I’ve noticed in the past how, when I am thinking about some topic, I am much more likely to notice things related to that topic, and so it was with recycling human waste. The past couple of weeks see me flushed with material.
“Peecycling” is too good not to steal
Peecycling — the word, not the concept — was new to me when I came across it in a press release from the University of Michigan: ‘Peecycling’ payoff: Urine diversion shows multiple environmental benefits when used at city scale.
The concept had been a delightful morning ritual back in the day, when I regularly climbed a little ladder to increase the nitrogen content of my compost heap. As for the word, this particular release details research that makes big claims. Reducing the need to process wastewater and to make and transport synthetic fertilisers, along with the benefits of avoiding the effects of pollution, such as algal blooms in lakes, far outweighs the cost of collecting the urine, processing it and transporting the resulting fertiliser.
Wastewater — the fact that we use perfectly good water to carry away our excreta — is a big part of the problem for urine, because it dilutes the nutrients to the point where removing them from the waste stream becomes prohibitively expensive. As a result, where they exist, treatment plants generally aim to get chemicals below mandated levels and discharge the rest, to cause algal blooms.
So it is good news that this life-cycle analysis from the University of Michigan calculates that under some circumstances, wastewater treatment could be done away with, but with a caveat. It is very much a hypothetical, or scoping, study, looking at various elements in the recycling loop and doing the sums. It did involve installing some experimental urine-diverting toilets on campus and building a lab-scale plant to convert the urine to fertiliser, but basically, it is a proof of principle. Still, a principle that could be acted on.
Peecycling brought up to date
Some of the data used in the University of Michigan models came from the Rich Earth Institute in Vermont, which has been researching urine into fertiliser since 2011. It was the subject of the earliest use I could find online of the word peecycling, (although New Scientist used “pee-cycling” in what I guess might have been the Christmas Issue, 2006). As I said, though, there’s nothing new about the concept. The Rich Earth Institute has modernised it somewhat, with centralised collection, close partnerships with local farmers and some research. What is new more widely is the technical approach, which goes well beyond peeing on the compost heap.
Some of that is of little concern. A pan-European consortium of researchers, working with the European Space Agency, has been testing urine as a material for making concrete on the moon. Japanese scientists would probably say it would be more useful for fertilising lunar food. Neither takes my breath away.
What about the water?
One downside of recycling urine at any distance from the source is that most of what you are trucking is water. According to studies in Sweden, 15000 kg of urine contains 400 kg of fertiliser. How much more sensible, then, to get rid of the water. This the Swedish research has done, using an alkali to prevent the unwanted breakdown of nutrients that is responsible for the smell of stale pee.
Any water in the now alkaline urine is evaporated and only the nutrients are left behind. We can even condense the evaporated water and reuse it for flushing toilets or washing hands.
The process does require a toilet capable of diverting urine for special treatment, but according to the researchers, the process is simple enough to do it yourself. The company spun off to commercialise the research is leading a project to pilot the process in Durban, South Africa, which, I learned, is a global leader in urine-diverting toilets.
Let’s talk about pig poop
Poop has been much less prominent in the news lately, at least as far as human poop is concerned. Maybe that’s because it is actually far less useful as a fertiliser than pee. Nevertheless, getting rid of it can be a problem, not least when thousands of animals are crammed into a small area.
Recycling animal manure has become more and more difficult as the animals that excrete it have moved further and further from the fields that feed them. I remember visiting one of the few remaining mixed farmers in Ohio, who supplied pigs for Spam. He told me with glee that some his neighbours would pay him to remove the manure their pigs produced, giving him cash in hand and saving him having to spend as much to fertilise his corn and soybeans. Alas, for the truly huge hog operations, like those in coastal North Carolina, that’s not an option.
So I’m not really sure what to make of strong objections to a plan to turn North Carolina’s pig manure into biogas.
Right now, eastern North Carolina suffers around 4000 lagoons full to the brim of pig effluent. It’s a disaster for residents, who have long fought against the environmental racism it represents, and even worse when storms breach the fragile lagoon walls and floods allow the effluent to run into the countryside. So I’d have thought that a $500 million project to collect the effluent through a network of pipes and turn it into biogas would be welcomed. But apparently not. According to The Guardian, loud objections to the scheme come from “environmental activists who see it as seeking to profit from an ecological problem rather than fix it”.
There is, of course, no fixing the problem, not as long as you’ve got 9 million closely-confined hogs producing 10 billion gallons of waste a year. You can only “fix” that problem by re-integrating pigs onto mixed farms, and that’s simply never going to happen. I guess I’m naive to think that finding value in the waste product that makes it worth dealing with actually is a fix, of sorts.
One of the activists clearly thinks so:
“They’re not treating the waste, they’re converting it, so how is that hog waste ever clean?”
“It only lines their pockets. They’re trying to sell it as renewable energy. It’s only renewable if pigs continue to poop, which is why I’m afraid they’re going to push the moratorium on new hog farms, because if you have that great of a demand, you have to supply to meet it.”
More pig poop
No mention of how Muyuan Foods plans to deal with the waste from the world’s largest pig-raising property, which opened its doors in September. Reuters reported that the giant factory, near Nanyang,
“will eventually house 84,000 sows and their offspring, is by far the largest in the world, roughly 10 times the size of a typical breeding facility in the United States. It aims to produce around 2.1 million pigs a year.”
Seriously, not one word about waste. Lots of guff about robot pig handlers, temperature sensors to monitor for disease, the economic threat to other pig producers, sterilised feed, etc etc etc. But about the billions of gallons of effluent, not a word.
I guess the Chinese have simply chosen to forget their proud history of waste recycling.
A shower of opportunity
If you listened to last week’s episode, you’ll remember the story of the Chinese entrepreneur who built a comfy facility, complete with toilet paper, for the free use of travellers on the road through his town. Win-win.
And perhaps you’ve heard about the traffic jams of trucks on both sides of the Channel. Thousands of drivers with nowhere to go, in both senses of the word. I understand the UK government is thinking of installing portaloos. The Farage Garage alone holds 1700 trucks. At a minimum, then, 1700 adults, producing anywhere between 400 and 2000 ml of urine each a day, say 1200 ml. That’s easily 2000 litres which, if the Swedes are right, is about 50 kg of fertiliser a day.
Just what the Garden of England needs.
- Making synthetic fertilisers “is responsible for 1.2% of world energy use and associated greenhouse gas emissions”. Or maybe “2% of the world’s energy”.
- Urine makes up less than 1% of the total volume of wastewater, but “contains 80% of the nitrogen and 50% of the phosphorus”.
- “If implemented worldwide, recycled urine could replace nearly a quarter of all the synthetic nitrogen fertiliser used in agriculture.”
- “Transporting about 0.45 kg from the Earth to space costs about $10,000.”
- In 1970, the average farm in North Carolina raised 60 pigs at a time. Today, the average is 4000 animals per operation.
Take care, and stay safe.
p.s. The photo explains why, unlike Reuters, I call Muyuan Foods’ monster a pig-raising property, rather than a “mega-farm”. Drone photo by Muyuan Foods/Handout via Reuters