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San Joaquin County Community Diesel Engine Emission Control Technologies <br /> Development Department <br /> An additive added to diesel fuel in order to aid in soot removal in diesel <br /> particulate filters by decreasing the ignition temperature of the carbonaceous <br /> exhaust is called a fuel home catalyst(FBC). These can be used in conjunction <br /> with both passive and active filter systems. As noted in the body of the report, <br /> FBC can improve fuel economy, aid other system's performance, aid other <br /> retrofit systems, and decrease mass PM emissions. FBC/diesel particulate filters <br /> systems are in wide spread use in Europe in both on-road and off-road,mobile <br /> and stationary applications(DieselNet 2000.02b). <br /> The following sections describe properties of some of the more common — <br /> additives that staff has encountered in its research. <br /> Cerium based additives <br /> Description: When used with appropriate filters,regeneration tends to be <br /> smooth,high local peak temperatures inside the trap do not occur and engine <br /> backpressure remains approximately constant. Typical concentrations for <br /> Cerium additives can range from around 20 ppm up to 100 ppm. However, at the <br /> highest concentrations,there can be some problems with backpressure increases <br /> and filter plugging depending on the system and application. Lower level cerium <br /> additives tend to avoid this problem provided that periodic trap regeneration <br /> occurs. There is evidence supporting the increase of nano-particulate matter <br /> (Mayer 2002). This is related to additive concentration with appreciable <br /> increases in nano-particulate formation with higher additive concentrations. For _ <br /> instance, 100 ppm cerium reduces the balance temperature of a trap system from <br /> 537-557 °C to 432 °C. Used in conjunction with a filter,PM mass emissions are <br /> reduced from 70 to 98 percent and NOx is either unchanged or reduced. Use of <br /> cerium additives can increase fuel consumption by 4.7 percent in some <br /> circumstances (DieselNet 2000.02b;Mayer 1999; Mayer 1998; Lemaire 1999; <br /> HEI,Attachment A;Mayer April 1998). <br /> Current Use: Cerium based additives are in wide spread use in Europe and <br /> VERT approved when used with DPFs. A cerium based additive is part of <br /> Peugeot's new filter based system and, in addition to on-road applications, <br /> cerium additives are used off-road in construction and forklift applications <br /> (Mayer 2002;Lemaire 1999). <br /> Environmental Fate and Transport: Crops can take up cerium. Cerium has <br /> affinity for humic substances that may alter its availability in aquatic systems. <br /> Current fate and transport studies are limited and may not adequately address v <br /> long term environmental exposure risks to both humans and other organisms <br /> (Molycorp Inc. 1995,HEI Communication 9 2001). <br /> Health Risks: Although cerium has low acute toxicity, long term health and <br /> environmental effects are less well understood. Inhalation is thought to be the <br /> primary method of expose to cerium from diesel exhaust. However, other routes <br /> of entry might include direct contact with the additives and ingestion. The form <br /> cerium takes can also influence its biological and environmental fate. Cerium <br /> DeSilva Gates Quarry Project <br /> Draft Environmental Impact Report L-6 <br /> As 05105.05 <br />