Using plants to purify water by removing nutrients and Carbon Dioxide is a known method. Macrophyte harvesting is known to remove nutrients from ponds, ditches and other water bodies. Aquatic plants are also used in waste water plants to purify water so that it can be reused. So combining waste water treatment and growing vegetables sounds like a good combination.
In 2016 I had some left over germinated lettuce that I placed in a small aquarium with aquatic plants and gastropods. A small lamp that stimulates photosynthesis luminated the aquarium. Due the algae development it looked like a nutrient rich environment. The next weeks the roots grew through the floating filtration material and the plants grew to lettuce plants with 2 large leaves. This simple aquaponics system seemed like a good environments. Eventually all leaves reached a size between the 8 and 10 centimeters and I had to fixate the filtration material to the sides to prevent it from sinking.
It took a while before I realized that I was experimenting with a non circulating hydroponics system only not with an added nutrient solution but nutrients that were produced by gastropods and decomposing materials. Most hydroponics systems are circulating systems that depend on water pumps and technological parts making them vulnerable for various forms of system failure. The Kratky method however is non-circulating hydroponics system that doesn't depend on pumps and electricity.
Instead of using a bucket with only nutrient enriched water I started using waste water as nutrient solution. I also started using nutrient pour gravel like materials as soil simulants such as used in lunar soil experiments. In my lab the plants are placed under a 15 watt lamp that is specially designed for plant growth. The plants that developed in this setup displayed good root and leave development. Until now this looks like a acceptable setup that I will keep improving. As with various plants the size of the space for the roots will limit the growth of the plants. The next step is to test how large the plants must grow to produce vegetables.
The setup I use was inspired by a tomato growing setup on board the International Space Station. Until now I'm satisfied with the startup of this project that is still in the early stages of development. At this moment I'm still experimenting with lettuce, tomatoes and peppers and trying to find out which size of container those vegetables need to grow to a good size. For the tomatoes ang peppers I also have to find out at what size the are large enough to produce vegetables in a limited space. Eventually I want to produce various vegetables in a space that is as small as possible.
