Mercury behaviour in flue gas from sewage sludge incinerators and melting furnace

Thermal conversion of sewage sludge can be a clean source of renewable energy if the emission of air pollutants from the source is controlled. In 2013, the Minamata Convention on Mercury was adopted, placing greater emphasis on the control of mercury emissions, including mercury emissions from sewage sludge incinerators. To characterise the behaviour of mercury in flue gas, particulate and gaseous mercury concentrations in two incinerators and a melting furnace were measured by manual sampling. In a third facility, continuous emission monitoring was used to characterise temporal trends in gaseous mercury concentrations. Wet scrubbers were determined to be effective air pollution control devices suitable for mercury removal. Stack mercury concentrations were found to be <10 μg/Nm³, which meets the mercury emission standard for existing plants (50 μg/Nm³).