Lactic acid production from filamentous algae grown using aquaponics wastewater

Abstract

Food production from aquaponics can produce much nutrient-rich wastewater that otherwise might be recovered in productive processes for sustainable practices. Algae cultivation for nutrient recovery from incidental waste streams in aquaculture production provides an opportunity for valuable materials recovery from such processes. The purpose of this work was to investigate the use of green filamentous algae grown from aquaculture wastewater as a feedstock for lactic acid fermentation. Filamentous green algae community was grown on tilapia aquaculture wastewater under a range of nutrient dilutions in floway reactor systems, with repeated periodic harvest resulting in algal biomass recovery. Algae biomass yields resulting in a mean ash free dry weight productivity of 7 g m⁻² d⁻¹ were observed. Lactic acid fermentation of this biomass was performed under variations of process amendments, resulting in a peak lactic acid concentration of 20 g L⁻¹ and a yield of 80 % lactic acid from the available sugars. These amounts were comparable to yields obtained from LA fermentation of cucumber waste biomass derived from the same aquaponics system. As such, filamentous algae for lactic acid fermentation were found to be a promising approach for mass and nutrient recovery in aquaponics production systems.