Microalgae technology for polishing chemically-treated fish processing wastewater

Abstract

The development of cost-effective treatment methods for nutrient-rich effluents is of great importance. In this study, microalgal-based technology was investigated as a final polishing stage for fish processing wastewater (FPWW) after fat and oil removal, with the purpose of facilitating wastewater reuse and nutrient recovery. First, the effect of FPWW filtration on the growth of two microalgal species (Chlorella sorokiniana and Selenastrum sp.) was investigated under batch mode. For both microalgae, the final biomass concentration and nutrient removal levels were higher in unfiltered FPWW than in filtered FPWW. Chlorella sorokiniana growth was notably greater than that of Selenastrum sp. Chlorella sorokiniana was further cultivated in a semi-continuous mode, which lead to stable microalgae growth and high nutrient uptake in unfiltered wastewater with no need to eliminate indigenous microorganisms and contamination. However, based on biochemical analysis, filtration increased the availability of essential fatty acids and carotenoids from Chlorella sorokiniana, thus increasing the commercial value of the algal biomass.