Uncertainty over Classification of Bottom Ash

Posted on: August 10, 2009

Bottom ash is currently classified as non-hazardous waste and around 55% is sent to non-hazardous landfill and the remainder is weathered (through exposure to air and rain) before being used as aggregate.

However, the Environment Agency has recently admitted that it does not “have 100% confidence…” in the classification of IBA as non-hazardous due to it’s potential eco-toxicity. Concern over the eco-toxicity dates back to 2005 when the Health and Safety Executive reclassified zinc oxide, often present in IBA, as eco-toxic.

In 2008 The Environment Agency said that it was likely to reclassify IBA as hazardous but shortly after went back on this suggesting that zinc was likely to be present as a benign complex mineral rather than the ecotoxic zinc oxide. Contrary to this, recent tests on a Dutch municipal waste incinerator led by Germany’s Environment Agency revealed that the IBA was ecotoxic.

The Environment Agency currently have a technical working group assessing IBA’s impact on water and health but not on whether the material is ecotoxic or not.