CEM - Abstract

Abstract Title: SRM EN 13211 isokinetic sampling coupled with on-line and continuous analytical system for Mercury speciation in flue gas: waste water treatment sludge in a combustion / co-combustion municipal solid waste incinerator case-study
Presenter Name: Dr Paolo Lopinto
Co-authors:Dr Silvia Bellinzona
Mr Andrea Ceolin
Dr Maria Grazia Perrone
Mr Marco Zonca
Dr Federico Teoldi
Company/Organisation: TCR TECORA Srl
Country: Italy

Abstract Information :

This work presents the results of 5 months from the start of the F.A.N.G.H.I. project (Lombardy Region: ERDF ROP 2014-2020 Innovation & Research Call Hub). The project provides for a total cost of € 9,904,708.53, a duration of 30 months starting in January 2020.

F.A.N.G.H.I. proposes an integrated approach to assessing health impact -environment of two alternative strategies for the exploitation of waste water treatment sludge to identify the most advantageous (or combination of two) in terms of sustainability, i.e. in economic, health, environmental and energy terms. Materials and methods used to determine mercury emitted by the exhaust from two different production cycles of mono-incineration and co-incineration of waste water treatment sludge are described. In Europe, the manual wet chemical method according to EN 13211 is used as a reference method for the determination of the total mercury concentration in flue gases. Although mercury is mainly present in the gaseous form, it can also be found in the dust phase as well as in droplets which can be present after wet scrubbers. Therefore isokinetic sampling is necessary in order to collect dust and droplets correctly. During fuel combustion, mercury in the form of Hg0 and Hg2+ is emitted to the atmosphere. Effective reduction of mercury emission requires the application of speciation systems for emission control. An isokinetic sampling system capable of collecting particle phase (dusts and droplets) of the mercury was coupled to, as regards gas phase, a measurement system based on the continuous SnCl2 reduction and real-time CVAAS measurements. Unlike the wet absorbtion method, real-time gasesous mercury reading can be obtained throughout sampling and measurement period. The system was also capable to perform real-time speciation measurements on both elemental mercury and total gaseous mercury simultaneously with combination of two setup. In the first setup (first scrubber), the Hg2+ is reduced to Hg0 using a wet method (10% SnCl2 solution). Then, the sum of Hg0 is determined by means of the first detector. The second setup is responsible for determination of Hg0 only. Before Hg determination by the second detector, Hg2+ is removed from the flue gas by using a 10% KCl solution (first scrubber). Concentration of Hg2+ in the flue gas is calculated from the difference of total Hg concentration and concentration of Hg at the zero oxidation state. Interfering substances (e.g. HCl, SO2) are removed from the flue gas with a 10% KOH solution (second scrubber), the moisture is removed by the third scrubber, whose temperature is reduced to 5 °C. The solutions in the scrubbers may be discharged and replaced automatically at a specified time. At determined intervals (typically every 60 s), the detector controls the background level using a gold trap which removes Hg from the flue gas and corrects the analytical signal. With this configuration, the complete characterization of the exhausts with regard to mercury in the two different methods of waste water treatment sludge treatment is approached.