Pollutant formation and emissions from cement kiln stack using a solid recovered fuel from municipal solid waste

Area of Science:

• Environmental Chemistry
• Combustion Science
• Waste Management

Background:

• Solid Recovered Fuel (SRF) utilization in industrial processes is increasing.
• Understanding the environmental impact of SRF thermal decomposition is crucial.
• Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are significant combustion byproducts.

Purpose of the Study:

• To investigate the formation of PCDD/Fs during SRF thermal decomposition under varying atmospheric conditions.
• To quantify emissions of various pollutants from SRF co-combustion in a cement kiln.
• To assess the influence of SRF input on pollutant formation and emission levels.

Main Methods:

• Laboratory-scale horizontal furnace experiments analyzing PCDD/Fs evolution.
• In-situ emissions monitoring in a cement kiln utilizing different SRF proportions.
• Analysis of pollutants including PAHs, PCDD/Fs, metals, and acid gases.

Main Results:

• Sulfur presence was identified as a key factor in PCDD/Fs formation.
• Dioxin toxicity in the lab furnace peaked near stoichiometric oxygen conditions.
• Cement kiln emissions for all monitored pollutants remained below regulatory limits.
• No direct correlation was found between SRF input rate and metal emissions.

Conclusions:

• SRF thermal decomposition can be managed to control harmful emissions.
• Sulfur content in SRF requires careful consideration to mitigate PCDD/F formation.
• Co-firing SRF in cement kilns is a viable option with controlled emissions.