Contribution of Aftertreatment Technologies to Alleviating SOA and Toxicity Generation from Typical Diesel Engine-Emitted I/SVOCs

Characteristics of inland ship and the effect of combined diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) aftertreatment system on their pollutant emissions

Inland ships, often overlooked, are major sources of air pollution, especially near populated areas. This study aims to characterize emissions from inland ships and evaluate the effectiveness of Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) systems in reducing pollutants across various operational loads. Emission factors (EFs) of PM and CO2 in raw exhaust, untreated by DOC + DPF, increase with engine load, reaching 9.21 g kg-fuel-1 and 3060 g kg-fuel-1 at 75 % load, respectively. Conversely, the EFs of CO and volatile organic compounds (VOCs) in raw exhaust decreased with higher engine load, with averages of 12.7 ± 10.9 g kg-fuel-1 and 2.46 ± 1.52 g kg-fuel-1, respectively. Additionally, oxygenated VOCs (OVOCs) made up more than 43.3 ± 15.9 % of total VOCs, with formaldehyde and acetaldehyde being the most prevalent species, contributing 55.9-75.3 % of OVOCs. Ozone formation potential (OFP) was primarily driven by OVOCs, with EFs of 4.84 ± 5.44 g O3 kg-fuel-1 while secondary organic aerosol formation potential (SOAFP) was dominated by aromatics, with EFs of 0.742 ± 0.365 g SOA kg-fuel-1. The DOC + DPF installation reduced PM by 92.1 %, CO by 100 %, and VOCs by 84.1 % at the highest load. Additionally, they reduced OVOCs by 65.8 ± 6.62 % and aromatics by 74.9 ± 12.5 %, further lowering OFP and SOAFP. The NO conversion increased with engine load, but NO2 was generated, resulting in a low total NOx conversion efficiency of 11.7-13.2 %. This study highlights the effectiveness of DOC + DPF system at higher loads in reducing PM, CO, and VOC emissions from inland ships, providing insights for future air quality improvement and global studies on aftertreatment systems.