Myth-takes – “You can sort it all with machines”

Not long ago, The Spectator gave over a page to decry the plight of poor Mrs Ware, the “frail, elderly mother” of the article’s author, Michael. Mrs Ware, he wrote:

“has recently moved in with us in Epsom and in so doing has joined the 15 million people worldwide who spend their days sorting through rubbish. Mum, however, does not get paid $1 a day. She does it for nothing. This is because we now have five separate bins and every morning she and the other 10,000-plus members of Surrey’s army of housewives sort through their rubbish to make sure it all goes into the right one”.

Already worse off than a “slum-dweller on a landfill site in Nairobi”, this injustice against an unfortunate pensioner is made all the worse, according to Michael Ware, by one “simple fact”:

“all rubbish can be sorted much more efficiently by machines without the need for any human intervention”.

Invested interest?

Let’s leave aside the fact that Ware is a partner in a company called BDO, which raises public funds for private sector clients wishing to build waste infrastructure. Let’s also park the question of why the frail Mrs Ware is left to do her son’s household recycling. Instead, let’s take his concern at face value.

After all, no one likes having extra work to do, especially when it is pushed upon you by the council (or worse, “EU bureaucrats”). It’s a common cause for complaint in many of the country’s newspapers, who feel their readers are anything from confused to outraged by being required to sort waste into multiple containers. The idea that technology could easily take over also regularly gets an airing.

But Ware’s claim that machines could save us all the trouble of separating our waste is a myth – or at best, a drastic overstatement.

A Surrey state of affairs

To understand this, let’s focus on Epsom. According to the local council’s website, their five collection containers consist of:

• A wheelie bin for residual waste (fortnightly);
• A wheelie bin for garden waste (fortnightly);
• A caddy for food waste (weekly);
• A box for paper, glass, and cans, along with household batteries, textiles and shoes (weekly);
• A wheelie bin for both rigid plastic and plastic film, along with cartons and cardboard.

If it all went in one bin instead, is there infrastructure that could separate these materials just as well as people do?

Well, the council could send the whole lot to:

• a mixed waste processing facility, or ‘dirty MRF’;
• a mechanical biological treatment (MBT) plant; or
• a mechanical and heat treatment (MHT) plant.

Each of these types of facility is designed to extract some recyclable material from mixed, residual waste. The sorting process will involve the waste being carried along conveyor belts, where it may subjected to magnets, eddy current separators, air classifiers and optical sorting. Some even involve a degree of manual separation.

The materials targeted vary from facility to facility, but almost all look to extract metals (because they are quite valuable and easy to sort). Some target plastics, and some glass, depending on factors such as market conditions and the quality of the material they are able to extract.

Bin day in Epsom? Photo SuSanA Secretariat (CC BY 2.0), via Wikimedia Commons.

A distinguishing feature of these plants is what happens to the material that remains once the target material has been extracted:

• in a dirty MRF, the residue is likely to be sent straight to landfill or incineration.
• in a MBT plant, the organic fraction of the waste is subject to some sort of biological process, such as aerobic composting, anaerobic digestion (AD) or biodrying, intended to obtain some value from the material (e.g. biogas, which can be burned) or to reduce the amount that remains. Depending on the properties of the end product (and the law in the country where it is produced!) it may be used as a compost (rare in the UK), as material to remediate land such as old landfill sites, or may be incinerated or landfilled.
• in a MHT plant the material is heated and sterilised; some may be sent for subsequent AD, while some may be sent for incineration or landfill.

Ewell have to sort it out

So, Ware is right to say there are facilities that sort mixed waste. But he’s dead wrong to suggest that they work anything like as well as source separation. Epsom & Ewell Council achieved a 46.8% recycling rate in 2014/15, and there is no residual waste sorting facility that comes anywhere close to this performance. The reasons are pretty obvious:

• like most councils, nearly half of Epsom’s recycling comes from composting garden and food waste. But it is nigh on impossible to produce good-quality compost from organic waste that’s been mixed with all sorts of stuff you wouldn’t want to spread on your vegetable patch.
• a large part – often more than half – of the dry recycling councils collect comprises paper and card. When this material has been mixed together with wet and greasy food waste, it will often become soiled beyond recovery, so it is rarely targeted for recycling by residual waste sorting plants.

Great claims have been made for residual waste sorting, but in practice facilities rarely recycle more than 15-20% of their input. This would go up if more recycling remained in the residual stream – but not by much. With recycling markets weak, the business case for the limited benefit these types of facilities provide has been looking somewhat shaky of late – whether for operators or councils.

Ware’s wally

Ware, then, is quite wrong to say ‘all rubbish can be sorted much more efficiently by machines without the need for any human intervention’. There is no machine that councils can invest in that will sort all rubbish. It may be too redolent of the slums for Ware’s taste, but as a minimum, source separation of dry and organic recycling from residual waste remains necessary in order to achieve high recycling rates.

The householders who invest a little time each day or week in sorting their waste deserve to be thanked for their efforts – not fed myths.