Ozone's effects on power-law particle size distribution in recirculating aquaculture systems

A power law model for particle size distributions has been applied by several researchers to aquacultural and aquatic systems Rueter and Johnson [Aquacult. Eng. 14 (1995) 123] demonstrated that ozonation of trout hatchery water increased the proportion of large particles in the water. Summerfelt et al. [Aquaculture 158 (1997) 57] speculated that this increase in particle size led to their observed improvement in screen filter performance in a recirculating aquaculture system. While ozonation increases the relative abundance of larger particles, these particles are continuously removed by clarifiers in recirculating systems. This project examines the effect of ozonation on the particle size distribution remaining in the system at steady state conditions. In these experiments, the power law modeled the particle size distribution data very well for the majority of trials. Surprisingly, regardless of ozone dose, there was no significant difference in the slope of the power law fit for the particle size distribution. In over one-half of the experimental trials when no ozone was added, the particle size distributions were distinctly bimodal. The power law model for particle size distribution did not fit these data very well. When the power law did not fit the data, 50% of particles were smaller than 14 μm, and the turbidities measured in the production tank were significantly higher than when the particle distribution obeyed the power law.