ABSTRACT Solids removal is very important for water quality maintenance in recirculating aquaculture systems (RAS). Ozonation is a practical water treatment which can promote the solids removal. However, the characteristics of ozonation effects on particles are still unclear. In this study, the effect of ozonation on particle size distribution (PSD) was investigated for seawater from a RAS of Pacific white shrimp (Litopenaeus Vannamei). Both flocculation and breakup of particles were demonstrated during ozonation treatment, which resulted in changes of PSD. By using a fractal characteristic value (Df), the flocculation process could be divided into three stages of preparation, growth and steady. Besides, the flocculation efficiency varied parabolically with contact time. A higher ozone dosage resulted in a shorter preparation stage, along with a longer growth stage (namely lasting a longer flocculation effect) and thus a relatively higher limit of parabolic flocculation efficiency. However, the limit would reach a peak and probably be accompanied with a more breakup of particles. The best flocculation efficiency was 43% at ozone dosage of 3.5 mg/L with 5 min contact time. Furthermore, a higher ozone dosage could produce more ammonia.

中文翻译：

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臭氧化对循环水养殖海水粒径分布的影响：颗粒絮凝和破碎分析

摘要 在循环水产养殖系统 (RAS) 中，固体去除对于维持水质非常重要。臭氧化是一种实用的水处理方法，可以促进固体去除。然而，臭氧对颗粒的影响特征尚不清楚。在这项研究中，对来自太平洋白虾（Litopenaeus Vannamei）的 RAS 海水的臭氧化对粒径分布 (PSD) 的影响进行了研究。在臭氧处理过程中，颗粒发生絮凝和破碎，导致 PSD 发生变化。通过使用分形特征值（Df），可以将絮凝过程分为准备、生长和稳定三个阶段。此外，絮凝效率随接触时间呈抛物线变化。较高的臭氧剂量导致较短的制备阶段，随着较长的生长阶段（即持续较长的絮凝效果），因此抛物线絮凝效率的限制相对较高。然而，这个极限会达到一个峰值，并且可能伴随着更多的粒子分裂。最佳絮凝效率为 43%，臭氧剂量为 3.5 mg/L，接触时间为 5 分钟。此外，更高的臭氧剂量会产生更多的氨。