Fantastic Faeces and How to Utilise Them.

For this week’s Science Saturday our science correspondent Charlie Keeble has gone down the u-bend to see how human waste can make a valuable resource to ecology. This story is quite literally a story about mess and how it can save our food supply and plants. In the science fiction film The Martian astronaut Mark Watney is stranded on Mars and has to use his skills as a botanist to survive in a human habitation module. Watney’s scientific training in growing food was valuable to his survival because he needed to grow most of his food in the Martian soil. However, the soil of Mars is completely infertile and the conditions for growing food are non-existent. So he cultivated the soil into the habitat base for farming potatoes and fertilised it using his own faeces.

Astronaut Mark Watney in ‘The Martian’ harvested potatoes in faecal fertilised soil for survival. This is one of the best scenes of survival strategy I’ve seen in a space film and is one of the most scientifically accurate plot devices. In fact, using poo to fertilise soil is widely used on farming methods in agriculture to make produce germinate and grow until it’s picked for the harvest. The soil that our food is grown in has got the elements of poo that allow plants and vegetables to bloom.

So what is it about faeces that makes it such a useful organic substance for soil fertility? Human and animal faeces are composed of nitrogen and phosphorus, which are essential compounds for the fertility of soil. They are also used in artificial fertilisers as well but here when the poo is mixed with the soil it becomes enriched with nutrients. Additionally, organic matter in the soil provides energy and carbon for soil organisms, and the decomposition of this matter releases beneficial vitamins and amino acids. When water and sunlight is added it generates photosynthesis and hence the plant matter grows in the soil.

Nitrogen and phosphorous along with 16 other micronutrients and macronutrients are essential for plant growth. In the case of nitrogen, it is exchanged between the soil, air, and water in a reaction process known as nitrogen-fixing. This involves breaking atmospheric nitrogen (where it’s in the form of dinitrogen) apart into biologically active nitrogen compounds for the process of plant development and growth. The nitrogen fixation is achieved by one of two naturally occurring ways involving oxygen from lightning strikes producing nitrates (NO₃^–) or hydrogen from interacting with water producing ammonium (NH₄⁺).

Once the nitrogen is inside the plants it converts to amino acids, the essential building blocks for proteins. These amino acids are utilized in processing enzymes and structural parts of the plant and can become part of the stored proteins in the grain. Nitrogen is also responsible for the dark green colour of the leaves of various crops, as a result of high concentrations of chlorophyll. Chlorophyll is associated with the production of simple sugars from carbon, hydrogen, and oxygen. These sugars and their conversion products stimulate plant growth and development.

When nitrogen and chlorophyll are combined they utilize the sunlight as an energy source to carry out essential plant functions including nutrient uptake.   Phosphorus on the other hand has an important role in the production of plants that are food sources like fruits and vegetables. Phosphorus is a major nutrient and along with nitrogen and potassium, it plays a key role in photosynthesis whereby it metabolises sugars, energy storage, and transfer of that energy to the plant for whatever its usage is. Phosphorus also provides soil quality by promoting root growth and germination, it speeds up ground cover for protection from erosion, enhances the quality of the crops, and is vital to seed formation.

Phosphorus also works together with the other nutrients by improving their efficiency, increasing the plant’s water usage, contributes to disease resistance in some plants, helps plants cope with cold temperatures depending on the climatic conditions, and hastens plant maturity and protects the environment in order to control and regulate it’s growth rate. When phosphorus is dissolved in soil water the plant roots acquire this precious element and it is internally cycled through the soil and organic matter as part of a terrestrial survival mechanism. According to the farming industry and botany community phosphorus is in short supply and due to soaring natural gas prices nitrogen fertilisers are currently waning.

Farmers and botanists have been encouraged to uptake and increase the cycle of these elements into their ecosystems. One way they do that is making animal faeces into fertiliser to use their nitrogen and phosphorus content as a resource instead of a waste. This is called ecological sanitation. Now ecological sanitation can be a useful social invention to dealing with one major urban problem.

One of the worst environmental issues that I find from walking around Havering’s public parks and streets is seeing dog poo littered and smeared in places. But I think that mess can be made to work for us and our local park’s ecological demands that the council can act on.

Instead of relying on people putting it in bins, create latrines with removable slabs for dogs to do their business. Then take that waste and process it to create locally produced fertiliser. In some rural parts of Africa such as Ethiopia households have these temporary latrines called Arborloos. People use these toilets to poo into and then once it’s filled they use their waste as an organic fertiliser. They remove the latrine’s structure while leaving the faeces in the ground, covering it with a layer of soil, leaves and ash and then plant a tree to grow in the compost. It’s a brilliant way to make free fertiliser out of an inventive sanitation solution.

This process can be adapted in public parks where temporary latrines can be built around the park, have the dogs dump their organic waste, and then once filled use them as plots to grow trees. It can also be extended to the streets as a scheme whereby council workers and members of the public pick up and clean the streets of animal faeces. After which it can be taken to a processing facility to make lots of cheap fertiliser that can be used wherever it would be needed to increase the fertility of the soil across the borough. It could be used to help with the growing of fruit trees in public gardens to provide fresh produce for local people. This would be a practical social invention in a cost-of-living crisis.

On the subject of sanitation, I have come to realise that the amount of water that is used to flush our waste down the toilets has shown that the toilet, as a sanitary household invention, is outdated and deserves to be upgraded. This piece of technology has been around since the Victorian times and I think that utility devices like the toilet should be redesigned for ecological sanitation. This is for them to be clever contraptions that can work for the environment instead of polluting it.

One idea that I favour very much is waterless toilets that can remove harmful byproducts from human waste. Waterless toilets are already utilised and they have an advantage to infrastructure projects because they don’t require extensive plumbing systems. You can build them in remote areas where there is no utilities that would suffer from faecal diseases. Microsoft founder and philanthropist Bill Gates has contributed millions of dollars towards the development of waterless toilets, especially to developing countries where water is scarce. He did this to provide off-grid toilets to over two billion people in the world who don’t have access to clean sanitation.

One of the most recent toilet designs Gates sponsored can turn human waste into fertiliser. It works like a home based chemical processing plant in your bathroom. Such technology like this can make a big impact on sanitation since the Victorian sewers were developed to stop cities from drowning in their own stink and pathogenic filth. Intelligent toilet designs like this are widely used in the science sector such as the space industry. On the International Space Station astronauts have a toilet that takes their urine and converts it into drinking to prolong their water supplies.

At the moment the current varieties of waterless toilets that are available to buy are too expensive for most domestic households. One online shop called WooWoo shows they retail from £800 – £4000. So if the waterless toilet is to become successful in improving sanitation then the cost of a single unit will have to be brought down. This will provide the agricultural sector with cheap and reliable fertilisers that can support their industry and bring human waste as a valuable resource that can save the botany and food supply that we depend on.         

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