Waste characterisation (waste characterization US) is the process by which the composition of different waste streams is analysed. Waste characterisation plays an important part in any treatment of waste which may occur. Developers of new waste technologies must take into account what exactly waste streams consist of in order to fully treat the waste. The biodegradable element of the waste stream is vitally important in the use of systems such as composting or anaerobic digestion.
Municipal waste streams are commonly broken down into the following constituents:
Biodegradable fraction
The first step in characterising waste is to decide on the appropriate EWC code. The list of these codes is available from the Environment Agency's website in the guidance document WM2. These codes carry three categories - absolute non-hazardous, mirror entries and absolute hazardous.
Absolute hazardous entries are hazardous not due to the composition of the waste but by virtue of the process that produced it, the same is true for non-hazardous absolute entries. Mirror entries can either be hazardous or non-hazardous depending on the composition of the waste.
Deciding whether a mirror entry is hazardous or non-hazardous by composition involves reference to the Approved Supply List (ASL) initially. If a substance is not listed in the ASL then the regulations permit the use of other sources such as Manufacturer's Safety Data Sheets (MSDS) to classify the waste. These documents contain Risk Phrases, which describe the hazards that the substance or substances present. Risk phrases have threshold values attached to them that indicate what concentration of a substance must be present in order for the waste to be classified as hazardous by the Hazard Code attached to the Risk Phrase.