LONG TERM EXPERIENCES IN USING MICROALGAE IN WASTEWATER TREATMENT UNDER SUBOPTIMAL CLIMATIC CONDITIONS

Environmental deterioration, resource depletion and climate change are forcing the water industry to find cost-effective and low-energy solutions able to remove pollutants while recovering most of the resources contained in wastewater. In such challenge, microalgae-based technologies are promising as they rely on phototrophic microorganisms which remove nutrients (nitrogen and phosphorus) by assimilation, supply oxygen for the aerobic bacteria, therefore decreasing the energy demand of the plant and fix CO2 which could be provided by flue gases. Also, the microalgal biomass can be used for the recovery of resources such as energy, biofertilizers, feed, biopolymers, pigment, etc. In this study, a comprehensive evaluation of microalgal applications integrated into conventional engineered technologies such as municipal and agro-industrial wastewater treatment and biogas production is presented. Data were gathered during several projects (MICROGATE, IMAP, Polo delle MICROALGHE) with the aims of designing, implementing, and operating different configurations of microalgal based systems. The bioreactor park included bench (up to 1 L), laboratory (up to 10 L) and pilot scale raceway ponds (4-6 m2) and bubble columns (70 L). Their performance and efficiency were determined and monitored using a multidisciplinary approach consisting of well-established analytical methods, innovative tools assessing the photosynthetic efficiency, tailored respirometry protocols and advanced molecular methods. The biomass obtained was then chemically and microbiologically characterized for the definition of the best valorization pathway. Finally, all the information obtained were used for the development of mathematical models.