Treatment of Mercury Contaminated Waste in a Two Stage Process, Pre-Treatment, Volume Reduction and Subsequent High Temperature Oxidation

Mercury is known to be present as a trace-gas in the Rotlieg-end natural gas reservoirs. In the gas reservoirs under consideration levels of between 0.3 - 0.5 mg/Nm{sup 3} are found. During the gas treatment process the mercury is removed together with water and higher hydrocarbons. All waste streams, for example sludge, which are accumulated in gas treatment units and equipment e.g. glycol- and coalescence filters and heat exchangers are contaminated with mercury. In the past this mercury contaminated waste has been disposed of at special dump sites such as in depleted salt mines in Germany. In order to reduce the impact on the environment, NAM decided to develop an alternative method of disposal. From a feasibility study it was concluded that proper conditioning of the waste streams followed by a thermal oxidation process would be the best option to clean mercury contaminated waste. As there was no suitable thermal treatment process available, an in-house research laboratory was approached. Their investigation resulted in a {open_quotes}High-Temperature-Oxidation (HTO){close_quotes} process. On this basis NAM decided to build availability where all its mercury contaminated waste could be treated. It consists of two separate processes; i.e. the pretreatment and volume reduction facility and the finalmore » treatment using the HTO - process. This paper gives an overview of the required pretreatment facilities, describes the HTO-process and summaries the achieved treatment results.« less