Research

Peracetic acid is a suitable disinfectant for recirculating fish-microalgae integrated multi-trophic aquaculture systems

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Abstract

tIntegrated multi-trophic aquaculture (IMTA) is a promising direction for the sustainable developmentof aquaculture. Microalgae have good potential to be integrated with recirculating aquaculture sys-tems because they can use the nitrogen excreted from fish and share the same optimal pH value asin aquaculture. As a byproduct, the microalgae biomass can be used for fish feed or biofuel. How-ever, the recirculating fish-microalgae IMTA system is under constant threat from fish pathogens andphytoplankton-lytic bacteria. Therefore, it is necessary to apply proper disinfectants as prophylaxis ortreatment which are effective against these threats, but safe to fish and microalgae. For this purpose,peracetic acid (PAA) is a valid option because it is highly effective against fish pathogens and bacteria atlow concentrations and degrades spontaneously to harmless residues. In the present study, we exposedthe culture of a marine microalgae Tetraselmis chuii once per day for four days to four PAA productswith differing hydrogen peroxide (H2O2)/PAA proportions at two concentrations (1 and 2 mg L−1PAA).The H2O2solutions at equivalent total peroxide (H2O2+ PAA) concentrations were tested in parallel. Theresults show that the growth and photosynthesis of T. chuii were not affected by three of the PAA prod-ucts (Wofasteril®E400, Wofasteril®E250 and Applichem®150) and equivalent H2O2solutions at bothconcentrations. In contrast, Wofasteril®Lspez and an equivalent H2O2solution at both concentrationscaused irreversible culture collapse, photosynthesis dysfunction and irreversible cell damage. In con-clusion, PAA products with low proportions of H2O2are optimal disinfectants for fish-microalgae IMTAsystems.