To my regular readers it is well-known that I object strongly any use of so-called biodegradable or compostable packaging material. First of all no packaging material biodegrades in a landfill by lack of oxygen and the far too few industrial composting facilities often refuse to take packaging material into their processes. Furthermore, let’s face it, there is no such thing as a pure one component in packaging material. There always are coatings or additives and often more than one layer of different materials.
In my vision, there is only one answer to our increasing mountain of post-consumer packaging material. Technology has to help us to develop recycling systems, preferably the ones which recycle “cradle-to-cradle”. And more and more of these systems are coming to age, while others are under development to fill the non-covered spaces.
Today I want to discuss the, still by many people believed to be unrecyclable, and as such undesirable, packages composed with an aluminium element.
There seems to be some confusion and misconception about recycling of packages which hold elements of aluminium. In other words the pouches made from a combination of plastic/aluminium or the famous beverage cartons made from paperboard /aluminium/plastic.
It takes approximately 95% less energy to produce secondary aluminium, via recycling operations, than is otherwise consumed when producing primary aluminium from bauxite. This is one of the main reasons why recovering the aluminium component from packaging material is so important and justifies the development of sophisticated recycling systems.
Let’s start with a look at the recycling of flexible pouches, a packaging format with an immense growing potential. Pouches have many benefits such as light-weighting, leading to savings in material and transport costs, but due to the (food) content they often have an aluminium layer, and consequently are said not to be recyclable. It is obvious that brand owners are keen to see this changed, as they want to be able to put a ‘recyclable logo’ on the packaging to reinforce their sustainability credentials.
The above claim about the non-recyclability of flexible pouches with an aluminium component is correct. However recent developments might bring this condition to an end.
The Enval recycling process
Enval, a UK-based company, a spin off from the University of Cambridge, is seeking to commercialise its patented know-how that it said offers a genuine recycling route for plastic/aluminium laminate packaging that has, to date, been unrecyclable.
With recent investments secured from a syndicate of investors including Cambridge Enterprise, Cambridge Capital Group and Cambridge Angels and the backing from industrial partners, like Kraft Foods and Nestlé, Enval expects to bring its first commercial plant into service towards the middle of this year.
The feedstock would come initially from industrial waste generated throughout the packaging supply chain, from sources as varied as web laminate makers, packaging converters and even food manufacturers. The company will later look to source post-consumer waste.
Enval’s patented technology offers a genuine recycling route for plastic/aluminium laminate packaging. The technology separates the material into its constituent components, producing clean 100% aluminium ready for introduction into the secondary aluminium supply chain and hydrocarbons that can be used as fuel or chemical feedstock.
The Enval process is based on a process called microwave induced pyrolysis which allows the waste to be treated in the absence of oxygen. As opposed to incineration, pyrolysis takes place without the combustion of the material (in this case the waste) avoiding the production of green-house gases or toxic emissions. Furthermore, since the Enval process uses microwave energy as the source of heat, by using renewable or green electricity, the process can be made carbon neutral.
Recycling beverage cartons
It certainly is true that much of the paper used in beverage cartons (Tetra Pak, SIG Combibloc, Elopak etc.) is virgin fibre and is recovered at paper mills through a de-pulping process. Worldwide there are some hundred paper mills which recycle post-consumer beverage cartons, recovering the paper part of the cartons. The paper mill that recycles the most cartons is the German Papierfabrik Niederauer Mühle GmbH, recycling about 100,000 tonnes of cartons every year – the equivalent of 500 million beverage cartons.
However, this leaves a plastic/aluminium residue that isn’t and can’t be processed by the said paper mill and as such is currently disposed of to landfill or incinerated. But this is unnecessary and a waste of good quality prime aluminium.
I suspect that from this practice comes the general believe that beverage cartons can’t be recycled. Furthermore municipalities with a selective waste collection in place, forbid their inhabitants to put the beverage cartons on the same heap as paperboard, using the argument of non-recyclable.
But it has to be said we do recycle beverage cartons already for years.
In 2009 I wrote about small scale recycling of post-consumer beverage cartons and the first sophisticated recycling plant for Tetra Paks in Piracicaba / Brazil, which comes very close to the ‘cradle-to-cradle’ principal. The joint-venture between Alcoa Aluminio, Tetra Pak Brasil, Klabin and TSL Ambiental, uses ground-breaking plasma technology, which enables the total separation of aluminium and plastic components from the cartons. The plasma process allows for the return of all three components of the cartons to the productive chain as raw material. It’s not a perfect closed loop or cradle-to-cradle recycling as these three recycled components are not re-used in new Tetra Paks.
And the technology evolves. End of last year Stora Enso, inaugurated its new facility in Barcelona, being the first to employ technology called pyrolysis that enables the full recovery of plastics and aluminium used in beverage cartons.
The plastic/aluminium laminate from recovered beverage cartons is separated by the new processing technology. This means both fibre and aluminium can be fully reused and the plastic to utilised to generate energy in the mill. The recovered fibre is used for the production of white lined chipboard at the site.
The pyrolysis process, refined in partnership with Alucha Recycling Technologies, begins with the polylaminate (plastic/aluminium mixture) that has been separated from the beverage carton paper in a pulping chamber that works much like a washing machine.
This residue is dried and broken down into small pieces before being put through the pyrolysis process that involves exposing the material to 400ºC of heat in an oxygen free chamber.
The heat causes the plastic to evaporate while the aluminium stays where it is. The evaporated gas can be used to generate electricity, while the aluminium remains un-oxidised and can be recycled and re-melted without problems to be used to make new aluminium products.
The distinguishing features of the new system are that unlike a previous technology used at the plant of Corenso Varkaus in Finland that failed for economic reasons, the new pyrolysis operates at a lower temperature (400ºC versus nearly 800ºC) and operates in a zero oxygen chamber.
The chamber at Corenso Varkaus had 10-15% oxygen and this created aluminium oxide which is worth much less than pure aluminium.
The process generates valuable aluminium and enough power, via the evaporated plastic, to provide for 10% of the energy requirements at the Barcelona paper mill. And lower temperatures mean this can be achieved with a lower energy bill.
With the help and technical assistance of Tetra Pak, Stora Enso began operating the pyrolysis process this summer after having already run a pilot with an annual capacity of 1,000 tonnes of beverage carton. The newly installed machinery will allow Stora Enso to move up to industrial scale production this year, with a capacity to process 30,000 tonnes of used beverage cartons annually.
Stora Enso states that the Barcelona mill now receives used milk and juice cartons from Spain, France, Portugal and the UK.
We have seen that in both processes, The Enval technology for flexible pouches and the Stora Enso plant in Barcelona for beverage cartons, pyrolysis lies at the heart of both processes. Now there is one interesting thing as at the heart of both companies, Enval in the UK and Alucha in Barcelona, which refined the technology for Stora Enso, sits Dr. Carlos Ludlow-Palafox, the technologist responsible for the pyrolysis technology. Carlos Ludlow-Palafox graduated with a degree in Chemical Engineering from the Universidad Iberoamericana in Mexico City in 1996. He gained a PhD with distinction in pyrolysis technology from the Cambridge University, where he, as a Post-Doctoral Research Associate, in conjunction with Professor Howard Chase, conducted research into the microwave pyrolysis of plastics and plastic-containing wastes in batch systems. He is connected to both up-starts.
Concluding we can say that the aluminium component in all different packages. from pouches to cartons, can now be recuperated and used as new in the next generation of packages. Now it is up to the Councils to implement a selective collecting system for post-consumer pouches and cartons.