Remains of plastic tape left on cardboard boxes when a compost bin was emptied
Paper is almost a prerequisite for modern home composting but not all paper is the same and some is better recycled than composted. Where paper material is both compostable and recyclable the latter is usually
the better environmental option as it reduces the need to fell trees. Making paper from recycled material also requires less energy and uses less water than making it from timber.
There are those times however when home
composting is the better alternative provided the right bin or technique is used. There will be some waste e.g. where cardboard is contaminated with food materials which would contaminate the recyclable waste stream if put into the kerbside collection system
operated by councils e.g. greasy pizza boxes. Home composting is much better than the alternative of sending it to landfill. However, home composting all household paper using bins may not be practicable due to the volume produced and it may be necessary to
consider other methods such as Lasagne or sheet composting if space is available. Home composting can deal with some types of paper, such as tissues and shredded paper, which in many areas cannot be recycled or composted via the council kerbside collection.
There will still be some paper items that at present, have to be fed into the council landfill system. Concern is often expressed in some forums that printing inks are toxic and therefore printed paper should not be composted, this may well have been the case
in the past, but these are now banned, and modern vegetable inks are safe to compost.
While shredding and composting confidential paperwork containing financial and personal information provides security the this is not
the primary reason for composting shredded paper. Paper is an excellent source of carbon (cellulose) and a means of absorbing moisture from kitchen and catering waste.
If a hot composting batch system is being used,
where the objective is to produce compost quickly, the lower the lignin content of the paper the better as the woody lignin is slow to breakdown ( Composting Woodchip).
In cold composting the actual time taken for the paper to decompose is not so important as the normal processing period is much longer and it does not matter if some recognizable paper is present in the final compost as it can easily be put back into the bin.
Shredded paper will need mixing/aerating in the bin so that it does not form a wet mat which may restrict airflow in the bin with the risk of localised anaerobic conditions.
This should be recycled rather than sent to landfill
and can help councils to earn money by selling it on.
Paper can be produced by one of two techniques. In the first a Chemical Process is used to produce the higher quality paper e.g. office and computer paper while
the cheaper grades of paper such as newsprint are produced by mechanical processes. The chemical process removes most of the lignin, leaving only about 5% in paper and 10% in corrugated cardboard compared with 30% in newspaper. As mentioned lignin is
slow to compost while the cellulose left after treatment breaks down quite quickly. Hotbin reports that office paper and corrugated cardboard will break down in days/weeks in one of their bins compared with months in the case of newsprint. This is why
I tend to recycle my newspapers while shredding and composting all my “office” paper.
The papers with the highest cellulose and lowest lignin content are computer paper, envelopes (in the case of window envelopes
it may be necessary to remove the windows [see below] corrugated cardboard, writing and drawing paper, pages torn from telephone directories (some still exist) and instruction leaflets/ sheets. In the slower decomposing/ higher lignin group we have cereal
packets, printed cards (avoid glitter), newspapers and cardboard egg cartons (good for trapping air in the bin). I would suggest that glossy leaflets and magazines are best recycled. Wrapping paper if untreated is compostable do the scrunch test.
Receipts are coated with BPA and are not compostable or recyclable.
Windows Envelopes. Some of the windows are made from industrial compostable PLA but others are made from plastic
and will not compost yet others are made from glassine (a recyclable paper product), polystyrene, polypropylene, polyester or acetate. The trouble is that you can’t always tell the difference only some envelopes come printed with content information.
But does it really matter if home composting if you want to put the envelopes in the compost bin either remove the window before they are put in the bin (or shredded) or pick it out at the end of the composting process if it has survived the process.
After all most composters will be used to removing the remains that parcel tape that has somehow managed to get into the bin or wormery on corrugated cardboard.
If it is proposed to recycle window envelopes it is recommended
to check with the local authority as to whether they are can be recycled under their contract and whether the windows should be removed first. While most envelopes with plastic windows can be recycled with the rest of your paper there are
still some local authorities where envelopes are not collected (due to the glue) while others request the window to be removed.
There are two main types of types of cardboard that can be easily composted. Flat carboard such
as cereal boxes, and shoe boxes, these may contain print and pictures, but the ink is compostable (see above). Corrugated is usually used to make packing boxes has the advantage of having air spaces in the corrugations.
cardboard – This includes cardboard that has been laminated with another material, such as wax (coated paper cups) or non-degradable foil lining (pet food bags). These types are more difficult to compost but they are not widely used. Thinner,
non-corrugated cardboard which is used in a wide range of consumer packaging, such as cereal boxes is not waxed. Waxy cardboard is mainly used for things like produce boxes thatused by suppliers to deliver to shops and restaurants.
It is actually not likely that residential homes will recieve a lot of waxy cardboardf. People often confuse waxy cardboard with glossy cardboard or paper.
Large pieces of cardboard will not decompose as quickly and ideally the cardboard
would be shredded before being added to the compost bin but even if time was available to shred the cardboard many home shredders would not be able to cope with it. It is particularly important not to shred card with tape attached before
composting as this will result in the release of microplastics into the soil. So, the normal advice is tear or cut it into small pieces depending on the size of the pieces they could also be scrunched up rather than left flat. Any tape or stickers
that will not breakdown should be removed especially if these contain plastic.
Soaking the cardboard in rainwater or the liquid from soaking weeds to drown them before composting will help to speed up the decomposition process of larger pieces.
Larger scrunched up pieces of cardboard boxes could be used at the bottom of a dalek bin with twigs to provide some air space or as the base layer in New Zealand bin. Otherwise it can be added as when it becomes available or as a separate brown layer.
Envelopes : The
EMA Guide to Envelopes & Mailings [PDF]