Like our teeth, placoid scales have an inner core of pulp (made up of connective tissues, blood vessels, and nerves), which is covered by a layer of dentine (hard calcareous material). This dentine is covered by enamel-like vitrodentine.Scales in bony fish grow as the fish gets larger, but placoid scales stop growing after they reach a certain size, and then more scales are added as the fish grows.his dentine is covered by enamel-like vitrodentine. Scales in bony fish grow as the fish gets larger, but placoid scales stop growing after they reach a certain size, and then more scales are added as the fish grows.
Wet air oxidation is a promising technology for the treatment of refractory organic pollutants in the effluent from various industries in view of high pollutant removal efficiency at mild conditions and environmental friendliness not involving any harmful chemical reagent.
Soil vapor extraction, known as SVE, is the most frequently selected method for treatment of contaminated soil at superfund sites, brown-fields, refineries, gas stations, dry cleaners, and grain elevators.It is a relatively simple process that physically separates contaminants from soil.sed alone, soil vapor extraction cannot remove contaminants in the saturated zone of the subsurface, the water-soaked soil that lies below the water table. At sites where contamination is in the saturated zone, a process called air sparging may be used along with the SVE system.