Mercury emission from sewage sludge incineration in Japan

Sewage sludge contains trace amounts of mercury, and sewage sludge incineration is a major source of mercury emissions. However, relatively few studies have reported on mercury emissions from sewage sludge incineration. Consequently, data on emissions from sewage sludge incinerators must be updated to estimate current emissions of mercury. In this study, we examined mercury emissions and speciation using continuous mercury analyzers in two incinerators. The mercury concentrations in stack gas from facilities A and B were 36.6 and 21.1 μg/Nm³, respectively. As a result, the emission rate was calculated to be 0.282–0.750 g/ton-dry sludge. Considering the total amount of sewage sludge incinerated in Japan, the mercury emissions from sewage sludge incinerators were estimated to be 0.49–1.31 tons/year.