Reduction of toxic pollutants emitted from heavy-duty diesel vehicles by deploying diesel particulate filters

Abstract

In this study, the emission characteristics of PCDD/Fs, PCBs and PBDEs from heavy-duty diesel vehicles, and the reduction of these above toxic pollutants by deploying three kinds of diesel particulate filters (DPFs), that is, mobile metal filter plus catalyzed diesel particulate filter (MMF + CDPF), diesel oxidation catalysts (DOC) + CDPF and partial diesel particulate filter (PDPF) were investigated. The tested vehicles were maintained at 60 km/h for 10 minutes on a standard chassis dynamometer. The results show that vehicles with greater mileage had higher PCDD/Fs, PCB and PBDE concentrations in the exhaust. After the tested vehicles were equipped with DPFs, some trials showed the formation of PCDD/Fs and PCBs occurring inside the DPF. This could be due to the de novo and precursor formation resulting from the combined effects of the accumulated particulate in the DPFs, favorable temperature and longer retention time for the exhaust. The PDPF exhibited the largest reduction in these toxic pollutants emitted from HDDVs, which reached 83.9%-95.3% on mass basis, and 54.2%-71.9% on toxicity basis. However, significant differences existed among the trials of these three DPFs, revealing that the influential factors for the reduction of these toxic pollutants could be more complex than those for reduction of particulate matter. © Taiwan Association for Aerosol Research.