Combination of solar disinfection (SODIS) with H2O2 for enhanced disinfection of marine aquaculture effluents

Abstract Technologically advanced recirculation aquaculture systems (RAS), developed for intensive farming, allows to recycle about 90–99% of water. As a result, accumulation of pathogenic bacteria in water often occurs and possesses threat of infectious fish diseases. The goal of this study was to evaluate feasibility of solar disinfection in combination with hydrogen peroxide for seawater and real marine aquaculture effluent. Specific roles of solar disinfection (SODIS), hydrogen peroxide and highly reactive oxidizing species (experiments conducted in presence of tert-butyl alcohol), generated in combined SODIS/H 2 O 2 process were investigated. Natural consortia of Vibrio spp., known as highly resistant pathogen, present in seawater and real marine aquaculture effluent were chosen as target microorganisms. The SODIS/H 2 O 2 process significantly enhances inactivation of natural Vibrio consortia ( Vibrio harveyi, Vibrio owensii and Vibrio alfacsensis ) in seawater in comparison with individual SODIS and H 2 O 2 treatment. The best results in terms of Vibrio spp. inactivation efficiency was obtained with SODIS/H 2 O 2 conducted using open channel raceway reactor. The efficiency of Vibrio spp. inactivation by SODIS/H 2 O 2 in raceway and compound parabolic collector (CPC) reactors was found to be similar, requiring the dose of 28–29 Wh m −2 for complete inactivation of Vibrio spp. present in seawater. Absence of toxic effect of residual H 2 O 2 for Nannochloropsis gaditana, as well as absence of Vibrio spp. regrowth (48 h) indicate suitability of SODIS/H 2 O 2 process for inactivation of pathogenic bacteria in aquaculture effluent and following nutrients removal by microalgae. Moreover, feasibility of SODIS/H 2 O 2 performed in raceway reactor for disinfection of real aquaculture effluent, containing more than 5⋅10 3  CFU mL −1 of Vibrio harveyi , was demonstrated requiring the dose of 34.4 Wh m −2 for complete Vibrio spp. inactivation. The annual operation and maintenance cost of aquaculture effluent disinfection using CPC and raceway reactors were evaluated.