Can fish be grown in ponds into which the sewage is released? (aquaculture) - and health risks

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  • Bhaskar
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Can fish be grown in ponds into which the sewage is released? (aquaculture) - and health risks

(note by moderator: moved into a new thread as it's a separate topic)


Dear Mr Mwaniki

Can we give you a design to make a profit out of sewage.

This is possible if fish can be grown in ponds into which the sewage is released.

Income from sale of fish would be more than the cost of the pond and maintenance.

There will be no problem of harmful bacteria, etc.

The fish can either be consumed by people or used as fish meal in aquaculture ponds or as poultry feed.

Please confirm if fish can be grown in ponds using sewage.

Regards

Bhaskar
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I am working on a clean technology product to grow Diatom Algae in large waterways. Diatoms account for about 25% of all photosynthesis on Earth and hence are the best solution to consume CO2, N and P and oxygenate water and feed fish.

I am a Chartered Accountant but am now an entrepreneur focussed on clean technology.
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  • joeturner
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Re: Reply: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don?t have sewer connections (Kenya)

Dear Bhaskar, I am interested to hear that there are 'no problems with harmful bacteria' from aquaculture in sewage ponds. Can you point me to research which shows this, please?
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  • mwaniki
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Re: Reply: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don?t have sewer connections (Kenya)

Hi Bhaskar

Kindly note that The New York Times of Dec 15, 2007 carried an article entitled ‘Fish Farming in Toxic Waters in China. “Scientists had warned on the long-term risks of consuming contaminated seafood could lead to higher rates of cancer and liver disease and other afflictions” (verbatim).

More recently there have been reports of fish farmed in Asia and imported to the US have been raised on diets of chicken and pig feces.

I think these are violations of food safety regulations. Production and consumption of such seafood products should be discouraged anywhere on the planet.

Thanking you / Mwaniki
Am the publisher of the Africa Water,Sanitation & Hygiene and the C.E.O. of Transworld Publishers Ltd.,Nairobi-Kenya.
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  • JKMakowka
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Re: Reply: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don?t have sewer connections (Kenya)

joeturner wrote: Dear Bhaskar, I am interested to hear that there are 'no problems with harmful bacteria' from aquaculture in sewage ponds. Can you point me to research which shows this, please?


This classic booklet has some pointers what the risks are and how to manage them:
www.zetatalk10.com/docs/Sanitation/Aquac..._Technology_1985.pdf



+++++++++++++
Note by moderator, due to restructuring of a thread:

Additional questions to Bhaskar posed by Chris Canaday on 26 June:

Thank you, Bhaskar, for the suggestion of raising fish in the sewage. I would worry about:
  • the smell from open ponds in highly populated areas,
  • pharmaceutical chemicals, chlorine, etc.,
  • the effluent (or could it soak into the floor of the pond?)
What species of fish would you use?
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  • canaday
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Re: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don’t have sewer connections (Kenya)

Dear all,

Fish in open ponds of sewage in populated areas would likely stink too much, but there is a practice in Indonesia to put catfish into septic tanks and even latrines to eat the sludge and keep them from filling up too fast.
www.appropedia.org/Sewage_treatment_using_catfish
en.wikipedia.org/wiki/Clarias

They reportedly clean up the fish (over time in clean, flowing water) and eat them, but (once again) I would be worried about the pharmaceuticals and other chemical contamination. (The bacteria would be killed in the cooking.) I think it would be preferable to feed these to animals (not in our food chain) or bury them in the ground as fertilizer. In any case, these fish could potentially be a part of a low-cost option for treating water in Africa and elsewhere.

The Outlook Program of the BBC just interviewed an outgoing, creative, civic-minded rap musician from the Kibera slum in Kenya, who goes by the stage name of Octopizzo. He did not say anything about sanitation, but it would be great to enlist him to help campaign for UDDTs ... and he could talk about this on his TV show and maybe make a song.
www.bbc.co.uk/podcasts/series/outlook

Best wishes,
Chris
Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
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  • Florian
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Re: Reply: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don?t have sewer connections (Kenya)

Volume 3 of the WHO Guidelines for the safe use of wastwater, excreta and greywater is dedicated to Aquaculture: www.who.int/water_sanitation_health/wastewater/gsuweg3/en/

Volume 3 of the Guidelines informs readers on the assessment of microbial hazards and toxic chemicals and the management of the associated risks when using wastewater and excreta in aquaculture. It explains requirements to promote safe use practices, including minimum procedures and specific health-based targests. It puts trade-offs between potential risks and nutritional benefits in a wider development context. Special reference is made to food-borne trematodes.


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  • joeturner
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Re: Can fish be grown in ponds into which the sewage is released? (aquaculture) - and health risks

Section 3.1.1 seems to be important, but unfortunately I cannot copy the paragraph to discuss it here.

The paragraph I wanted to discuss says this:

However, when waste-fed fish are sampled in the market, they often show much higher levels of bacterial contamination in their edible flesh. This indicates that much of the bacterial contamination of fish flesh occurs during post-harvest cleaning due to cross-contamination with the gut contents or unhygenic facilities.


I don't think it is correct to state that there are no issues with pathogenic bacterial when rearing fish in faecal ponds.
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  • Bhaskar
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Re: Reply: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don?t have sewer connections (Kenya)

There is no formal research on this issue.
It is common knowledge that well oxygenated ( DO 5 mg / liter or more ) water is clean

Most harmful bacteria in water are anaerobic. When you grow Diatoms the DO can be maintained at a high level and this prevents growth of Anaerobic bacteria.

Not many have thought of specifically growing Diatom Algae.

This is one paper that says that Diatoms are good for sewage treatment.

www.int-res.com/articles/meps/3/m003p083.pdf

The Possible Importance of Silicon in Marine Eutrophication

"One, rather than considering treatment procedures which remove the nutrients nitrogen
and phosphorus from a sewage discharge into a eutrophied region, one might consider
the addition, if feasible, of silica in quantity at the discharge site to alter the
receiving waters to a diatom population and a consequent fertile and productive region."

We have found that dosing micro nutrients into sewage is a better way to grow diatoms.
Clean technology promoter.

I am working on a clean technology product to grow Diatom Algae in large waterways. Diatoms account for about 25% of all photosynthesis on Earth and hence are the best solution to consume CO2, N and P and oxygenate water and feed fish.

I am a Chartered Accountant but am now an entrepreneur focussed on clean technology.
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  • Bhaskar
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Re: Can fish be grown in ponds into which the sewage is released? (aquaculture) - and health risks

The concerns about harmful impact of bacteria in sewage proving harmful and foul odor are quite obvious.

1. Fish in intensive aquaculture ponds live in their own feces. There is not much of difference between fish and human feces. Sewage may of course contain industrial chemicals, disposables, etc.

2. Kolkata a large city of about 10 million people does not have a single 'modern' sewage treatment plant. All the sewage is released into the East Kolkata Wetlands and fish grown there are consumed by the people. Everyone who knows about India knows that Bengalies love fish.

www.keip.in/bl3/wetlands.php
About 12,500 hectares of wetlands are available to house 250 fish farms.
Not all cities have this much land.

There is no problem with the basic process of using sewage to grow fish, you just have to design the system to deal with the problems - odor, bacteria, etc.

One option is a conventional sewage treatment plant ( Aerobic or Anaerobic) that treats the sewage to bathing quality but does not remove the nutrients, N and P. Then the treated sewage meeting all regulatory requirements, but containing N and P, can be released into a fish pond without any problem.

Another option is to have a two pond system.
First pond to treat the sewage using our process - Diatoms and then harvest the diatoms and put these into another pond with fish in them. So the sewage does not flow from the first pond to the next, only the diatoms are transferred. Harvesting diatoms is difficult, so this is expensive.

Third option is to have 2 ponds, grow diatoms in the first pond, test the treated sewage to confirm if it meets the quality requirements and then release the treated sewage with diatoms in it into the second pond with fish. If necessary, you can have 3 ponds in series to get the desired quality in 2 ponds before releasing into the 3rd pond.

Diatoms require about 7 days to completely consume all the N and P in sewage.

Facultative Lagoons in USA have a retention time of 20 days+.
water.epa.gov/scitech/wastetech/upload/2..._15_mtb_faclagon.pdf

"The technology associated with facultative lagoons has been in widespread use in the United States for at least 90 years, with more than 7,000 facultative lagoons in operation today.
..
A recently developed physical modification uses plastic curtains, supported by floats and anchored to the bottom, to divide lagoons into multiple cells
and/or to serve as baffles to improve hydraulic conditions. Another recent development uses a floating plastic grid to support the growth of
duckweed (Lemna sp.) plants on the surface of the final cell(s) in the lagoon system, which restricts the penetration of light and thus reduces algae (with sufficient detention time > 20 days), improving the final effluent quality."

Similar ponds would be adequate.

Diatoms are far better than duckweed, since they are consumed by fish and grow in the entire volume of water and not just on the surface and any dead diatoms sink and do not float and prevent light penetration.

Our process of using Diatoms will solve 6 of the 7 disadvantages listed,

Sludge will be less since diatoms are consumed by fish - the organic matter becomes fish biomass not sludge,
Diatoms consume ammonia,
oxygen from diatoms promotes growth of aerobic bacteria,
diatoms prevent other algae and weeds from growing and the higher DO reduces mosquito larve,
the ponds can be deeper since diatoms require less light and sink on death,
Diatoms increase DO and prevent foul odor.

The burrowing animal problem will not be solved.
Clean technology promoter.

I am working on a clean technology product to grow Diatom Algae in large waterways. Diatoms account for about 25% of all photosynthesis on Earth and hence are the best solution to consume CO2, N and P and oxygenate water and feed fish.

I am a Chartered Accountant but am now an entrepreneur focussed on clean technology.
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  • Bhaskar
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Re: Reply: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don?t have sewer connections (Kenya)

Joe

The paper you posted is quite comprehensive, but does not mention Diatoms even once.

A list of papers about Diatoms and Fish are in the file attached.
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Diatoms are the natural food for many fish and crustaceans in nature.
Specifically growing Diatoms in sewage treatment ponds and fish ponds is a paradigm shift.

A paper about Principal Diatoms of Major Waterways of US is also attached.
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Please see Table 1.

I have extracted this table into an excel file
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and calculated the ratio of Diatoms to total Phytoplankton, the last 2 columns of the Table.

Diatoms account for 78% of the phytoplankton, this is the average for 1 year i.e., all seasons.

Chris

Tilapia, Carp, Catfish, etc. can be grown.
Tilapia may be best - they can digest sludge and they
consume Diatoms.
Clean technology promoter.

I am working on a clean technology product to grow Diatom Algae in large waterways. Diatoms account for about 25% of all photosynthesis on Earth and hence are the best solution to consume CO2, N and P and oxygenate water and feed fish.

I am a Chartered Accountant but am now an entrepreneur focussed on clean technology.

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  • Bhaskar
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Re: Reply: How to construct simple and inexpensive and efficient wastewater treatment systems plants for homesteads which don?t have sewer connections (Kenya)

Joe

Quote from Page 20 of the book cited by you -

"Stabilization ponds are recommended for treating sewage in the tropics since
they are cheaper to build and maintain than trickling filters and activated sludge
plants and are vastly superior from a public health point of view. A properly
designed series of ponds with a 'minimum detention time of 25 days can produce a
final effluent with no protozoa and helminth uva and only a very low survival rate
of bacteria and viruses. A series of conventional stabilization ponds normally
consists of an anaerobic pond, which functions like a septic tank to sediment
sewage solids, followed by facultative and maturation ponds. These latter two
contain large densities of phytoplankton suitable for feeding fish, but the
dissolved oxygen regime is normally suitable for aquaculture only in maturation
ponds. From a sanitary engineering point of view, anaerobic and facultative ponds
are designed for 5-day biochemical oxygen demand (BOD5) removal and maturation
ponds for pathogen removal, but the latter may be suitable for aquaculture. As
indicated in Fig. 9 there are various options for recycling sewage in a series of
stabilization ponds, which depend to a large extent on the strength of the raw
sewage. If the sewage is we&k or is diluted considerably, it may be added
directly to the maturation-fish pond. Dilution may be achieved by mixing with
unpolluted water or by adding only small amounts of raw sewage to the pond so that
the pond water itself is the major source of dilution water. Primary
sedimentation is normally used to remove sewage solids in both waste treatment and
aquaculture reuse, otherwise they would lead to a rapid sludge build-up in the
ponds."

This is almost same as what I posted above.

Why are we discussing the same fundamental issues even after 30 years ?
Clean technology promoter.

I am working on a clean technology product to grow Diatom Algae in large waterways. Diatoms account for about 25% of all photosynthesis on Earth and hence are the best solution to consume CO2, N and P and oxygenate water and feed fish.

I am a Chartered Accountant but am now an entrepreneur focussed on clean technology.
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