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Urban Fish Ponds: Low-Tech Sewage Treatment for Towns and Cities

31 points by MaurizioPz 6y ago

blakesterz 6y ago
Interesting story, but something about eating fish raised on sewage left me feeling kinda squeamish? I love how they market their book on this site: "The Printed Website: Second Volume Out Now The printed version of Low-tech Magazine can be viewed with no access to a computer or a power supply -- or when the solar powered website is down due to bad weather."
- reaperducer 6y ago
  something about eating fish raised on sewage left me feeling kinda squeamish? Then be sure to never eat catfish.
lostandbored 6y ago
Not surprised to see this posted here already. Anyways, I find the idea presented in the article really interesting, and I honestly can see this system being used in cities that are "Degrowing" to provide similar services on a slimmer budget, while providing job opportunities for locals, and a new industry for a city to increase income flow.
reaperducer 6y ago
This is already being done in many cities. Although, usually without the fish. When Vancouver built its athletes' village for the 2010 games, it included a large swale to clean the wastewater before it went back into the bay. In Las Vegas, after going through preliminary treatment, all waste water goes through a massive swale complex before returning to Lake Mead. The swale complex is known as Clark County Wetlands Park, and Lake Las Vegas. In Chicago, most new large skyscraper projects have to have stormwater handling systems. Very often these days they're going into natural treatments like public/private parks and landscaping. The reason for this isn't environmental, though. It's economic. Cook County has spent over $3 billion on its Deep Tunnel project which handles stormwater, and it's tired of spending all that money: https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan
raleec 6y ago
If you're interested in this, you should definitely check out Songhai [1] They try to recycle everything, from biogas and then aquaculture off of the sewage and agricultural run-off, to harvesting the maggots off of the food waste to feed the fish and poultry. Farm to Table to Farm. [1] http://songhai.org/ http://songhai.org/
oftenwrong 6y ago
Solar-powered edition of this article: https://solar.lowtechmagazine.com/2021/03/urban-fish-ponds-low-tech-sewage-treatment-for-towns-and-cities.html https://solar.lowtechmagazine.com/2021/03/urban-fish-ponds-l...
patall 6y ago
That is a low-tech solution for a low-tech world. There are studies that even with the current level of water treatment, some rivers contain 90% (or so) female fish, due to the remaining pharmaceuticals in the water. European cities are now starting level 4 water treatment with activated charcoal and ozon to improve the water further but even then, some substances will remain in the water. So maybe we can use the untreated water to grow plants for energy generation but I would be very skeptical of any food production.
yjftsjthsd-h 6y ago
I'd like to see more discussion of keeping this safe from pathogens; the article includes a handful of throwaway lines like "keeping bacterial loads to an acceptable level under WHO guidelines" and "let the untreated sewage water sit in primary and secondary ponds before mixing it into fish ponds, effectively killing harmful pathogens and allowing large solids to sediment", but I'd like a little stronger explanation for why this okay when we're talking about intermingling human waste with food supply, which I'm given to understand is avoided for very good reasons most of the time. How is this not begging for an E Coli breakout?
- gnat 6y ago
  As I understand it, chlorine and heat treatment are how pathogens are killed in waste-water treatment plants. E.g., https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Boundless)/17%3A_Industrial_Microbiology/17.3%3A_Wastewater_Treatment_and_Water_Purification/17.3B%3A_Wastewater_and_Sewage_Treatment https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_... If you're ever in Boston, the Deer Island Treatment Plant offers tours and they're fascinating. (The odour is only challenging for a brief part of the tour)
GeekyBear 6y ago
I've often thought that using human waste to feed the fastest growing water plants and then composting those plants would be a good way to recycle human waste and render it useful. Compost also manages to hang around in the croplands a lot longer than chemical fertilizer does. >Maps Show How Dramatically Fertilizer is Choking the Great Lakes https://returntonow.net/2020/12/11/maps-show-how-dramatically-fertilizer-is-choking-the-great-lakes/ https://returntonow.net/2020/12/11/maps-show-how-dramaticall...
aaron695 6y ago
In Cambodia there's a problem in the floating villages with children drowning at night when going out the defecate over water, but worse is of course is the many many children dying of diarrhoea from dirty water - https://www.theguardian.com/global-development/2017/feb/15/safe-toilets-help-flush-out-disease-in-cambodia-floating-communities-tonle-sap-lake https://www.theguardian.com/global-development/2017/feb/15/s... I see both arguments, perhaps creating a business model around making human waste worth money might create a solution. This has been looked at as a way to empty indoor toilets in India (vs open defecation) But I think treating it as toxic is the way forward. In the 1% countries 'Urban Fish Ponds' could/should mean wetlands. Ignore the environmentalists, we have weakened many eco-systems thought day in/out living, we need to give back the fundamental basis of life, water. Don't restore wetlands, create them in new places inland.
Fezzik 6y ago
I have made comments (or at least one comment) before regarding Silverton, OR that does something similar - they clean and zap all their sewage with UV light and then send it a few miles up the hill to a botanical garden to filter through a multi-acre wetland complex because the water is a bit too hot to immediately introduce back in to the watershed. The wetlands complex is an entirely manmade mini-ecosystem that is home to tons of native plants and animals and works to cool the water before it goes back in to a native stream. It also provides “free” water for the botanical garden. I worked there through AmeriCorps in 2006 and it is a really cool setup: https://www.oregongarden.org/ https://www.oregongarden.org/ I wish more cities did this.
aitchnyu 6y ago
So floating plants draw out heavy metals and they are fed to livestock. That's bad, amirite?

31 points by MaurizioPz 6y ago

Interesting story, but something about eating fish raised on sewage left me feeling kinda squeamish? I love how they market their book on this site: "The Printed Website: Second Volume Out Now The printed version of Low-tech Magazine can be viewed with no access to a computer or a power supply -- or when the solar powered website is down due to bad weather."

reaperducer 6y ago
something about eating fish raised on sewage left me feeling kinda squeamish? Then be sure to never eat catfish.

lostandbored 6y ago

Not surprised to see this posted here already. Anyways, I find the idea presented in the article really interesting, and I honestly can see this system being used in cities that are "Degrowing" to provide similar services on a slimmer budget, while providing job opportunities for locals, and a new industry for a city to increase income flow.

reaperducer 6y ago

This is already being done in many cities. Although, usually without the fish. When Vancouver built its athletes' village for the 2010 games, it included a large swale to clean the wastewater before it went back into the bay. In Las Vegas, after going through preliminary treatment, all waste water goes through a massive swale complex before returning to Lake Mead. The swale complex is known as Clark County Wetlands Park, and Lake Las Vegas. In Chicago, most new large skyscraper projects have to have stormwater handling systems. Very often these days they're going into natural treatments like public/private parks and landscaping. The reason for this isn't environmental, though. It's economic. Cook County has spent over $3 billion on its Deep Tunnel project which handles stormwater, and it's tired of spending all that money: https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan

raleec 6y ago

If you're interested in this, you should definitely check out Songhai [1] They try to recycle everything, from biogas and then aquaculture off of the sewage and agricultural run-off, to harvesting the maggots off of the food waste to feed the fish and poultry. Farm to Table to Farm. [1] http://songhai.org/ http://songhai.org/

oftenwrong 6y ago

Solar-powered edition of this article: https://solar.lowtechmagazine.com/2021/03/urban-fish-ponds-low-tech-sewage-treatment-for-towns-and-cities.html https://solar.lowtechmagazine.com/2021/03/urban-fish-ponds-l...

patall 6y ago

That is a low-tech solution for a low-tech world. There are studies that even with the current level of water treatment, some rivers contain 90% (or so) female fish, due to the remaining pharmaceuticals in the water. European cities are now starting level 4 water treatment with activated charcoal and ozon to improve the water further but even then, some substances will remain in the water. So maybe we can use the untreated water to grow plants for energy generation but I would be very skeptical of any food production.

yjftsjthsd-h 6y ago

I'd like to see more discussion of keeping this safe from pathogens; the article includes a handful of throwaway lines like "keeping bacterial loads to an acceptable level under WHO guidelines" and "let the untreated sewage water sit in primary and secondary ponds before mixing it into fish ponds, effectively killing harmful pathogens and allowing large solids to sediment", but I'd like a little stronger explanation for why this okay when we're talking about intermingling human waste with food supply, which I'm given to understand is avoided for very good reasons most of the time. How is this not begging for an E Coli breakout?

gnat 6y ago
As I understand it, chlorine and heat treatment are how pathogens are killed in waste-water treatment plants. E.g., https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Boundless)/17%3A_Industrial_Microbiology/17.3%3A_Wastewater_Treatment_and_Water_Purification/17.3B%3A_Wastewater_and_Sewage_Treatment https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_... If you're ever in Boston, the Deer Island Treatment Plant offers tours and they're fascinating. (The odour is only challenging for a brief part of the tour)

GeekyBear 6y ago

I've often thought that using human waste to feed the fastest growing water plants and then composting those plants would be a good way to recycle human waste and render it useful. Compost also manages to hang around in the croplands a lot longer than chemical fertilizer does. >Maps Show How Dramatically Fertilizer is Choking the Great Lakes https://returntonow.net/2020/12/11/maps-show-how-dramatically-fertilizer-is-choking-the-great-lakes/ https://returntonow.net/2020/12/11/maps-show-how-dramaticall...

aaron695 6y ago

In Cambodia there's a problem in the floating villages with children drowning at night when going out the defecate over water, but worse is of course is the many many children dying of diarrhoea from dirty water - https://www.theguardian.com/global-development/2017/feb/15/safe-toilets-help-flush-out-disease-in-cambodia-floating-communities-tonle-sap-lake https://www.theguardian.com/global-development/2017/feb/15/s... I see both arguments, perhaps creating a business model around making human waste worth money might create a solution. This has been looked at as a way to empty indoor toilets in India (vs open defecation) But I think treating it as toxic is the way forward. In the 1% countries 'Urban Fish Ponds' could/should mean wetlands. Ignore the environmentalists, we have weakened many eco-systems thought day in/out living, we need to give back the fundamental basis of life, water. Don't restore wetlands, create them in new places inland.

Fezzik 6y ago

I have made comments (or at least one comment) before regarding Silverton, OR that does something similar - they clean and zap all their sewage with UV light and then send it a few miles up the hill to a botanical garden to filter through a multi-acre wetland complex because the water is a bit too hot to immediately introduce back in to the watershed. The wetlands complex is an entirely manmade mini-ecosystem that is home to tons of native plants and animals and works to cool the water before it goes back in to a native stream. It also provides “free” water for the botanical garden. I worked there through AmeriCorps in 2006 and it is a really cool setup: https://www.oregongarden.org/ https://www.oregongarden.org/ I wish more cities did this.

aitchnyu 6y ago

So floating plants draw out heavy metals and they are fed to livestock. That's bad, amirite?