Particulate emission reduction from road bitumen fumes by a novel process combining plasma treatment and filtration

The processes involving heated bitumen generate fumes containing particles constituted mainly of various organic materials like polycyclic aromatic hydrocarbons (PAHs), some of them are carcinogenic. A new process combining plasma post- discharge treatment and bed filtration has been proposed to treat bitumen fumes. Experiments were conducted at a semi-industrial scale with a pilot unit capable to treat 200 m 3/h. Fumes were generated by heating a continuously stirred batch of bitumen at 170°C and diluted with air at 20°C. The results showed that the average number median diameter was increased when the fumes were treated in the plasma post-discharge zone. As a result, the trapping efficiency on glass filters was increased by 75%. GC-MS analyses of the soluble fraction have shown that new compounds characterized by a high chemical polarity and a low volatility were produced by the reaction between the active species created by the discharge and the bitumen fumes. Thus, the increase of particle size could result of condensation taking place on the particles surface or aggregation mechanisms between particles.