Evaluation of Arthrospira (Spirulina) platensis growth on cheese whey in the context of circular economy

Cultivation of microalgae using wastewater could be considered as a cost-effective treatment method, while providing the necessary nutrients to for the production of high-value biomass. The potential use of cheese whey for Arthrospira (spirulina) platensis cultivation could provide a sustainable solution aligned with circular economy principles for the treatment of dairy industry wastewater, in regions such as North Aegean (Greece). The aim of this research is to investigate the parameters that influence the growth of Arthrospira platensis biomass on whey rich solutions, as a substitute to chemical nutrient feeds, according to the practices of circular economy and sustainable development. Specifically, the effect of different whey dilution ratios and irradiation conditions on biomass productivity, nutrient consumption and COD removal were examined in batch experiments. Results show that the concentration of 10% (v/v) cheese whey exhibited the best performance in both experimental illumination sets; continuous and light/dark cycles. The highest biomass production (1.06 g l-1) was achieved in 14-day experiments at a pH 10.5 and with a photoperiod of 12 h dark/light. In the culture with light/dark cycle, approximately 85% COD removal and 70% NO-3 - N consumption were measured. Overall, Arthrospira platensis cultures demonstrate a consistent growth performance in a wide range of conditions and can be considered as an efficient method of treating cheese whey wastewater. Concurrently, Arthrospira biomass production presents interest, due to the low cost associated with the unsterile nature of the cheese whey waste and the utilization of the whey waste as a nutrient for growth.