Stabilization of persistent organic pollutants (POP) in flue gases in a biological waste incinerating facility

P. Jirsa* and J. Malaťák

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Praha-Suchdol *Correspondence: pjirsa@tf.czu.cz

Abstract:

The article focuses on a technology of flue gases stabilization in biological and hospital waste incinerating facility. Hazardous particles and compounds formed in flue gas during the process of thermal waste degradation need to be stabilized according to an enacted legislation. The aim of the research is to examine technological process of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/F) elimination in flue gas. PCDD/F is group of persistent organic pollutants which are resistant to environmental degradation and are highly toxic for the environment in very small amounts. Experiments were performed in semi operation hospital waste incinerating plant with heating power 1.5 MW and capacity 250 kg h^-1 of incinerating material. It was observed that formation of PCDD/F exponentially grows with increasing concentration of chlorides in the flue gas, but formation varies based on type of congener. The highest concentration was measured for HxDF, 17,522 pg Nm^-3 and HpDF, 16,334 pg Nm^-3 at chloride concentration of 867 mg Nm^-3. However, concentration of PCDD congeners didn´t exceeded 4,000 pg Nm^-3 for the same level of chlorides in flue gas. Two types of activated carbon Chezacarb and NORIT were tested for capability to stabilize PCDD/F in flue gas. Results show that refining effect for both sorbent are very similar. It was observed that 0.1 g of activated carbon should be applied per 1 Nm³ of flue gas in regard to reduce 3–4 ng Nm^-3 PCDD/F under required emission limit.

Key words:

activated carbon, hospital waste, PCDD, PCDF

Dry sorption stabilization of flue gases in biological waste incinerating facility with heating power under 5 MW

P. Jirsa* and J. Malaťák

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Praha-Suchdol, Czech Republic
*Correspondence: pjirsa@tf.czu.cz, jirsa.petr@gmail.com

Abstract:

Biological and medical waste is always classified as hazardous material such as it must be treated according to its hazardous characteristics. One of the best methods for disposal seems to be a thermal degradation. This research examines the effect of finely crushed sorbent Ca(OH)2 and NaHCO3 to eliminate these hazardous substances in a small incinerating facility with heating power under 5 MW. The experiment took place in an existing incinerating plant with capacity 250 kg h-1. Sorbents were injected into a flue gas flow at two different places. It was observed that the temperature of flue gas and the residence time significantly influence the sorbent refining effect that is caused by quantity of collision in flue gas stream. Sorbents were dosed into a system with a theoretical consumption excess to serve sufficient refining effect. At dosing rate of 7 kg h-1 Ca(OH)2 the concentration of SO2 decreased by 34.5% and HCl by 59.0% referring to the initial concentration. At dosing rate of 5 kg h-1 NaHCO3 the concentration of SO2 decreased by 32% and HCl by 44.8% referring to an initial concentration. Tested sorbents react with acidic compounds with different efficiency and preferably react with different acid compounds.

Key words: