This is beyond the recycling of household waste – although we will start with that. Green industrialists aim to develop an industrial ecosystem, where the waste from one industry produces ‘food’ for the next. This is called an Industrial Ecology and analyses material flows through industry from mining and harvesting hopefully into a continually repeatable loop.
On this page:
- Will Gasification convert much of our waste into jet fuel?
- Household waste today
- Local recycling businesses collect metals and e-waste
- Plastics – Catalytic Hydrothermal Reactor
- Plastics – Warm bacterial reactors
- Green Chemistry trying to get alternative feedstocks to fossil fuels and use less toxic stuff where possible
- Fairer industry for the poor – open source hardware lets local workshops can build hardware 1/8th the cost of name brands!
1. Will Gasification convert much of our waste into jet fuel?
Gasification has the potential – still not thoroughly demonstrated and commercialised – to take truly vast quantities of household waste and turn it into useful products such as jet fuel and building materials.
So as I describe more niche applications for recovering and recycling our waste below, please keep in mind that the moment I heard Gasification had become viable, I would support it completely taking over processing Municipal Solid Waste. After all, there are 2 billion tons of the stuff worldwide. Imagine that going into airline fuel and other useful fuel and petrochemical and building products? Or maybe that will not be economical – and Gasification will process some categories of waste and others will be processed in the methods below. It’s a big world. As long as the waste is used as a resource somewhere in the industrial ecology – I’m happy.
See my Gasification page for more.
2. Household waste: how many Australian suburbs recycle
Many Australian suburbs have 3 bins they use. Recycling schemes can get out of hand for users – but this is how we do it here. It’s a start – but I hope it improves. I don’t want it to get too cumbersome. The Japanese require you to sort every tiny specific thing into dozens of different plastic bags which must be put out on 4 different days of the week every week! Neighbours have even been known to return your incorrectly sorted plastic bag to your house. All of this fuss and bother is just not needed. Two bins go out together each week – Red bin every week, and the other two alternate. Done.
RED bin for all non-recyclable household waste, such as dirty diapers, pizza boxes, old shoes, etc.
GREEN bin for lawn clippings and yard waste and even kitchen peelings and restaurant scraps. Maybe one day future pizza boxes can be more biodegradable and go in there? It will all be composted down into soil.
YELLOW bin to recycle paper, glass, PET plastics and aluminium cans. Sadly non-PET plastics – about half of them – cannot be recycled yet in Australia and many countries. They go to landfill. More on that under plastics below.
must go in the red bin. (I hope this changes as researchers work on enzymes that can recycle ALL plastics – as the PET system is technically not recycling indefinitely – but down-cycling.)
Our council also has a recycling drop-off point if you can be bothered driving all that way! A great environmental service might be volunteers organising a monthly truck to take a bunch of stuff to your local council recycling area.
3. Local Recycling businesses are collecting more
Metal: Our local shops have a community bin for a metal recycling company. Someone in a store just calls them when it’s full, and they come and get it. I recently had an old metal BBQ I broke down and drove into this company. It felt good knowing it was going to be recycled.
Ewaste: Once every few months our community will book Arnie’s Recall – a local e-waste recycling bin that try to save and sell old radios and electronics – or if it’s truly broken break it down and sell parts and then recycle the rest for you.
4. Plastics – Catalytic Hydrothermal Reactor
Many countries have the PET plastics recycling scheme which, while a good early start, is not complete. It actually downcycles the quality of plastic. If you imagine plastic molecules as a Lego tower, PET smashes the Lego tower apart with a sledgehammer. Some of the bits break rather than separate. But the technologies below are gentler and attempt to separate apart those molecules. It all sounds like Gasification mentioned above – but more specifically tailored to plastics and wood in particular.
First, there’s Australia’s Licella – which is being built in the UK first. As the ABC reported in 2019:-
“Now Dr Humphreys sees the mountains of stockpiled plastic as a wasted resource — one he says could be used instead as fuel or remade into new plastic.
His Catalytic Hydrothermal Reactor (Cat-HTR) does just that through a form of chemical recycling that changes the plastics at a molecular level using hot water at a high pressure to turn them back into oil.
“What we’re doing is we’re simply taking those materials and converting them back to the liquids and the chemicals they came from,” he told 7.30.
From there, the oil can be turned into bitumen, petrol or back into different kinds of plastics.
Dr Humphreys said the Cat-HTR technology he and his co-founder patented was different from existing plastic-to-oil technologies like pyrolysis, which is a process that involves heating materials at a very high temperature.
Unlike traditional physical recycling, it does not require plastics to be separated according to type and colour, and can recycle anything from milk cartons to wetsuits and even wood by-products.
It also means plastic products can be recycled again and again.
After trialling the technology for the past decade at a pilot plant on the NSW central coast, the company Licella is now ready to take its idea to market.
It is opening its first commercial recycling plant in the United Kingdom, where it says the government grants and policy environment are much more favourable than in Australia.”
5. Plastics – Warm bacterial reactors
Another approach is to find bacteria that eat plastics, and keep them nice and cosy in a warm bio-reactor. The Guardian February 2022:-
Meanwhile there is evidence that microbes all around the world are evolving similar abilities. A study published in October 2021 looked at microbial DNA from a range of habitats. In areas with high levels of plastic pollution, the researchers found that the microbes were more likely to have enzymes with plastic-degrading tendencies. In line with this, a 2020 study identified a soil bacterium that can feed on some of the components of polyurethane, which releases toxic chemicals when it breaks down.
The question now becomes: how significant a role can these enzymes really play in reducing plastic pollution?
The circular economy
So far, most of the activity has been in universities, but some groups are attempting to commercialise the technology. The University of Portsmouth has set up Revolution Plastics, which aims to forge links between academics and industry. “We’ve already advertised a joint PhD project with Coca-Cola,” says McGeehan. He is also part of an international research team called BOTTLE, which is negotiating with large companies.
The most advanced project is run by Carbios, a French biotechnology company. In September 2021 it opened a pilot plant in Clermont-Ferrand, where it will test a system for recycling PET. Carbios’s system uses an enzyme that was first identified in compost, which they modified so that it worked faster and could operate at high temperatures where PET is softer.
The advantage of these enzymes is that they break down the plastic at the molecular level, so it is possible to recreate the highest-quality plastic. In contrast, other forms of recycling cause a slow decline in quality, until eventually the plastic cannot be recycled again and gets landfilled or incinerated. Enzymatic recycling, in theory at least, is truly circular. “That’s what we call a closed-loop recycling system,” says Ramos. “You recycle something, but then you’re able to make something new of the same quality out of that.” To date, only a tiny percentage of plastics are being recycled in this way, but the enzymes could change that – “Which would be great.”
McGeehan says: “I think in the next five years we’re going to be seeing demonstration plants all over the place.”
Still, there are limits to the enzymes’ usefulness. “It will never be a one-size-fits-all type of solution,” says Ramos, and we should not count on the enzymes to mop up all our plastic waste. Some plastics are even tougher than PET.
Blank points out that the enzymes work best if the plastic has been softened by heating. That means releasing the enzymes into the environment would not do much good: they only really work in temperature-controlled reactors. So the solution to plastic in the sea remains the same as before: we have to stop releasing it in the first place.
Nevertheless, it seems likely that plastic-eating enzymes will have a role to play as societies move towards a circular economy in which everything is recycled as much as possible. In a study published in July 2021, McGeehan and his colleagues estimated how much enzymatic recycling of PET will cost. They calculate that it could compete on cost with standard manufacturing methods, which use fossil fuels as feedstock.
The key is to be savvy about where we use the enzymes, says Blank. Some plastics can be mechanically recycled, a technology that is improving rapidly, so they probably are not the best targets. Instead, he says, researchers should go for plastics that cannot be recycled any other way – particularly if they can become substances that are otherwise expensive to make.
Ultimately, the enzymes have to be part of a revolution in the entire way we make and use plastics, says Ramos. Better methods of recycling are useful, she adds, but they are only part of the solution. It is also important for plastic products to be designed in such a way that they can easily be reused and recycled. That might mean avoiding designs that use several kinds of plastic, or fuse plastic with other materials, as these are very difficult to recycle.
6. Green Chemistry trying to get alternative feedstocks to fossil fuels and use less toxic stuff where possible
Some researchers are developing alternative plastics that don’t use petrochemicals, some associations are prioritizing green within their members, whole green-chem institutes are being founded, and groups are trying to teach chemists to green their processes.
Green chemistry, also called sustainable chemistry, is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances. Whereas environmental chemistry is the chemistry of the natural environment, and of pollutant chemicals in nature, green chemistry seeks to reduce and prevent pollution at its source. In 1990 the Pollution Prevention Act was passed in the United States. This act helped create a modus operandi for dealing with pollution in an original and innovative way. It aims to avoid problems before they happen.
via Green chemistry – Wikipedia, the free encyclopedia.
7. Fairer industry for the poor – open source hardware lets local workshops can build hardware 1/8th the cost of name brands!
It’s open sourced industry for the poor. If developing nations get a hold of this philosophy, they’ll be able to order parts online, build the equipment themselves, save a ton of money – and repair it themselves locally. The possibilities are amazing!