Development of efficient precipitator composed of baked shell

Abstract

  With the aim of utilizing the oyster shells which are generally discarded in shell culture, we have developed an efficient precipitator to clarify muddy water from a baked oyster shell.
   We examined the effect of baking temperature (200℃, 300℃, 400℃, 500℃, and 600℃) on the effect of precipitation and found that 400℃ was the most effective baking temperature to produce a precipitator. The efficiency of precipitation was evaluated as the precipitation ability of the baked shell in muddy water containing kaolin. Precipitators made of shell baked at temperatures below 300℃ were more efficient under slow stirring conditions, while those baked at temperatures above 500℃ were more effective under fast stirring conditions. Precipitators made of shell baked at 400℃ were effective under both stirring conditions. The specific surface area and grain size of the shell reduced with the increase in baking temperature. This is possibly because 400℃ is a suitable baking temperature for both generating the small grain size that is effective for flock formation and realizing a large specific surface area necessary for the physical strength of the flock.