Unless you're sick or starving, you're probably on the toilet at least once a day. While sitting on the loo often provides plenty of time for contemplation, have you ever wondered what happens once you flush or why when it rains you can't swim for a few days?
Your poo ends up either in a septic tank or goes through an elaborate network of pipes, collection wells and pumping stations till it reaches a sewage treatment plant (STP). Here, it undergoes a degree of 'processing'; but one way or another, you're still left with a smelly, troublesome sludge. This sludge goes into landfill or the ocean; it leaches into groundwater, emits greenhouse gas emissions and often makes you sick. The stuff in your septic tank is often pumped out and discharged either into an STP, onto open land, or into a river or the sea.
Sh*t happens. That's just an inescapable fact of life. But with a global population of 7.6 billion and counting, can we continue to remain disinterested or resigned to an outmoded system? I don't think so.
So what can we do? For starters – plenty. For all its problems, poo can be pretty valuable if you know what you're looking for. It's rich in organic matter and packed full of mineral goodness, particularly nitrogen, potassium and phosphorus (Commonly known as NPK). These are primary nutrients that have a widespread application in agriculture. Why is this important? Agriculture accounts for 70% of all water use, 7% of all greenhouse gas emissions and 5% of all energy use, globally. These are significant numbers, but the real picture is more worrying: run-off from farms carries nutrients into local water bodies, which impacts the ecology of local systems, leading to the dying out of species. A specific case in point is the drastic reduction in the guppy population (estimated at between 70-90%) across South Asia. Guppies are a small fish endemic to lakes and streams. When nutrient-rich wastewater and run-off from farms enters these water bodies, it leads to a phenomenon called eutrophication, where you're left with algal blooms, which in turn result in an ecological 'dead zone'. These guppies and other species like frogs die out, while mosquitoes thrive. Guppies and frogs are natural biocontrols, eating mosquito larvae and adult mosquitoes, thereby keeping their populations in check. The surging numbers of vector-borne diseases like malaria, dengue and chikungunya reflect this fact.
Also consider for a moment the political implications of New Zealand's fertiliser imports, accounting for over NZD 100 million annually. Most of the phosphorus NZ uses come from Western Sahara, a politically contentious region with significant allegations of human rights abuses.
Within this context, three is an alternative: a means and method of recovering resources from poo, while simultaneously ensuring we preserve our ecology, are mindful of public health, sensitive to all other forms of life and don't destroy existing businesses and livelihoods.
To be sustainable, an approach needs to stand on three legs, like a tripod: technology, policy and finance. The technology is relatively straightforward. We utilise a process called anaerobic digestion, but we've enhanced a few steps of this process to make sure it is efficient and consistent. Our digester is like a mechanical recreation of a cow's gut, which many of you might recall from basic school biology. There are multiple chambers and phased digestion, which ensures thorough utilisation of all the organic matter, converting approximately 60% by mass from solid to gas. This gas, called biogas, contains significant energy. You can use it to make electricity, burn it to supply heat and even use it as automotive fuel (subject to further processing). Better still, you've offset those pesky greenhouse gas emissions and put that otherwise troublesome methane to good use.
What you're left with is a nutrient-rich and pathogen-free product, which makes for an excellent fertiliser. Moreover, since it is biogenic, it is more easily absorbed by crops and also requires less water, thereby leading us through a virtuous cycle.
Which leads us to our central issue policy. Everyone is aware of how NZ has signed into law something which is popularly referred to as a 'zero carbon bill', which aims to make the country a net-zero emitter by 2050. What's less well-known is how New Zealand created a Centre for Integrated Biowaste Research, or CIBR, a few years ago. CIBR's mandate has been to study the reasons and suggest solutions to NZ's sludge problem. An enabling policy environment exists.
So, what's the catch?
Cost, you say! No! Let's take Wellington as a test case, the 'coolest little capital in the world', a consistent ranker in everybody's 'best place to live in the world'. Which sadly, sends its poo to landfill mostly, but sometimes into Wellington harbour, and sometimes into Titahi Bay. A solution must be found, Council has deliberated, and an option costing up to NZD 185 million has been shortlisted. This will inevitably lead to a significant increase in fees and taxes to ratepayers. By our estimate, the solution we propose can be implemented in NZD 35 million, which is NZD 150 million LESS.
Leaving things the way they are will not make them better. We can and must do better. Indeed, scepticism and circumspection have their place, but consider aviation as an analogy. A little over a hundred years ago, it was believed that humankind could not (and should not) fly. Those dreamy-eyed engineers were ridiculed, some even excommunicated for thinking that man could fly. Today, flying is commonplace (Covid 19 aside). You can eat, sleep, watch TV, even use the loo, all the while sitting in a pressurised aluminium sausage 30,000 feet above ground travelling at eight-tenths the speed of sound.
That's something to think about next time you're sitting on the loo