Turning human manure into profitable business

So, I am working with two colleagues, writing simple guidelines for folks who want to fix their rivers. We are in discussion about exactly what needs to be included, where to place it and how to write it. We get to the heading “water quality”. Silence. We all look at each other for a while. “Coffee time!”

How do we write a guideline for fixing water quality in SA rivers in 2023.  Anyone? Imagine the text:  “If you have water quality problems in your river or estuary, you really need to fix these first, or all other interventions may be a waste of time. Your problems are likely due to sewage spills, litter, agricultural runoff, or chemical waste.”

In our experience, it is possible to deal with all but the first two. Sewage continues to flow into our waterways, both inside and outside of load-shedding. Countrywide, no court rulings against municipalities have resulted in the problem being addressed convincingly. Municipalities are generally understaffed and don’t have the budgets, skill-sets, procurement processes or the will that it takes to implement these court rulings anyway. So — sorry dear River Fixer, we can give you lots of ideas, but we can’t promise any will work. The End.

It is simply easier to drink coffee and chat.

But it’s bothersome. It keeps us awake at night. What simple piece of the puzzle are we missing? There has to be a way to manage this monster that is smothering the life in our rivers, estuaries and oceans.

If there were political will ...or ... if there was money to be made from a solution, the problem would have a short lifespan. It’s 2023! We have tech! We have alternative energy! We have genius scientists and engineers! We have bots called Siri, Alexa and Chat GPT!

In all the pondering, I discover a unicorn. 

It is in a 2019 presentation entitled Creating the world’s first sanitation unicorn by Dhesigen Naidoo of the SA Water Research Commission.

A unicorn is a start-up or business worth at least R19.5bn (US$1bn). Sorry unicorns. 

This as-yet-unborn sanitation unicorn is lurking opportunistically in a pile of brown whiffy stuff.

Yes, your own poop.

Naidoo is proposing that business take heed of the opportunity of converting human solid waste to biogas and bio-fertiliser, and extracting other micro constituents (proteins and enzymes) from it. There is massive economic and social value to be realised.

The world this magical creature will be born into is the one in which two billion people do not have access to safe water, and 3.6-billion do not have access to sanitation, according to the March 2023 UN world water development report.

“Let’s acknowledge our global service, health and service deficits! And the lost business and economic opportunity!” urges Naidoo in his presentation. His model is one of a new circular economy, with waste as its nucleus, rippling outwards to include a whole new paradigm of energy and water. Known as the alchemy of waste, this new mindset is like finding gold in waste.

The business opportunity would likely start at the level of the household and ultimately scale up to a mass market — much like solar power has in the past decade. There is a bit of perception management needed in the meantime. We have been taught to perceive our excreta as waste that we (the entitled “we”) get to flush away and forget. Off it floats. We hardly see it as a golden opportunity.

But, er, hang on. Is anyone local actually doing bio fertiliser or bio gas? As it transpires, yes. Jocelyn and Ed Gilfillan have rented Heartwood Homestead near East London. It was established in 2019 by owners Roger and Karen Galloway, specifically as an experiment in self-sufficient off-grid living. I was blown away by a presentation given by Roger in 2022.

I visit Heartwood and get a warm welcome from Jocelyn and Ed. We chat about the bio-loo. What a conversation starter! The loo is a surprise to me, because people have conditioned ideas of an outhouse, long drop situation — whereas this loo is very much inside the house.

Cool, white and breezy, white-framed windows, and no odour at all. On the lid is a sticker “Please close the lid after you have done your business, not before or during. That could be messy”. And behind it a poster: “We really need to make people understand how stupid it is to poop in clean water.”

There are two bench-style loos in the room, one on either side. The lid of one is closed, with a pot plant on top of it, as what lies beneath is busy digesting at the moment.  The other is a normal-looking loo top,  but with a long, vertical, cylindrical chute under the seat.

This leads into one of two brick chambers. The floor of this room is the ceiling of the chamber. So the plan is: you do your thing, use toilet paper and throw it in. If you have pooped, you cover it with a cupful of sawdust (stored in a drawer at arm’s length), shut the lid, and you are done. No water used, except to wash your hands.   

Jocelyn and Ed show me Roger’s graphs which indicate a potential water saving of 157,680l a year for a family of six, and 105,000l for a family of four. That’s significant.  And nothing floats away out of sight to be “wasted” or to cause death to our rivers. It is busy digesting for a better purpose. Ed quotes Roger on the issue of the insanity of waterborne sewage: “You are taking two valuable products (poop and clean water) and mixing them, to create a toxin!”

And where do the wood shavings come from? That is a by-product of timber factories and furniture production, says Ed. So we will not need to cut down indigenous trees to supply it.

Jocelyn, who grew up in Joeys, says that after only a month of living at Heartwood is she used to the idea of a composting loo, and using it. There a little issue, it seems. Jocelyn says any light odour is quickly dealt with by addition of lime or a naturally fermented liquid similar to a milk product.

Once the solids have been adequately digested (around a year), one breaks down the rough-built bricks to reveal the access port on the chamber outside of the house. And inside is the bio-fertiliser ready to use as plant food. Remove it and rebuild the wall. I do remember Roger’s photos of his lovely rich, dark and apparently odourless ‘humanure’.   

Our conversation is also rich and colourful, and a story in itself. I am inspired by this couple and their dedication to trying a self-sufficient, local-based lifestyle while both working full time. “The idea is to keep the nutrients at home,” says Jocelyn. They also run a self-catering Air BnB in a separate double-storey cottage at the end of a forest path, and yes, it also has two spotless, white, odourless bio-loos. 

In the Heartwood loos, the gases generated by the decomposition process are vented through two flues on the outside of the house. Adding in the biogas production would be the next step to realising the value of our human by-products. 

When producing biogas, separated solids must undergo an anaerobic (oxygen-free) digestion process, which generates a gas mix of about 75% methane, 25% carbon dioxide, and traces of other gases and water. There are many different designs for the biogas digester, but in general, it is designed such that the gas that is generated can be tapped off from the anaerobic chamber via a tube or pipe which leads directly to the cooking equipment.

In principal, biogas can be used like other fuel gas. At household level it is suited to cooking or lighting, hence the interest in biogas as an energy source for poorer countries. At a larger scale, production of biogas in large anaerobic digesters would allow one to generate electricity. 

Rough estimates on the web are: 1kg of poop would generate about 50l of biogas,1kg of cattle dung would produce 40l of biogas, and 1kg of chicken droppings, about 70l of biogas. The gas consumption for cooking per person and per meal is between 150 and 300l of biogas, and about 30-40l of biogas would be needed to boil a litre of water. So there you have it. 

As Naidoo put it, every human produces up to 450g of poop a day, and we are seven plus billion on Earth. So our global annual poop pile would amass 2.9m metric tons a year. It is unlikely we are going to plunder that resource. 

So, if we want to rid ourselves of the sewage issue, clean up our rivers and oceans, have more available drinking water (think: Gqeberha), cheap compost, and possibly even free domestic gas, perhaps it’s time to rethink flushing away our gold.  Some clever folks are going to birth a unicorn along the way. And then perhaps we can write that guideline!

Mandy Uys runs Laughing Waters, an aquatic ecosystems science consultancy in East London, specialising in freshwater ecosystem assessment, conservation and restoration. — DispatchLIVE