Testing for biodegradability means going through a series of test methods to ensure a product will biodegrade at the end of its life and under certain circumstances. One internationally accepted method used for this is the BS EN ISO 14855; Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions – Method by analysis of evolved carbon dioxide. The main test method for this in the standard BS EN ISO 14855 using a system based on mature compost as the solid bed, which provides nutrients and an inoculum (this refers to our compost). The inoculum is formed of many substances, such as trees, leaves, food waste, etc. which consumes the material, leading to biodegradation. The components produce heat when breaking down the material, which in turn produces more CO2.
The test requires the set-up of nine flasks. Three contain just the mature compost, three more contain the mature compost and a negative material (something that will never biodegrade e.g. plastic). The last three contain the mature compost and a positive material (something that will always biodegrade e.g. paper).
This process takes place over a period of six months, measuring how much carbon in the material converts to CO2 and how long it takes to convert and to which extent the product has disintegrated. For a product to be certified as biodegradable under BS EN 13432, test standard BS EN ISO 14855 states that 90% CO2 must be produced by the end of the six months.
Once this process has been complete, the compost is able to be tested to see whether or not any ecotoxic residue has been left in the bed after the ultimate biodegradation of the product. This helps to ensure there are no negative or harmful effects on the compost, which would leave it unusable.