API TR 1155-2-2016 pdf free download

API TR 1155-2-2016 pdf free download.Shoreline In Situ Treatment (Sediment Mixing and Relocation) Fact Sheet.
Oil and Particle Interaction The formation of Oil Particle Aggregates (OPAs) is a natural process in which fine particles interact on available oil surfaces. 2 This process was described in the 1970s, but its full significance in the break-down of oil in the natural environment was not appreciated until 1990 during the Exxon Valdez response. 3 The OPA process has since been verified by dozens of laboratory studies 4 and a major multi-nation field experiment in Norway in 1997 5 . OPA formation is a significant weathering process because the result is a rapid increase in the surface area of the oil that is available for natural dispersion, biodegradation, and photo-oxidation. OPA Formation OPA is an emulsion that forms naturally due to the electrostatic attraction between oil and mineral or organic particles when they mix. Aggregates of oil and fine particles can form naturally where suspended particulate matter (SPM), clays, or other fine particles are present. When particles attach to an oil droplet, they prevent the droplet from coalescing with other oil droplets 2 , therefore promoting the formation of stable oil droplets. OPA formation also prevents the adhesion of oil to surface sediments. Because OPAs are not as “sticky” as oil alone, the oil-water contact area is greatly increased when OPAs form, therefore enhancing both oil dispersion into the water body and oil biodegradation 6 . OPA Representation The following figures illustrate typical OPA structures. The figure below is a schematic representation of oil droplets broken up by the attachment of fine particles, causing an increase in surface area. The photograph on the right is a microscopic image (with schematic representation below) of one aggregate of oil droplets with mineral particles that detached from a large layer of oil.
OPA Requirements The formation of OPA requires: ® The presence of oil with polar components · Polar compounds are found in most crudes and fuel oils · Polar compounds are not typically found in highly refined products ® An oil viscosity sufficiently low to allow droplet formation and subsequent aggregation 8 · Low viscosity oil takes seconds to form OPA · Highly viscous oil may require days to form OPA · Extremely viscous and solid oils such as asphalt pavement may not form OPA ® The presence of water with sufficient ionic strength · Readily occurs in both marine and estuarine/brackish environments, where salinity plays a key role in OPA formation · Also occurs in freshwater environments 9 , where calcite and quartz play a role in OPA formation 10 ® The presence of fine mineral or organic particles · Fine particles are naturally present in most of the world’s water bodies · The finer the particle, the larger the surface area, which accelerates OPA formation · The finer the particle, the higher the charge, which increases the attraction to the oil droplets Fate of OPA ® When an OPA is formed, the surface area-to-volume ratio of the oil is increased by orders of magnitude, accelerating and enhancing the weathering processes of evaporation, dissolution, dispersion, and ultimately biodegradation and photo-oxidation. ® The particles within the aggregates act as a surfactant, increasing the stability of the oil droplets, and preventing the oil from re-coalescing into larger droplets or oil slicks. ® Aggregation increases the specific density of the coated droplets, which removes oil from the water surface. However, the aggregates are usually less dense than the particles, and therefore remain in suspension longer and are dispersed farther than un-oiled sediments 11 . ® The ultimate fate of OPA is the biodegradation, or (to a lesser degree) photo-oxidation of the exposed oil at the particle surface, converting the oil to carbon dioxide and water.