Effect of biodiesel fuel on “real-world”, nonroad heavy duty diesel engine particulate matter emissions, composition and cytotoxicity

Abstract

Biodiesel is regarded by many as a "greener" alternative fuel to petroleum diesel with potentially lower health risk. However, recent studies examining biodiesel particulate matter (PM) characteristics and health effects are contradictive, and typically utilize PM generated by passenger car engines in laboratory settings. There is a critical need to analyze diesel and biodiesel PM generated in a "real-world" setting where heavy duty-diesel (HDD) engines and commercially purchased fuel are utilized. This study compares the mass concentrations, chemical composition and cytotoxicity of real-world PM from combustion of both petroleum diesel and a waste grease 20% biodiesel blend (B20) at a community recycling center operating HDD nonroad equipment. PM was analyzed for metals, elemental/organic carbon (EC/OC), polycyclic aromatic hydrocarbons (PAHs), and nitro-polycyclic aromatic hydrocarbons (N-PAHs). Cytotoxicity in a human lung epithelial cell line (BEAS-2B) following 24h exposure to the real-world particles was also evaluated. On average, higher concentrations for both EC and OC were measured in diesel PM. B20 PM contained significantly higher levels of Cu and Mo whereas diesel PM contained significantly higher concentrations of Pb. Principal component analysis determined Mo, Cu, and Ni were the metals with the greatest loading factor, suggesting a unique pattern related to the B20 fuel source. Total PAH concentration during diesel fuel use was 1.9 times higher than during B20 operations; however, total N-PAH concentration was 3.3 times higher during B20 use. Diesel PM cytotoxicity was 8.5 times higher than B20 PM (p<0.05) in a BEAS-2B cell line. This study contributes novel data on real-world, nonroad engine sources of metals, PAH and N-PAH species, comparing tailpipe PM vs. PM collected inside the equipment cabin. Results suggest PM generated from burning petroleum diesel in nonroad engines may be more harmful to human health, but the links between exposure, composition and toxicity are not straightforward.

Polycyclic Aromatic Hydrocarbons (PAHs) and nitrated analogs associated to particulate matter emission from a Euro V-SCR engine fuelled with diesel/biodiesel blends

“…What is more noticeable, however, is that the addition of 20% of biodiesel in the fuel mixture resulted in a decrease of 25% in PAHs emissions in the particle-phase for SCR-off and 32% for SCR-on. Similar results were found by previous studies (Turrio-Baldassarri et al, 2004;He et al, 2010;He, 2016;Yilmaz and Davis, 2016;Martin et al, 2017), however without test the simultaneous effect of biodiesel blends and SCR aftertreatment system. Our results concur with the findings of He et al (2010), who compared several studies, concluding that, on average, a reduction of 23% in PAHs emissions can be expected with a 20% addition of biodiesel to the fuel.…”

“…It seems therefore that only in the case of a combination of increased biodiesel additions and aftertreatment use, a reduction of Nitro-PAHs emissions was observed. This contrasts with Martin et al (2017) who found that B20 can reduce overall Nitro-PAHs concentrations in particle phase emissions in comparison to diesel, without aftertreatment.…”

“…Dibenzo [a,l]pyrene is considered as probably carcinogenic to humans (group 2A) and dibenzo [a,i]pyrene and dibenzo [a,h]pyrene as possibly carcinogenic to humans (group 2B) (IARC, 2018;Zielinska et al, 2004). When these compounds are associated with diesel/biodiesel blends exhaust particle-phase emissions, which are characterized by high concentrations of fine particulate matter (PM 2.5 ) (Guan et al, 2017;He, 2016), there is an intensification of many acute and chronic cardiopulmonary diseases, including asthma, respiratory system inflammation and lung cancer (Martin et al, 2017;HHS USA, 2004;Ravindra et al, 2008).…”

Effects of fuel components and combustion particle physicochemical properties on toxicological responses of lung cells

“…Differences in fuel can have a significant effect on cdPM properties, including size distribution, surface area, ability to generate reactive oxygen species, and volatile content. [10–13]…”

Road Testings and Evaluations for Waste Collection Vehicles Fueled with Biodiesel

“…Chemically speaking, biodiesel is referred to lower methyl esters of long chain fatty acids, synthesized by transesterification with lower alcohols or by esterification of fatty acids. Partially due to its diversity in feedstocks of the production and scales of plant, however, biodiesel in nature has a wide spectrum in its fuel quality [8][9]. The parameters that define the quality of biodiesel can be divided into two groups.…”