Aquaponics Digest - Sun 02/08/98
Message 1: Re: methane digesters
from "H.Doelle"
Message 2: Re: algal nutrition for tilapia
from "Ted Ground"
Message 3: MANURE- BREAK OUT THE HIP WADERS
from "Ted Ground"
Message 4: Re: MANURE- BREAK OUT THE HIP WADERS
from "H.Doelle"
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| Message 1 |
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Subject: Re: methane digesters
From: "H.Doelle"
Date: Sun, 08 Feb 1998 10:15:10 +1100
You are perfectly correct, Jack. It always beats me, why some people can not
comprehend that they virtually could make millions of dollars from waste. If
I would be 30 years younger with my present knowledge, I certainly would
know what to do !
Why are we ignoring the old technologies, which work so much better than
many of the modern ones and are so much cheaper. Has really everything to be
glittery and push-button operated ?
In regard to your ethanol from sugary wastes, thgis depends erally on the
amount of sugar in the waste. Since ethanol is miscible with water, you must
have at least 10-12% sugar in your waste in order to be able to distill
ethanol reasonably economical. The energy costs of distillation are such,
that it becomes only a reality above 7%(v/v) ethanol in the destillate.
Thuis is the reason, why the conversion of molasses into ethanol is such a
borderline case, depending on the sugar content of your molasses.
You are on the right track though, as the future lies in multiple production
with multiple microorganisms from bacteria --> fungi ---> algae, depending
what your needs are.
Cheers
Horst
At 11:14 AM 07/02/98 -0500, you wrote:
>Thanks, Horst,
>
>For the reference on polyethylene methane digesters. Interesting -- I had
>no idea they could be done so cheaply! Apparently, in addition to removing
>methane from wastes (with little or no loss in fertlizing value),
>sugar-rich vegetable wastes can be fermented for alcohol prior to methane
>digestion, again with little or no loss in either fertilizer value or OR
>ability to produce methane (Mollison, Jack's notes).
>
>Jack Rowe
>
>
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
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| Message 2 |
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Subject: Re: algal nutrition for tilapia
From: "Ted Ground"
Date: Sun, 8 Feb 1998 04:12:52 -0600
James,
Wanted to let you know that I generally agree with your analysis of algal
inputs, except to say that in a study of tilapia feeding on both pellets
and natural phytoplankton in Israeli ponds (I am drawing this from memory,
so take this with a grain of salt) carbon isotope analysis of the tilapia
carcasses indicated that 50% of their carbon was from algal and bacterial
detritus consumption and assimilation- which doesn't quite line up with
your 33% on algae alone if I read your posting correctly- but it is close,
and probably within analytical or experimental error ranges and certainly
within the broad ballpark of agreement that we have to expect in any system
in which biology is involved.
My earlier comments on algae, as you recall, did not advocate algae as a do
all and be all- I simply suggested that some supplemental algae could serve
as a source of carotenoids, vitamins, essential fatty acids, and some
protein and carbs, while at the same time you are getting some of the
benefits of water quality improvement from REASONABLE standing crops of
algal biomass harvested by the fish, either in the form of phytoplankton,
periphyton, etc. And certainly, I thought my comments were understood to be
framed within the context of operating costs and the economics of feed
ingredients, etc.
Ted Ground
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> From: James Rakocy, Ph.D.
> To: aquaponics@townsqr.com
> Subject: algal nutrition for tilapia
> Date: Thursday, February 05, 1998 1:54 PM
>
> Hello Everyone, I was just looking at some of our data and I've been
doing a
> lit. review concerning mamured and/or fertilized ponds as well as fed
ponds.
> You might find the results interesting. In our greenwater recirculating
> system (clarification only) that was choked with algae, including
periphyton
> (attached algae) and dead algae in a 1.4 m3 clarifier with only 15 male
Nile
> tilapia in it, the clarifier tilapia grew at a rate of 0.48 g/day
(initial
> weight was 71 g) while the open tank fish (28.6 m3 tank volume) stocked
at
> 26 fish/m3 which received ample floating pelleted feed (32% protein) grew
at
> a rate of 2.64 g/day, same initial weight. The clarifier fish did not get
> pellets. The data (courtesy of Bill Cole) was based on three
replications.
> So it seems that feeding to satiation with algae in this system produces
> only 18% of the growth rate that can be achieved with a concentrated dry
> (91.1% dry matter) feed pellet. With algae, fish eat a lot of water which
> must be voided, which cuts their daily dry matter intake and requires
energy.
>
> Now in ponds with manure and/or fertilizer, the best growth rates for
male
> Nile tilapia are about 1 g/day, often less. The fish are usually stocked
at
> 1-3 fish/m3. Studies show that the main value of the manure is for the
> inorganic nutrients it releases for algal growth. With feed or feed and
> fertilizer the growth rate will go up to about 3 g/day, but sometimes
much
> less. This is a vast simplification that not does not consider many
factors
> such as water quality. But here again the algae-based system only
produces
> about 33% of the growth rate obtained with feed. The densities were much
> lower than the greenwater tanks but there was no supplemental areation to
> improve water quality as in the heavily stocked greenwater tanks.
>
> Now in our aquaponic tanks just a couple weeks ago we achieved an average
> growth rate for male red tilapia of 3.7 g/day at a stocking rate of 143
> fish/m3, but the water quality was excellent, no pure oxygen though. In
the
> past with male Nile tilapia at 89 fish/m3 in an aquaponic system, we
> obtained growth rates of 4.9 g/day.
>
> What does this all mean? It means that algae is a fine food for tilapia
if
> it comes free or at low cost and you can live with low growth rates. If,
> however, you are paying dearly for heating, aeration and pumping, have a
> limited amount of space, and would like to recoup some of your output by
> selling the fish, you better stick with concentrated fish feeds and
forget
> the algae. I'm braced for the critiques. Jim Rakocy
>
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| Message 3 |
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Subject: MANURE- BREAK OUT THE HIP WADERS
From: "Ted Ground"
Date: Sun, 8 Feb 1998 06:52:43 -0600
Dear Aquaponics Folks and Organic Enthusiasts:
I have some comments on the overall issues of manure and microbiological
safety in aquaculture in general and aquaponics specifically. I would like
to preface my comments by introducing myself. My name is Ted Ground. I
have a B.S. and M.S. in Aquatic Biology. My field work as an undergrad
focused on plankton ecology. My masters thesis was on plankton nutrients
and biomass in reservoirs and how it all relates to water chemistry. I
spent most of my career as an analytical chemist, laboratory manager, and
water quality specialist. I worked for several years with a waste water
treatment division of a major city, where I received 100 hours of college
course work toward a waste water treatment operators license, and where I
analyzed compost and municipal sludge for years, and where I studied water
quality in a greenhouse system with water hyacinths, reed beds and algae,
used to polish waste water discharged back into the river. So I know a bit
about anaerobic digestors, municipal sludge, compost, and biological
treatment of wastewater. I founded and operated a food testing
(microbiology and nutrition) commercially laboratory business, and received
training from the National Marine Fisheries Service in Hazard Analysis and
Critical Control Point (HACCP) food processing safety planning. I have
several years experience as an aquaculturist. I have designed and operated
a wide variety of biofilters, greenhouses, and nitrifying bacteria and
algae cultures, and I currently own and operate a newly located and
upcoming organic farm and aquaponics greenhouse. I know a bit about water
quality, microbiology, organic farming, phytoplanton nutrient dynamics, and
water chemistry. I also like to cook and eat food and enjoy life whenever I
can. I am an omnivore. I eat fish, shrimp, pork, meat, grains, vegetables,
just about everything but compost- YUM!.
Now, pardon me if I flame, cause this is just what the following rant and
rave is going to be, so you can just delete this right now if you wish, but
I have been watching on the sidelines of this email group too long, now.
First of all, I would like to address what I detect as an unfounded
assumption or an implication that only anaerobic digestors can be relied
upon to preclude pathogens. This is simply not true. The assumptions
behind this perspective might come from the belief that the combination of
anaerobic conditions, with heat, along with competitive exclusion by the
microbes present in anaerobic digestors will eliminate pathogens. That is
something I can generally agree with- the facts. However, these same
elements may be found in soils, biofilms, composts, human and animal
intestines, and other biological systems, although not always in the same
intensity or in the same ratios.
For example, those of you who might think the heat of aerobic composting is
the only factor which eliminates pathogens there- I have news for you- it
is not the heat alone- some thermophilic opportunistic pathogens might do
well or at least survive within aerobic compost temperature ranges- rather,
it is a combination of heat and competitive exclusion by "good" bugs that
can reduce a lot of pathogens. Related to this topic of "good" bacteria,
we have to admit that in one gram of "healthy" "organic" soil, we have 3 to
500 million bacteria, 1 to 20 million actinomycetes, about 1 million fungi,
about 1 million yeasts, about a half million protozoa, about a half million
algae, and maybe 5000 nematodes. Within each of these groups are dozens if
not more genera, species, and strains, and many, such as Pseudomonas
bacteria, for example can be both good bugs and opportunistic pathogens.
So the entire planet is full of good-bad bugs under our feet and blowing
through the air that could potentially kill us- IF- and that is a BIG IF-
we ate a pound of dirt or rubbed an open, bleeding wound with compost, or
took a bath or an enema with compost tea. Yet there are about 5 billion of
us humans on this planet and we seemed to thrive in spite of all this scary
stuff around us. I grow weary of the voices of fear that seem to be
prevailing out there that would portray the commonplace things of nature as
impending doom. These people are afraid to live or something. Most of
them seem to be bureaucrats, academicians, hypochondriacs, political
extremists, or politicians, and their shrill cries reveal that they are
desparately trying to justify their existence.
Now, I am not advocating taking a macho, bullet-proof, or careless attitude
about raw manure. Terrestrial animal raw manure should not be applied to
garden soils in my judgement, because swine, poultry, and cattle may harbor
many parasites, influenza viruses, and other bugs that could harm us if we
are not careful- even so, common sense as well as good science shows us
that if you wash the vegetables, as well as your hands, as most of us do,
both on the farm and in the kitchen, then the pathogens that might have
splashed up onto leafy vegetables are generally eliminated- even if you put
"night soil" (raw human feces) onto the dirt as they do in the Orient. By
the way, much of the fruit and vegetable food poisonings in this country
are not related to what went into the soil that grew the crop- almost
always it comes from unsanitary handling (harvesters or packagers with
human feces on their hands or equipment) and storage conditions (rodents,
insects, dirty water leaking on packages, etc).
But what about manure and aquaculture? Wyban (1987) found that applying
the right amount of raw cow manure to shrimp ponds resulted in enhanced
productivity in the pond, along with no detectable fecal coliforms in the
water and no Salmonella in the shrimp. Why? Because the complex microbial
community present in the water column and in the sediments of the dirt pond
acted like a rapid aquatic composting community, competitively excluding
those "common indicators" of pathogenic bacteria. The raw manure fertilizes
the water and stimultes algae and (beneficial) bacterial production. The
algae and bacteria, in turn, serve as the base of the food chain in the
pond. This approach has been used for generations by the Oriental and
Middle Eastern cultures. Now, don't get me wrong- I am NOT advocating raw
terrestrial animal manure applied to closed recirculating systems such as
aquaponics. But I will take a stand against any claims that fish feces and
terrestrial animal feces are microbiologically similar. They are not.
Whereas certain kinds of coliforms may be detected in some kinds of fish
intestines, fish ponds, fish poop, we know that not all coliforms are the
same- the soil is full of coliforms, folks, so if you find coliforms in the
water, it could have come from the dirt upstream, not the fish. And not
all fish poop is the same. The intestinal microflora of Tilapia differs
from that of catfish or other carnivorous fish like the salmonids. I am not
saying fish are microbiologically risk-free to humans- they can give us
problems with Strep, Vibrio, and other things, but here is the point:
Aquaponics is no different in principal than if an organic farmer irrigates
his soil in his field (which is lousy with bacteria) from a surface water
source that happens to have fish in it. I know a number of organic farmers
that irrigate their crops from pond water or creek water, and they might
add a little fish emulsion or kelp meal extract, if they wish, to the
pressurized irrigation water line, and thus they "fertigate" their organic
crops. Nobody gets sick or dies from this common practice, in and of
itself. Now you can insist that Aquaponics is "manure" based if you wish,
but on face value that would mean that all those farmers, organic or
otherwise, that happen to irrigate their field crops with surface water
where fish happen to live are applying "raw manure" to their fields. How
SHOCKING!! Call the TABLOIDS!! You can see the absurdity of that position.
Admittedly, aquaponics tanks are more nutrient rich than some surface
waters you might find- but not much, otherwise the fish could not
sustainably grow in them. Aquaponics tanks are much like eutrophic lake
water- rich in nutrients and organic matter, but not so rich that you have
hypereutrophic conditions of anoxia, reducing conditions, low oxygen, low
pH, hydrogen sulfide, etc. And the pea gravel, sand or perlite beds are
analogous to wetland or marsh soils, or trickle filters in waste water
treatment plants, etc., in which a wide variety of microorganisms live on
biofilms in great abundance, thus competitively excluding the pathogens.
Peter Edwards (1991) reported in World Aquaculture that if any disease
hazards exist in integrated agriculture production systems, they are by far
most likely to come from the mixing of swine and/or poultry production on
farms, rather than from integrated fish production. This is established
microbiological and virological fact. Furthermore, let's be practical- it
is not as if the plants in an aquaponics system are packed in a slurry of
feces. The roots of the plants are grown in a media which filters the
water. There is a small but continuous amount of nutrient enriched water
continuously or intermittently supplied to the roots, and a good deal of
beneficial microbial activity takes place in the fish tank prior to being
delivered to the growing beds- so the fish feces settle out or are
processed and filtered in various stages prior to the final nutrients
reaching the plant roots. I know of no aquaponics operation that sprays
fish feces solids directly onto the edible portion of the plant- it just
doesn't happen that way. Hmmm. might not be a bad idea. Maybe I'll try it:
FISH FECES FOLIAR FOOD.
Just kidding. Maybe.
Consider what is acceptable organic farming practice right now for open
field crops- it is perfectly all right to apply bat guano (uncomposted),
sea bird guano (uncomposted), worm casings (uncomposted worm poop), fish
emulsion, blood meal, feather meal, etc., etc., etc., onto the soil. No
harm comes to the folks that eat the delicious organic vegetables grown in
this manner. Why? Well, because the microbes that might be pathogenic in
those materials are few in comparision to the beneficial bugs in the soil,
and the produce is washed in some way before going to market, for crying
out loud!
The point I am driving home is that we as a people should be courageous and
not a bunch of weak, whining, wimps, scared of our own shadow. We should
be reasonable in our concerns and precautions and critical in our thinking,
testing all things in the light of reason. People that are driven into
paroxysms of fear about some risk factor that is about as statistically
likely as a lightning strike or a meteorite falling into their living rooms
are, at times, the same people that don't give a second thought about
getting in their cars after drinking a few beers, as they go out on the
freeway where macho dung head Neanderthals and their air-headed sorority
sisters are racing mindlessly into road rage and certainly high
(statistically) incidents of death and destruction. For Pete's sake, let's
get some perspective and proportion, here. If you want to be scared of
something, take a look at what your state and federal government and the
USDA are doing with our tax dollars while struggling family farmers break
their backs trying to grow good food for people to eat.
O.K., I promise I will flame no more- until next time. My spleen has been
vented.
Sincerely Yours in Friendship,
Ted
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| Message 4 |
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Subject: Re: MANURE- BREAK OUT THE HIP WADERS
From: "H.Doelle"
Date: Mon, 09 Feb 1998 08:56:20 +1100
Dear Ted,
It is amazing in our society, that some people think others are always
wrong, because they either attack practitioners or academics or vice versa.
Do we ever learn NOT to knock each other, but work together ?
If you would have read my comments more carefully, I emphasised at the
beginning that nature has cycles of matter, which we have disturbed and must
be regenerated.
You are totally wrong to assume that soil can handle pathogens. Not todays
pathogens anymore.
What you practitioners forget, today eating habits of man and animals are
different from 40-50 years ago. Thus we have to be more careful.
Furthermore, neither anaerobic digestion nor composting kills ALL pathogens,
but they reduce them to a level, nature can cope with within its cycles.
IT IS VERY DANGEROUS TO MAKE STATEMENTS IN AN AEREA ONE HAS NEITHER STUDIED
NOR WORKED IN.
Have you as an analytical chemist ever studied in details effluents for
anything else than just E.coli ?
WHY DO WE TEND TO SEE ONLY BLACK AND WHITE ! There are some colour shades in
between. Nobody ever said you must kill all pathogens, You never can, but
you can do your best to reduce the risk.
WHY DO WE IN OUR COUNTRIES HAVE SUCH A HIGH WATER QUALITY REGULATION ?
Because we are afraid and know that effluents from human and animal wastes
(sewerage systems) my not be low enough in pathogens.
Let us be realistic and put health before economy or money !
Caution is the mother of all things in life.
Fortunately I have been an academic as well as a practitioner and thus have
a good idea of both sides, but find it hard to understand why they have to
attack each other instead of trying to understand each other for a common
save goal.
Whatever people are saying, the term organic farming or organic
fertilisation was created with the use of compost in the field. NOT MANURE !!
Manure was used when somebody remembered that in our youth and before,
grandfather used the septic and fertilised the field. That is totally
different from commercialisation of this method. Where it was
commercialised, it is now being realised as dangerous (e.g. China) and the
general trend is towards anaerobic digestion.
It is very unfortunate that aquaculture in some areas of the world adopted
the old method without realising the dangers in todays world of antibiotics,
hormone etc in our or animal food not only for the fish, but also for the
pond effluent !
Does your pond effluent comply with the strict standards of US water quality
standards, so you can put it into your recirculation system for drinking
purposes ? I am sure not if you use raw manure.
Please let us be reasonable in our debate and not only see black and white.
My aim is to reduce health risks in all areas of food production, as food
disease outbreaks appear to be on a sudden increase.
Best regards and wishes
Horst Doelle
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
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