Waste hazardous property assessments are required to ascertain the ‘worst case’ compound present for certain elements. This includes all compounds in the Classification, Labelling and Packaging (CLP) Regulation 1272/2008/EC, whether the compounds have harmonised or non-harmonised classifications. This introduces an extra 200+ zinc compounds into the assessment according to EA guidance WM3 (http://bit.ly/1SQ2SL6).
Some zinc species are ecotoxic at the zinc concentrations available as dietary supplements for humans, yet no routine methods are available for determining whether total zinc concentrations in wastes are in an ecotoxic form.
With partners at ECN, WRc has undertaken specialist testing and geochemical fingerprint speciation modelling to determine the controlling phases of zinc present in incinerator bottom ash (IBA). In projects for the Environmental Services Association the majority of zinc phases in IBA from municipal waste have been shown to be non-ecotoxic compounds. This has allowed the concentration to be used in the waste hazardous property assessment to be reduced and the ash to be classified as non-hazardous, thereby reducing the quantity of waste being landfilled.