Dust to dust, ashes to...what?

Researchers in China have used a raft of analytical techniques to investigate the nature of the "bottom" ash from inefficient medical incinerators. Their findings suggest that improvement in incinerator operation and efficiency are essential if the ash is to be recycled as an engineering material for the construction and road transport industries. Lijuan Zhao and colleagues of the Chinese Academy of Sciences, in Beijing, found a range of toxic heavy metals, as would be expected in such ash, but leachate is below safety limits. However, the presence of polyaromatic hydrocarbons at high levels is troublesome and suggests that incinerator protocols should be improved to make the ash more suitable for recycling.