Wednesday, 6 April 2016

The Humanure Project : My Experiments with Human Excreta

This post will sum up My Experiments with Human Excreta (so I did this yesterday afternoon). Many people scrunch their noses or tell me that they still have a meal or two left in the day when I tell them about what I am upto. Sure, it smells bad and sure, it looks unappealing. It is gooey to touch. However, it is let out from our body and if we look at the bigger picture, excrement is the end result of a completed food consumption process.

Compost Defined: 
Composting is a process managed by humans involving the cultivation of microorganisms that degrade and transform organic material in the presence of oxygen. When properly managed, the compost becomes so heavily populated with thermophilic microorganisms that it generates heat killing the pathogens that live inside the human body at body temperature. The final product is stable, pathogen and plant seed free and can be beneficially applied to land.

Composting toilets are gaining worldwide popularity as they are not dependent on sewers and also yield a dividend - humus, which allows such a sanitation system to yield a net profit, rather than being a constant financial drain. The composition of human excreta is 65-85% water, Carbohydrates, Proteins that are converted to amino acids, Fat (less than 6%), Fibre and insoluble mineral salts.

To make compost using human excreta.

Source of Excreta:
Permission was taken from the Ahmedabad Municipal Corporation to obtain human excreta from the mobile toilets they lend out for weddings and big functions, but I ended up with 30 litres of Urine!

Therefore, the drain holes of my college were opened and excreta was removed from them albeit the fact that it was a week old.


Holes were punched (dia - 6mm) in the base of a plastic buckets and they were laid with a layer of wire mesh. Additionally, 3 holes of a smaller diameter (4.5 mm) at different levels in the bucket to insert a temperature probe.

Equipment: Dried leaves, sawdust, plastic mugs, weighing balance, buckets for layering compost and a spray bottle for moisturizing.

Layering details: from bottom to top , bracket indicates number of mugs
Sawdust (2) . Excreta (1) . S (1) . E (1) . S (1) . E (1) . S (1.5) . Total weight : 2.5 kg
Leaves (2) . Excreta (1) . L (1.5) . E (1) . L (1.5) . E (1) . L (1.5) . Total weight : 2.0 kg
Grass (2) . Excreta (1) . G (1.5) . E (1) . G (1.5) . E (1) . G (1.5) . Total weight : 2.0 kg

Moisturize. moisturize. moisturize. Since the feces and carbonaceous material - sawdust/ leaves/ grass aree dry, the pile has to be moisturized. A high level of moisture - 50 - 60% is necessary for the microorganisms to work happily. A pile prevents waterlogging, leaching and holds heat.

The feel good moment: 3 neat piles layered with human excreta and grass, sawdust and dried leaves respectively. And contrary to what you might think, it does not smell bad. I have transferred these containers from the garden to my classroom, and so far, no one is complaining!

This is being kept under observation for a month. The current temperature in Ahmedabad is 32 degree Celsius today and is set to rise to about 42 degree Celsius this month.

After conducting this experiment, I now know why people would not want to compost their own excreta so readily. There are problems such as people do not want to look at their own excreta, it smells bad because of the presence of Nitrogen , Potassium and Phosphorus (the exact components of a fertilizer) etc. In some commonly existing toilets around the world, people do not have to deal with or look at their own excreta because, after we flush, the excreta has its own journey through the huge network of drainage lines. It is out of sight, out of mind. Practicing empathy by dealing with human waste directly has given me better insights which will surely contribute in distinguishing my approach towards solving open defecation in India.

But, what if there are no drainage lines? (This is a true scenario in a majority of Indian areas)
This post is already getting long, so for more information, refer to the following

1) The Humanure Handbook - Joseph Jenkins, 3rd edition, Publisher : Joseph Jenkins Inc.
2) Compost Toilets, a practical DIY guide - Dave Derby, Publisher : Low Impact Living Initiative

Read More:
1) What happens after you flush?
2) Monitoring moisture in composting systems
3) Make a compost pile
4) Maintaining the Carbon/ Nitrogen ratio

special thanks to Uttisht Varanasi from Product Design Year 3, National Institute of Design for documenting the whole process

P.S. This post has been featured on the official blog of Ekam Eco Solutions, an IIT Delhi incubated company - Understanding Sanitation with due credit. Click here to go to the blog.