England (and indeed the rest of the UK) may be a green and pleasant land, but for the most part it isn’t a sylvan green, but a grassy one. In fact, just 12 per cent of the UK’s land base is forested. This means that virgin sources for paper are rare here and we must make paper from other paper.

Indeed, recovered paper is by far the most important material for the UK paper and board industry, representing 73 per cent of feedstock in 2009, according the Confederation of Paper Industries. There’s no doubt about it: paper recycling is big business in the UK. But how is it done?

Well, there are more than 60 grades of recovered paper recognised in Europe and the recycling process will vary slightly depending on what goes in and what comes out. The basic principles are the same, though, so let’s focus on newsprint. Whether we pick up a broadsheet, tabloid or local rag, this is a nation of newspaper readers: as of August 2010, Brits were consuming on average 1.39 billion newspapers a week (from 22 national titles and 1,290 regional papers). Around 80 per cent of the fibres that make up the newsprint are recycled, so it’s fair to say that newspaper recycling is a vital operation. The UK currently has three of its own recycled newsprint manufacturers – UPM Shotton in North Wales, Aylesford Newsprint in Kent and Palm Paper in Norfolk.

Though newspapers and periodicals and magazines (news and PAMs) are the meat and bones of the recycled newsprint industry, other types of materials – such as catalogues, junk mail, directories, or white office paper – can also be used. The paper comes from a variety of sources: paper merchants; publishers (who supply pre-consumer, over-issue material that never made it off the shelf); or local authority collections, either from bring banks or the kerbside.

Of utmost importance is the quality of the feedstock, which is one of the main reasons parts of the paper industry so vociferously support source-segregation. Though contamination of any kind is, of course, undesirable, glass is probably the biggest bane. Andrew Perkins, Recycling Manager at Aylesford Newsprint, explains: “If the bottle would stay whole, then it would be filtered out very easily, but it doesn’t. Very often, it’s collected in compaction vehicles where everything gets crushed together, so you get crushed glass ground into the paper. It’s very, very hard for a sorting plant to then lift that off, particularly as the bottle probably contained a sticky liquid, which glues the crushed glass onto the paper. It then comes to the mill and goes through our process. We’re using very, very fine filters to discriminate between various fibre lengths, and so you’re constantly blasting those with glass fragments. It wears away those filters very quickly.” And those filters, unlike conveyor belts, are expensive to replace.

Though Aylesford accepts paper from a few materials recovery facilities (MRFs), he notes: “The number of good sorting plants that produce a useable quality of paper is pretty minimal at the moment.” This is the main reason why fellow paper recycler, UPM has installed a full-scale (270,000 tonne-a-year) multi-material MRF at the front end of its Shotton paper mill (see news story on p4), a step that allows UPM to ensure high-quality paper is available, even from commingled collections.

Having secured an adequate quality of paper, the feedstock is loaded into a pulper. “There’s two basic methods of pulping”, explains Perkins. “In batch pulping, the vats stir up the paper and pump pulp out. With a drum pulper, it’s a continuous flow process. The pulper rotates, it mixes paper with water, breaks it into a water-fibre solution, or stock. That is then pumped out much like water’s pumped out from the inside of a washing machine, but when you pump the water out in this case, you’re taking all the fibre with it. And anything that doesn’t pulp up, like cans or plastics that have come in by mistake, continues to tumble to the very end of the drum pulper.” Chemicals, heating and the rotating of the solution, again, as in a washing machine, can also help to break the fibres down.

After pulping comes the ‘deinking’ stage during which, as the name suggests, ink is removed, along with glue residues and adhesives (collectively known as ‘stickies’). Ink and stickies are predominantly removed through a process known as ‘flotation’: the stock is placed in a vat into which compressed air and chemicals, or surfactants, are injected. Surfactants act like detergents to dislodge the ink and stickies from the paper fibres; these then adhere to the soapy bubbles and float to the top of the vat as a black frothy scum, which can be skimmed off. The sludge that results also contains fillers like clay (used to make magazines glossy) and paper fibres that have become too short to recycle (the average fibre can be recycled four to seven times). Of course, the process has to be completed many times before only paper fibres are left; UPM’s Recovered Paper Sourcing Manager, Mike Burgess, says: “This is done over and over again, and everything is loops within loops”, and Perkins says that at Aylesford, the paper is sent for physical ‘roughing up’ halfway through the deinking process to dislodge ink particles that are clinging tightly to the paper fibres.

The aim is to achieve a bright white stock (which sometimes requires a bit of bleach, such as hydrogen peroxide), which is then beaten to make the fibres swell, and paper making proper can begin. Perkins goes into detail: “We’re introducing the stock onto the paper machine at 99.4 per cent moisture, so you’ve got a very thin film of fibre being sprayed onto the machine. And that’s immediately trapped between two belts because it’s got no strength itself at this point. The way that the fabric mesh is made helps determine the formation of the paper; you’re trying to get the fibres to lie across each other as evenly as possible to enhance the strength and make sure you’re not leaving any holes. Nowadays, these belts are a plastic mesh that has plenty of holes in it to allow water to pour out of it. Also, you pass that fibre belt sandwich over a vacuum, so that more water is drawn out. Then, we put that fibre belt sandwich through heavy rollers that press the two belts together, squeezing more water out. As the fibres are pressed together, they start making a physical bond with each other.

“Then, the fibre belt sandwich goes to the drying section where the paper is passed over steam-filled rollers that are hot, and as you go down the machine, the rollers get hotter. The action of the heat on the paper drives off the rest of the water, so we get down to about nine per cent moisture content.” Moisture content varies from plant to plant – UPM aims for 10 per cent – but it’s important that it’s not too dry, which would make it brittle, and not too wet, which would compromise its strength.

Paper machines make paper at astonishing speeds – the fastest ever recorded, in Lontar Papyrus in Indonesia, went at nearly 80 miles per hour (mph), and machines at both Aylesford and UPM operate at around 60 mph. These vast quantities of paper (Aylesford and Palm Paper both make 400,000 tonnes of newsprint a year while UPM makes 500,000) are rolled onto large spools (a jumbo reel at UPM consists of 30 tonnes of paper), before being cut into smaller reels suitable for customers. And these customers then make it into newspapers for the public, and the cycle begins again…