St Nicks

Centre for nature and green living

Biodegradable or Compostable: what’s the difference?

Biodegradable and compostable are words that are often used interchangeably but they really shouldn’t be. Biodegradable refers to any materials that break down in the environment – for example a plastic bag over time will disintegrate into smaller pieces but these can still be harmful to organisms and soils. Compostable items on the other hand are made of organic matter which micro-organisms decomposers are able to completely break down to form a nutrient rich soil or “compost”, such as food waste and plants. Even human bodies could be composted, as is explained in this blog which is not for the faint hearted!

Image on the left is the remains of “degradable” waste washed up on a beach. The image on the right shows food waste and the compost it becomes.

You may have noticed an increase in the amount of plant-based plastics (PLA) cropping up since the public awareness of the hazards (and longevity) of plastics has increased. These are usually labelled as “biodegradable” and whilst they might decompose faster than conventional plastic they can still take hundreds of years and may not ever break down if sent to landfill.

On the recycling round we’ve noticed an increase in the number of laminated flyers – you know the ones, usually sent by estate agents or restaurants advertising their services. Even when laminated in plastic, these are often labelled as biodegradable (or recyclable, which they definitely aren’t!). When these items end up in the recycling stream they reduce the quality of the end product. When these items break down into smaller pieces it just makes it easier for them to end up in food chains.

This image shows some of the bioplastics tested in the study carried out by Team Marine after two years of submergance in the sea.

The BAN list series of reports published by 5 Gyres (read the latest version here) reviews the use of plastics and lists the ones with the worst impact on the environment. Of most interest to this post however is their synopsis of a study carried out by the students of Team Marine, an ocean conservation organisation. They put all sorts of items (from dog waste bags through to eco wipes, cups, straws and utensils) that were branded and certified as compostable or biodegradable into the sea for two years and looked at how accurate the standards and claims were. The results showed that most bioplastic products persisted in the environment in the same way as their petroleum based counterparts. They concluded that bioplastics should be restricted in the same way as single use plastics. Most of the products they tested were American (though a few brands such as Huggies are available in the UK) but it really is an interesting read. You can see the results with images at each stage of decomposition from page 16 of the report linked above.

Compostable items made from natural materials like sugarcane fibre or bamboo (such as VegWare) are widely advertised as a green alternative to plastics or single use items but may only break down in commercial composting facilities. Currently there is no standard certification in the UK which clearly and reliably labels items as truly compostable at home.  If you compost at home you’ll know that it doesn’t take that long – several months or a year – for truly compostable items, which include paper and cardboard, to be unrecognisable.

We’ve attempted to compost so called bioplastics a couple of times within our own compost heaps and had no success. If you have successfully composted a bioplastic at home please let us know. Composting at home can be really easy, clean and pest free. If you need any advice or inspiration please get in touch and we’ll do our best to help.

It is a confusing situation so what can be done? If you find companies using the terms biodegradable or compostable without explaining what exactly they mean and under what conditions the materials will compost challenge them on their use of this language and avoid purchasing the product if you are unsure. In the case of unsolicited laminated leaflets/flyers you can contact the company that has sent them – we’ve had great success with a number of York based estate agents when we asked them to make better choices when designing their flyers. You can also cut down on the amount of junk mail you get by putting a “no junk mail”, “no commercial leaflets” or “no free newspapers sticker” on your letterbox or using the Royal Mail Door to Door Opt out.

20 March 2018 | Categories: Inspiration, Waste and recycling | Tags: biodegradable, break down, compost, decompose, green washing, home compost, plastics, time