Updates & new experiments

While I performed the experiment growing cucumber with wood ash and iron as supplementation, I got an early indication that still something was missing in terms of nutrients. To make matters worse, chelated iron is not an easy product to come by and has a big energy and carbon footprint since it must be mined, refined, transported, packaged, transported again, etc. Even if this experiment would show great results, I would need to find a better substitute to supplement iron and other micronutrients.

As part of my hobby I am also interested in composting and vermicomposting. A while ago after having run a small home vermicompost system, I decided to collect the liquid that is produced in the bottom of a vermicomposter (known as vermicompost leachate), filter it, let it stabilize and then analyze it for some compounds. The results I found were:

These results seem to indicate the potential to use vermicompost leachate as a complement to urine. I therefore decided to start a small trial to test this hypothesis. The experiment was set up as an Nutrient Film Technique (NFT) system, connected to an MBBR with nitrifying media. The NFT returns water to the MBBR via a funnel (see image)

There was only one air pump powering all of the system. The idea was to reduce energy consumption by having the air pump oxygenate the water, mix the media, and pump water to the beginning of the NFT through the airlift principle (In the image, white tube is the outlet of air pump, black tube is inlet of airlift)

Five lettuce seedlings were added (the ones on the far left didn’t survive due to bad positioning) and the system was added an unspecified amount of urine and vermicompost leachate to test the concept.

After two weeks, the observed growth was substantial, and there were very little defficiency signs in the leaves of these different lettuce plants.

Of course, lettuce plants have substantially less nutrient requirements than fruit plants, so the next step will be to calculate the amounts of wood ash and vermicompost leachate to add in order to theoretically meet the nutrient requirements of, for example, cucumber, and set up the experiment in the three media bed systems to try and determine the best dosage of vermicompost leachate.

On a subjective note, the lettuce grown in this set-up tasted better for me than the ones grown only with urine in the first anthroponics trial (see here)

An overview of Anthroponics

The following image intends to depict the current planned research in this new field of anthroponics, as well as the topics of research which I have already covered. The images in blue are the ones planned but not executed. The ones in white are the topics that have been executed in some form or another, as a proof of concept or resulting in a technical report. The one in red was an experiment that did not yield any positive results as a proof-of-concept.

 

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As you can see, this new field of anthroponics can have many different branches. The first main categories relate to the source of nutrients, from the type of human waste used (urine only, feces only, or combined). In this regard, the last two are purely theoretical. The first one can be influenced by parameters which I have not had the opportunity or resources to test for its effects, such as the impact of a different diet as well as collecting from different individuals.

The second main category relates to the treatment of urine prior to its use in an hydroponic system. My method has been focused on the ammonia volatilisation from urea (AVfU), but another researcher in Hong Kong has been experimenting with lactic acid fermentation. Once he has some recorded results or when I perform my own experiment, such information will be shared in this website as well. Unlike AVfU, lactic acid fermentation reduces the pH to 3-4 while preventing bad odors. However, it is still unclear if the resulting liquid can grow plants hydroponically.

In the case of AVfU, the next step is the method of transforming the fresh urine into aged urine. While I have experimented with both alternatives, I have yet to try other catalysts such as jack beans (or even others). The resulting liquid, named “hummonia” (human + ammonia) can be used in many different system configurations, but a precise analysis of the liquid, in terms of its nutrient composition, the presence of microorganisms, persistent organic pollutants or even heavy metals has not yet been performed.

Of all the different system configurations possible, and experiments possible in those systems, the most complicated and potentially impossible one might be the passive system. A passive anthroponics system would have entail a pathway that does not require the energy requirements of an aerobic process or recirculating process. Given my current understand of the processes used in anthroponics, such as nitrification and AVfU, it might not be possible to have a working anthroponics system without the use of an air pump, a water pump, or some sort of mechanical agitation of the liquid.

Wrapping up the decoupled anthroponics experiment

Here are some pictures showing the recovery of the basil and coriander. After controlling the pH by adding phosphoric acid (in the DWC component) and wood ash (in the biofilter component), as well as adding some chelated iron in the DWC component, the plants have recovered dramatically.

The next step will be to harvest the produce, write a small technical report about this proof of concept, and do it again with the lessons we have learned from the pH drift and lack of nutrients.img_20161201_184425img_20161201_184434

Healthy roots growing in the DWC component, with a small airstone for oxygenation, and weekly dosage of the urine after ageing and biofiltration.

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And without the LED lights on:

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