No abstract

No abstract

A novel process for the controlled desorption and immobilization of mercury (Hg) in industrial waste water treatment plants is introduced. Research is conducted with particular reference to waste water streams from wet flue gas desulfurization (FGD) in coal-fired power plants. Experiments are carried out with a continuously operated lab-scale wet FGD system and a batch-wise operated waste water treatment unit. By aeration of the liquid phase, the controlled de-sorption of Hg during the alkalization process of the waste water treatment is enhanced. It is demonstrated that Hg is emitted in its elemental form (Hg0). Linear dependency of Hg0 formation on sulfite-and hydroxide ion concentration indicates first-order dependency of reaction kinetics. Decreasing concentration of Hg0 in the exhaust air for increasing Clconcentration is observed. The results show exponential dependence of Hg0 mass transfer on stirring speed and almost constant emitted mass flow of Hg0 for all aeration flow rates investigated. For pH 9, 35 % of the total Hg 2+ inventory is stripped from the waste water per hour. The new concentrated sink for mercury increases sustainability and reduces the consumption of precipitation agents. The findings could be used for further development of the proposed process as well as for the prevention of unnoticed Hg emissions.

No abstract