Spridning av släckvattenpartiklar : En studie på spridning av partiklar genererade från brand

Sammanfattning: During a fire large amounts of particles and unhealthy agents occur.  Polyaromatic hydrocarbons (PAH) and toxic metals are examples among many others. These agents have a capacity to bond to particles and when the fire is extinguished, the particles can be transferred with the extinguish water into the soil and to the groundwater. Recent studies in particles have been conducted. A study by Ulrika Iverfelt (2014) reviled that the particles from a fire contained large amounts of both PAH and metals, which is consistent with earlier analyses. Her column experiments with particles in the size ≤ 11 microns and ≤100 microns in silica sand, reviled that the larger particles was immobilized because the transportation was influenced by sieving or physiochemical particle and surface interactions. The transport of the particles in soil and groundwater is regulated by two main mechanisms: physiochemical surface interactions and straining. The particle size and the surface charge are examples of properties that affect the transport. The particle charge is described by the zeta potential, which is an important characteristic for surface interactions with the solid medium. The zeta potential depends on the water chemistry which varies in different extinguish water. The zeta potential was measured to be negative in Iverfelts (2014) study. In order to predict and understand the transport of the particles, more column experiments with different properties were requested. In this study several transport experiments where made. The four parameters: grain size, particle size, ionic strength and pH were investigated systematically. The same type of column, sand and source of extinguish water as in Iverfelts study was used.  The results from the study indicated that the smaller particles were not affected by sieving, as the larger particles. When the pH was lowered, the results indicated that some of the smaller particles, ≤11 microns were immobilized. This was probably because the zeta potential of the particles was reduced, which allowed the physiochemical particle and surface interactions.