Effect of Aureococcus anophagefferens biomass on its inactivation by hydrogen peroxide: culture study and empirical modeling

Hydrogen peroxide (H₂O₂) has been shown effective in selectively removing brown tide algal bloom caused by the pelagophyte Aureococcus anophagefferens. This paper uses culture studies and a modeling approach to examine the inactivation of A. anophagefferens by H₂O₂. Specifically, the effects of the initial cell density of A. anophagefferens on the decomposition of the externally added H₂O₂ and the inactivation of the alga were evaluated. In the presence of A. anophagefferens at an initial cell density of 0.04–1.5?×?10⁶ cells mL^?1, 70–98 % of the externally added 1.6 mg L^?1 H₂O₂ was decomposed within 24 h, and the rate of H₂O₂ decomposition increased with increasing cell density. When the initial cell density (B ₀) was 0.09–1.5?×?10⁶ cells mL^?1, the initial H₂O₂ addition (C ₀) was 0.8–1.6 mg L^?1, and the contact time (t) was less than 24 h, the inactivation of A. anophagefferens followed an empirical model: ln(IVF _t ?/?IVF₀)?=??0.014ln(B ₀)C ₀ ^0.583 t ^1.006, where IVF _t ?/?IVF₀ is the inactivation efficiency and is the ratio of the alga's in vivo chlorophyll fluorescence at time t and time zero. This model predicts a narrow range of H₂O₂ dosage of 0.9?2.1 mg L^?1, which is capable of effectively inactivating A. anophagefferens of category 3 bloom density (0.2–1.5?×?10⁶ cells mL^?1) within 8–24 h. Overall, the empirical model provides an initial description of the inactivation of A. anophagefferens by H₂O₂ as a function of cell density, dosage, and time.