Urban Fish Ponds: Low-Tech Sewage Treatment for Towns and Cities (opens in new tab)

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?

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."

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

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/

I wish more cities did this.

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/

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.

Solar-powered edition of this article:

https://solar.lowtechmagazine.com/2021/03/urban-fish-ponds-l...

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-dramaticall...

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/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.

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.

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