Identification of metal concentration fluctuations in waste-to-energy plant flue gases—a novel application for ICP-OES

Abstract

A mobile continuous emissions monitoring laboratory, based on ICP-OES technology, was used to study temporal variations in metal concentrations in the flue gas of a waste-to-energy plant. The concentrations of over 30 elements were monitored prior to flue gas clean-up. Despite harsh analytical conditions, with high particulate loading, variable gas matrix and high concentrations of numerous elements, semi-quantitative measurements were made. Realistic detection limits in the range 0.007–0.06 mg m⁻³ were achieved. For many volatile metals, significant variations (4–18 mg m⁻³ for Na, 0–0.18 mg m⁻³ for Cd) were observed, and were linked to properties of the metal in question, to incinerator operating conditions, and to variations in the waste feed charge. The concentrations of some metals were attributable to specific sources in the waste. It was concluded that better waste segregation could significantly reduce the concentration of toxic metals in the incinerator residues, and where concentration spikes were detected, accurate real-time metal concentration measurements had the potential to provide feedback to clean-up systems, thereby minimising the overall environmental effect.