However
>>
>> >methane digesters only work where there is an adequate concentration of
>manure
>>
>> >and/or other organic material making up a suitable C/N ratio. The
>manure a
>>
>> >nuclear family produces, for example, wouldn't produce enough methane to
>boil
>>
>> >their breakfast eggs. Cattle in confinement, or on a larger scale pigs
>and
>>
>> >poultry, produce adequate amounts, but confinement systems are often
>>
>> >profoundly inappropriate both in terms of resource utilization and in
>terms of
>>
>> >respect for the conditions and enjoyment of life of the animals.
>>
>> >
>>
>> >All this is by way of saying that there are many models. Methane
>digesters
>>
>> >are great in many conditions where feedstock is produced at adequate
>scale.
>>
>> >They are particularly useful in tropical and subtropical areas for
>health
>>
>> >reasons unrelated to aquaculture as one stage in treatment of human
>wastes.
>>
>> >
>>
>> >This brings to mind some claimes I have heard John Todd make about
>raising
>>
>> >striped bass and other fish in seweage treatment waters. I'd like to
>hear
>>
>> >from someone on the list who may be more familiar with what John had in
>mind
>>
>> >than am I.
>>
>> >
>>
>> >For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since
>1982),
>>
>> >Elfin Permaculture workshops, lectures, Permaculture Design Courses,
>>
>> >consulting and permaculture designs (since 1981), and now correspondence
>>
>> >courses via email. One is now underway. Next Live program: Paraguay,
>>
>> >8/10-22/98. Internships available. Copyright, 1997, Dan & Cynthia
>Hemenway,
>>
>> >P.O. Box 52, Sparr FL 32192 USA YankeePerm
>>
>> >
>>
>> >We don't have time to rush.
>>
>> >
>>
>> >
>>
>> Horst W.Doelle,D.Sc.
>>
>> Director, <MIRCEN<-Biotechnology Brisbane
>>
>> Chairman, IOBB
>>
>> Hon.Member of Depts. Microbiology & Chemical Engineering
>>
>> FAX: +617-38783230
>>
>> Email: H.Doelle@mailbox.uq.edu.au
>>
>>
>
>
Horst W.Doelle,D.Sc.
Director, MIRCEN-Biotechnology Brisbane
Chairman, IOBB
Hon.Member of Depts. Microbiology & Chemical Engineering
FAX: +617-38783230
Email: H.Doelle@mailbox.uq.edu.au
|
