ARTICLES      
         
         
         
  The use of chemical
fertilizers is a part of
an unnatural linear
flow of nutrients that
human societies have
adapted themselves to
since we discovered
the fossil fuels

Aquaponics as an example of a sustainable and holistic perspective or Is this the making of a sewage revolution?

The use of chemical fertilizers is a part of an unnatural linear flow of nutrients that human societies have adapted themselves to since we discovered the fossil fuels. This temporary resourse has given us the opportunity to (for a while) keep taking from the larders, without replenishing them again. The flow moves from phosphorous mines, that one day will be empty, and energy-wasting nitrogen fixation, past plant production, meat production, humans, and into the sewage. The sewage then becomes a problem in the other end. However much we would like to believe that our treatment plants are doing a completely good job, they do miss some parts of the nutrients that become pollution because there’s too much of them in the wrong place in nature’s cycles.

Furthermore, there is a fundamental fault in the thinking in that system. The treatment plants are made to send the nitrogen, this important ingredient in nutrition, back up into the air, instead of keeping it in a form that the plants can readily use. That is what we ought to be putting back in the larder!
There are many ways that could be done, one of them is how fish come into vegetable farming:

In an aquaponic system, you don’t have to import any nutrients for the plants, and you are not harming the environment with the byproducts of the fish. But there is one input – fish food – and one output – human food. In nature, such loose ends are always linked in some way. There are no linear flows in the cycle of nutrients, everything will come around again, in some way. Let us make a thought experiment, that if used, could practically be a sewage revolution.

Here we have two loose ends: fodder in, and sewage out.

If we add sunshine, and use the sewage water to grow algae, the algae could be food for zooplancton, which in turn will be food for small crustaceans. Which in turn are perfect food for our fish! Or for crayfish, giant shrimp, mussels, or other aquatic animals that humans can eat. And they will all give excretions that nourish our vegetables.

In this thought experiment, many of you have by now started thinking about the unwanted substances in sewage water, that we certainly do not want to consume in our part of the cycle. Great!
In this thought experiment, many of you have by now started thinking about the unwanted substances in sewage water, that we certainly do not want to consume in our part of the cycle. Great!
The rests of contraceptive pills that women pee out are hormones that can make fish infertile and double-sexed. Low sperm counts have been measured in men, who got their share of their girlfriend’s pills through the tap water. And antibiotics, heavy metals, pathogens – not all of this is in fact cleaned in the sewage treatment today. It is harming nature, and it is harming us – but the link between cause and consequense is not obvious.
In a local nutrient cycle, an aquaponic system where the nutrients from human excretions come back to the fish via algae, more people will notice that we have a problem we need to solve. Aquaponics does not create this problem, but it can become the eye-opener that makes us decide to deal with it.

I talk about these nutrient cycles as local. It is because I see some problems in a large scale centralised system. Partly because there are costs involved in transporting the sewage to the treatment plant. But also because we end up with large amounts of nutrients far from the places where they can be used again, and to avoid pollution at the end of the pipe, they must be distributed to places where they are needed.

Built into a sewage cleaning system, wheter it’s local or centralised, there must be processes, biological or other, that can kill pathogens, bind and remove heavy metals, and break down medicine rests so they can not have unwanted effects on living organisms. As biological processes for this, in a local cycle, some candidates could be mosses, worm composts and effective microorganisms (EM).

There is another little detail we might consider how we could fit into this cycle – could we produce and collect biogas somewhere along the line?

In this lake the fish is so full of quicksilver that I can use it as a thermometer!

   

 

    [2012-02-07]
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