Toxic air emissions from biomass combustion

Wood industries and power plants generate enormous quantities of wood ash. Toxic air emissions during biomass combustion are typically very low and often near or below detection limits. During the combustion of wood, the basic cations are transformed to their oxides, which are slowly hydrated and subsequently carbonated under atmospheric conditions. Char and ash samples from biomass combustion were analyzed by atomic absorption spectrophotometrically for their toxic metal elements: arsenic, cadmium, chromium, copper, lead, and mercury. Maximum levels of the metals were 4.12 mg/kg, 1.06 mg/kg, 4.58 mg/kg, 42.7 mg/kg, 3.83 mg/kg, and 0.126 mg/kg, respectively, in the ash samples.