Waste Recycling Tomato Pods

Is waste the future?

With climate change and the world turning to new sustainable alternatives of producing energy and recycling materials, we as designers should be thinking of new ways of reusing waste and using resources available to us. Human waste has many uses and should not just be flushed down the toilet and sent away to the sewers. It should be returned back to the soil with all it’s nutrients to help grow food, instead of the use of chemical fertilisers.

Both urine and faeces are useful resources in their own ways but have to be separated out. I have designed a toilet and system which splits the two.

Human excrement if kept in anaerobic conditions in a sealed container will start to produce methane. The higher the temperature, the faster the material decomposes, and the higher the rate of production of methane gas. This methane can be used as an energy source.

Urine can be diluted to make a natural fertiliser which should be applied directly to the root system of the plant. It is best to do this immediately or within 24 hours to ensure that ammonia is not released which causes it to smell. However animals will be able to detect the smell and hence it acts as a natural animal repellent.

Urine fertiliser is particularly beneficial for plants which require a lot of nitrogen to grow like tomato plants.

I was inspired by the unusual, striking form and scale of the baobab trees, native to Africa. They are sometimes referred to as “the upside down tree”. They swell up drawing in all the water they can, storing it inside their trunk like a water tank, to ensure they will survive in the dry months.

I explored ways of achieving this swelling geometry on Grasshopper, and used the plugin called Fattener to grow the shape in different areas, controlled by separate parameters.

I then unravelled this radial shape, and tested other options to see which one received the most sunlight all year round.

The toilet pods needed to have the right balance between privacy for the users, and receiving the most sunlight for the tomatoes. I used expressions on Grasshopper to cull the faces of the mesh in a certain way to make sure the parts of the pods that you could see into were made from timber, and the other parts would be made from bio-polycarbonate to let in sunlight for the tomatoes.

Instead of this stepped geometry achieved from culling faces, I added veining with the new Rhino 7 multipipe tool and separated the geometry this way.

Using the plugin Anemone with Grasshopper, I analysed the how the rain would fall on the pods and the overhang to collect rainwater to mix with the urine to then fertilise the tomato plants.