Anaerobic digestion is a series of processes by which microorganisms break down biodegradable material in the absence of oxygen. Such processes are used for industrial or domestic purposes to manage waste, or to produce fuel (methane also known as biogas), and compost.
Batch composting simply involves mixing all your organic waste together at once and then letting it decompose without adding any more material (except water), until it turns into compost.
Biodegradable plastic can be broken down into water, biomass, and gases such as carbon dioxide and methane. Biodegradability depends on environmental conditions such as temperature, humidity, the presence of oxygen, and microorganisms.
Bioplastics is a rather confusing term that encompasses a range of different materials that are either bio-based, biodegradable, or both. Bio-based bioplastics are made using polymers derived from plant-based or microorganism sources such as starch, cellulose, lignin, or polylactate. Bio-based bioplastics can be engineered to be biodegradable; equally they can be engineered to be chemically identical to petroleum-based plastics such as non-biodegradable polyethylene.
Biogasification is an industrial process whereby biomass is converted into biogas, which can then be used as fuel.
Carbon sequestration is the removal and storage of carbon dioxide from the atmosphere by natural or artificial processes.
Cold or passive composting
Cold or passive composting uses many of the same ingredients as hot composting, but requires less maintenance and effort, i.e. no digging or aeration of the heap. The resulting internal temperature of your compost heap or bin is therefore much cooler, and so it takes longer for the organic waste to decompose into compost.
Compost is organic matter that has been decomposed in a process called composting. This process recycles various organic materials otherwise regarded as waste products and produces a soil conditioner (the compost).
Compostable materials are a subset of biodegradable plastics that break down safely into water, biomass, and gases under composting conditions. Industrial composting conditions are the most favourable: temperatures of 55-70℃, high humidity, and oxygen. Materials that break down in industrial composters may not break down under home composting conditions.
Continuous composting involves adding organic waste to a compost heap or bin continuously in an ongoing process. Commonly, continuous compost heaps consists of highly decomposed matter with compost underneath and fresh waste on top.
End-of-life is a term used to indicate the stage of a product, process, or system when it is disposed of and/or recycled.
Global warming potential (GWP)
Global warming potential (GWP) is a measure of greenhouse gas emissions in terms of their potential to trap heat in the earth’s atmosphere, relative to carbon dioxide, in a specific time horizon.
Home composting is a general term for the process by which biodegradable garden waste or domestic food waste is collected and placed in either a container or heap to allow natural processes to turn it into compost. It is a manual process whereby the composition and process temperatures remain largely unregulated. Both aerobic and anaerobic conditions can occur in home composting, although aerobic conditions are more normal. The time frame for home composting depends on personal preference and the use to which the compost is put, but 3-12 months is typical.
Hot or active composting
Hot or active composting is a method whereby microbial activity within the compost pile is at its optimum level, resulting in a higher internal temperature of your compost heap or bin, and the quick decomposition of organic matter into compost.
In-vessel composting (IVC) generally describes a group of methods that confines the composting materials within a building, container, or vessel. In-vessel composting systems can consist of metal or plastic tanks or concrete bunkers in which air flow and temperature can be controlled, using the principles of a ‘bioreactor’. Generally the air circulation is metered in via buried tubes that allow fresh air to be injected under pressure, with the exhaust being extracted through a biofilter, with temperature and moisture conditions monitored using probes in the mass to allow maintenance of optimum aerobic decomposition conditions.
Windrow industrial composting
In agriculture, windrow composting is the production of compost by piling organic matter or biodegradable waste such as animal manure and crop residues in long rows (windrows). This method is suited to producing large volumes of compost. These rows are generally turned to improve porosity and oxygen content, mix in, or remove moisture, and redistribute cooler and hotter portions of the pile. Windrow composting is a commonly used farm-scale composting method. Composting process control parameters include: the initial ratios of carbon- and nitrogen-rich materials, the amount of bulking agent added to assure air porosity, the pile size, moisture content, and turning frequency.
Life cycle assessment
Life cycle assessment (LCA) is an environmental assessment methodology used to analyse the environmental impacts associated with resource utilisation and emissions at each stage of a product, process, or system’s life cycle.
If you compost and want to take part in a home composting experiment, you’ll need:
- a selection of identical compostable or biodegradable items (see list below)
- a net bag and clip to securely close it (see guidance below)
- a plastic milk bottle cap (or similar) and permanent marker pen to identify your items
If you do not use a composter but you're interested in finding out more, please see our Composting Processes page for more information.
1. Choose your experiment items
Select the type and quantity of compostable or biodegradable plastic items from our list that you would like to test. Please only select items that display the following manufacturer information:
- 'compostable' (only)
- 'home biodegradable'
- 'home compostable'
- 'suitable for home composting'
- TUV OK Compost 'HOME' certification mark
- Din Certco 'HOME COMPOSTABLE' certification mark
NOTE: If testing multiple items together please ensure they are an identical type and brand (one type and brand of item per net bag).
2. Prepare your experiment equipment
To make locating your experiment items in your compost easier, please compost your items in a plastic net bag (the kind of net bag used to hold fruit in a supermarket would be ideal). Use a permanent marker pen to identify your items on a plastic milk bottle cap (or similar) and add to your net bag. To test fruit and veg stickers please stick each label on a plastic milk bottle cap first then add to your net bag. Use a permanent marker pen to identify them. You will have the option to upload photographs of your composter and experiment equipment to help us analyse your results. See our Photography Guidelines for more information.
NOTE: Please ensure you use a perforated net bag. This is so a sufficient flow of oxygen, organic waste and microorganisms can come into contact with your experiment items.
3. Create a login account
Create a login account and share a few extra details about what composter you will be using for the experiment, its location in the UK for our Live Composting Map, and your composting method. Please set the duration of your experiment according to how long it usually takes you to make compost. There is the option to share photos of your composter and experiment items and equipment, if you wish. Please indicate on your form if you would like to share your images on the Big Compost Experiment website. See our Photography Guidelines for more information.
4. Start your experiment
Securely close the net bag containing your experiment items and identifying markers and add to your composter. Carry on composting as usual. We'll send you an email reminder when your experiment is due to finish and it's time to look for your net bag and items.
5. Submit your results
When your experiment timer has finished, please look for the net bag and items in your compost. You can use a trowel, spade or household sieve to locate it. Under 18s must be accompanied by a responsible adult. Check the contents of your net bag for any traces of your items. If there are any traces please compare them with our 'Scale of Degradation' in the results form in your login account and share any other useful observations about your experiment. There is the option to share a photo of your results. Please indicate on your form if you would like to share your image(s) on the Big Compost Experiment website. See our Photography Guidelines for more information.
NOTE: Once you have completed your experiment, please dispose of any item remains in your general waste collection. Check locally for recylability of other experiment equipment and rinse before recycling.
How to take a photograph of your experiment equipment
Pre- and post-composted items and equipment
- Place your biodegradable or compostable items on a clean surface alongside any secondary packaging (if applicable) and net bag. A contrasting surface is preferable (i.e. one on which the items will stand out).
- Orientate items and packaging (if applicable) in order to capture any compostable labelling or certification marks (if displayed). If testing multiple items together please ensure they are an identical type and brand (one type/brand of item per net bag).
- Position your camera approximately 1 metre above the objects. Position items clearly within the viewfinder of your camera or camera phone, so that all edges of items are visible. Please ensure no recognisable features (people, faces, house number, etc.) are visible in the image.
- Take a photograph (while keeping your hand steady!)
- Upload photographs via your login account, with the option to display them on our Gallery page.