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.
Many of the aerobic treatment systems described in other sections of this report utilize anoxic or anaerobic stages to accomplish specific treatment objectives. Anaerobic treatment processes are typically used for the treatment of waste that has a high concentration of biodegradable organic material.he primarily use of this technology is for the removal of nitrogen from wastewater. Description of process Nitrified process water flows into the anoxic reactor and is combined with a supplemental carbon source, typically a dilute methanol solution.