Leaching Characteristics of Mercury Waste and Prediction of Long-Term Leaching Behaviour

Abstract

Some of mercury species are known to be potentially highly toxic to humans in trace amounts. Elemental mercury was used as raw materials for industrial facilities and then released into the environment in the form of by-product. According to Article 11 of Minamata Convention on Mercury, mercury wastes are categorized as three types of wastes: Hg consisting waste, Hg containing waste and Hg contaminated waste. Mercury wastes are classified as hazardous wastes or general wastes and are finally landfilled. Mercury compounds contained in landfilled mercury waste are likely to be released into the environment by their leaching characteristics. Therefore, sequential extraction procedure was applied to mercury waste in order to identify the leaching characteristics of mercury waste. The sequential extraction procedure consists of five steps depending on the pH of the extraction reagent, and the major mercury compounds are leached out from different five steps. Also, leached mercury compounds in steps 4 and 5 such as mercury sulphide, which were chemically stable bounded. Therefore, in this study, a long-term leaching test was conducted to identify an effect of solidified and landfilled mercury waste on landfill site when exposed to the environment in the long term.