I live near Handsworth park, Birmingham and have 2 sewage ponds nearby. The first pond coming out of the pipe seems anaerobic, with only an algae bloom, and the last pond smells foul, gives my dog diarrhoea, and is full of worms, shrimp and mosquito larvae. I am trying to clean the ponds for the public good. I bought 20 koi and put them in the final pond and they came up gasping for oxygen. So I put elodea and lilies into the pond. All seem to be thriving.

My question is can I oxygenate the anaerobic pond with elodea and lilies and put fish in there?

Dear Paresh,

very interesting!

But too much information for me to understand it completely. In a superficial way I knew about this system because a man I knew studied this in sweden in the 60s. So it is (was) known in europe too....

But what we do in europe up to now is the construction of very expensive sewage plants. It all startet with mechanical, biological and chemical cleaning stages. But now they add a stage for microplastic, a stage for pharmaceuticals and try to save at least phosphorous out of the sewage. The whole system becomes expensive and technically vulnerable at the same time. And due to climate change, including higher amplitudes of daily and weekly rainfall, it will become very demanding to run this complicated system in a propper way. Not to mention the high energy demand. And no manager of a plant like this will ever claim his plant is running perfect. Today it is estimated that 10-20 % of the nutrients end up in the ocean during the year. Assumed the plant is working correctly.....

No chance to transfer our high tec system as a solution for the whole world. So we need different and more sustainable solutions, created under locally given conditions.  And the multi barrier approach as shown here in the wetlands is a topic in this forum anyway. 

So to me it is a very interesting system and I rather see the possibilities than the limits. But industrial wastewater could be a threat if poured completely unprocessed into the system.

Would like to read other opinions.....

Heiner

Dear All,
Sharing a recent  piece that discusses the history of the East Kolkata Wetlands Bhaskar mentioned in their post dated 27th Jun 2014. The piece also briefly discusses the process employed by one of the  fish farmers; copying the relevant points below:

• Converting black wastewater to clear water in fishponds is the miracle of the East Kolkata Wetlands. This alchemy, which challenges the conventional scientific wisdom of wastewater as a pollutant, is produced by the intersection of labour, sunlight and fish.
• Munda is a second-generation fish farmer, now in his late 50s. He prepares his pond before releasing fish eggs into it, draining water out through a pipe during the winter, then cleaning, ploughing and mixing the exposed bed with lime, before scattering the seeds of a shrub called prickly sesban. A few months later, when the plant has grown to about 6ft, Munda opens up the incoming pipe to the canal and fills his pond, submerging the plants with wastewater and setting in motion a complex interplay between algae and bacteria.
• The wastewater, which is composed of nutrients such as nitrates and phosphates, and faecal matter containing aerobic bacteria, enters the fishpond. There the water submerges the plants, enabling them to produce algae as they rot. The algae photosynthesise to emit oxygen, which the aerobic bacteria then use to break down the nutrients in the sewage. This process releases carbon dioxide: the algae consume this and so proliferate. Within a few days an algal bloom drapes the surface of the pond in a luxuriant green. The bloom radically improves the quality of the water by oxygenating it, and also produces what Munda refers to as “maacher menu”, a buffet of plankton for the fish. Tiny fish are then released into the water to feast on the plankton and other nutrients, and their gorging cleans the water further.
• Another plant, the water hyacinth – which in the popular imagination is vilified as an invasive interloper from the Amazon – also works as a tireless purifier of waste. Though ecologists decry it in research papers, unlettered fishpond workers have long used the plant to their benefit. Lining the rim of a pond with water hyacinths protects the banks from erosion. The roots of the water hyacinth absorb heavy metals such as lead and mercury, along with excess nitrogen and potassium, which helps to clean the wastewater.
• A research study in 2008, conducted as part of a project by the Asian Development Bank, estimated that the East Kolkata Wetlands had saved the city a total investment of $125m by treating the sewage at no cost,

A google scholar search indicates that there has been quite some research: Highlighting some that I could understand and comprehend below

• This  paper  finds that the levels of heavy metals in fish are below FAO's and WHO's  permissible limits and hence safe for consumption. The researchers however 
• This paper  found that the biodegradation rate at the wetland ponds is faster than lab conditions,  wastewater gets stabilized within 10 days of retention in the ponds
• This paper attributes the resilience of the system to the scale of operation, adaptive production strategies that optimise resource utilisation while minimising risks, self‐organisation among stakeholders and timely legislation and institutional interventions to preserve the natural character of the wetlands

I hope this sparks fresh discussion on the subject  

Regards
paresh

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 weak 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 ?

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.


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.


Please see Table 1.

I have extracted this table into an excel file

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.

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.

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.

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.

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.

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

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



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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?

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