How to Recycle our Home Compostable bags – Plants v Plastic

Plants vs Plastic – Does Plant based packaging work?

We’ve talked about the problems of plastic pollution and recycling and this moves us on to the question – what are the alternatives?
Firstly there are some terminologies that you may have encountered…
– Biodegradable
– Industrially or Commercially Compostable
– Home compostable

Biodegradable

Biodegradability of a material means that a substance can be decomposed by biological processes – that is, by living microorganisms for example bacteria and fungi.
Ideally, the product is completely converted into water, CO2, and biomass during that process.
Biodegradation doesn’t require any human intervention and is a natural process. How quickly or slowly that degradation takes place isn’t specified in the definition of “biodegradable”.
So the rate of degradation depends on environmental conditions, including temperature, humidity, and availability of oxygen (although biodegradation can occur with and without oxygen). Essentially all materials are biodegradable to some extent.
There are two different types of biodegradable plastic:

Vegetable-based plastics, which are also loosely known as “bioplastics” or “compostable plastics”, are tested in accordance with ASTM D6400 or EN13432 as to their ability to biodegrade under conditions found in industrial composting or biogas facilities.
Oxo-biodegradable plastics—which are made from polymers such as polyethylene (PE), polypropylene (PP), or polystyrene (PS) contain a prodegradant catalyst—often a salt of manganese or iron. Oxo-biodegradable plastic will degrade in the presence of oxygen much more quickly than ordinary plastic.
In theory the plastic material has then been converted into small-chain organic chemicals that are no longer plastic and are biodegradable by bacteria. The timescale for complete biodegradation in the open environment is much shorter than for “conventional” plastics, which in normal environments are very slow to biodegrade.
It is important to distinguish between “oxo-degradable” plastics, which fragment but do not biodegrade except over a very long time, and “oxo-biodegradable” plastics, which degrade and then biodegrade.

Industrially or Commercially Compostable

Composting is a human controlled biodegradation process usually used to improve the soil. In commercial composting higher temperatures and controlled microbe conditions are used in industrial plants.
Under EU standard EN 13432 a material can be considered compostable if…
– At least 90% biodegrades within 6 months
– There are no more than 1% additives which must be non-toxic and have no negative effects on plant growth
Kerb side Garden Waste collections are usually commercially composted.

Home Compostable

Home compostable packaging can be put into your own garden compost heap. Garden compost heaps reach lower temperatures than commercial compost heaps and conditions are less controlled. Hence not all industrially compostable materials will degrade in a garden compost heap. So materials need to be certified as Home Compostable.
Currently there are few bodies that certify for Home Compostability – TUV Austria is the only organisation we know of – http://www.tuv-at.be/home/

Summary

So all compostable packaging is biodegradable, but not all biodegradable packaging is home compostable.
You could say that at least in terms of recycling the order is…
Best
– Home Compostable
– Commercially Compostable
– Biodegradable

Worst

At Lick the Spoon we are using Home Compostables where we need a food contact safe barrier, or in many cases Food contact safe cardboard.

Types of Kerbside Waste Collection

Garden Waste

When the garden waste arrives at the composting site any material that is not compostable is removed, the remaining waste is then shredded and then laid out in a long pile to decompose, usually in the open air.
The process at a composting site is similar to that that takes place in home compost bin, but is actively managed to speed up the process. However, due to the amount of material the temperature reached is a lot higher than in a normal household compost bin. Temperature can reach up to 60°C. This higher temperature means that the enzymes and bacteria are quickly put to work resulting in finished compost in just a few weeks.
The material is turned frequently to provide much needed oxygen to micro organisms that help decompose the material. High temperatures kill off any harmful microbes, weeds and plant diseases.
The final part of the process involves screening the compost to remove any remaining contaminants and to grade the material for various end uses. Any compost that is still oversized or hasn’t decomposed enough, can then be put back through the process until it has composted down sufficiently.
The whole process takes between 8 and 16 weeks, depending on the final use for the compost.
A potential issue with recycling compostable and home compostable materials in Garden Waste is that as they are relatively new, and are not dissimilar to plastic in appearance they may be screened out even though they are suitable for composting. Currently our own Wiltshire Garden Waste collections don’t allow compostable materials for example.
https://www.recyclenow.com/recycling-knowledge/how-is-it-recycled/garden-waste

Food Waste Collections

Many councils now collect food waste. Depending on your council food waste can be recycled in different ways.
In-vessel composting – the council facility will mix food waste with garden waste, shred it and then compost it in an enclosed system for around 2-4 weeks at temperatures up to 70°C speed ensuring any harmful microbes are killed off. The material is then left outside to mature for a further 1-3 months with regular turning and checks to ensure quality before going on to be used as soil conditioner.

Anaerobic Digestion uses microorganisms to break down food waste, animal manure, slurries and energy crops in the absence of oxygen, inside an enclosed system. As it breaks down it gives off methane, which is collected and converted into biogas and used to generate electricity, heat or transport fuels. It also creates a nutrient-rich digestate that can be used as a fertiliser for agriculture and in land regeneration.

Food Waste collections allow the use of compostable bags to line the caddy so your bags can be placed in Food Waste in a reasonable proportion. 

From 2023 it is likely that DEFRA will roll out a National food waste collection scheme.

Controversy?

Compostable and Home compostable materials are very new and consequently local authority waste collections may have difficulties identifying them as non-plastic materials.
This issue was raised in The Times recently…
From the Times June 7 2019

“Shoppers are being misled by disposable cutlery, packaging and nappies that are labelled as “compostable” but will not break down for years, scientists have warned.
Some high-street chains have been offering a range of compostable alternatives as consumers turn away from single-use plastics.
However, most of these products are only guaranteed to decompose in industrial composting plants in conditions that cannot be reproduced in a garden compost heap. Most local authorities do not have systems for collecting and dealing with them.
This means that the majority are destined for landfill sites, where they may not decompose for years, said Professor Mark Miodownik, a materials scientist at University College London. “The public really need to know that when something says it’s compostable, it is not going to disappear as soon as you drop it and it may not actually be good for the environment,” he told the Cheltenham Science Festival.”