The Cultivation of Lipid-Rich Microalgae Biomass as Anaerobic Digestate Valorization Technology-A Pilot-Scale Study

The aim of the study was to determine the use of digestate from anaerobic digestion of dairy wastewater as a culture medium for microalgae to obtain bio-oil. The experiments were conducted at a small scale in a closed raceway pond. The efficiency of the microalgae biomass production, the digestate treatment efficiency as well as the content and properties of the bio-oil obtained from the microalgal cells were analyzed. The produced biomass concentration was about 3000 +/- 10.5 mg dry biomass/L, with an average growth rate of 160 +/- 6.6 mg(dm)/L.d. The efficiency of organic compound and nutrient removal was above 90%. The bio-oil content in the biomass was about 20%. Based on the results of the study, a concept for technical-scale technology was developed.