In this study, we conducted proof-of-concept research towards the simultaneous treatment of livestock wastewater and the generation of high-quality biodiesel, through microalgae technology. Both original (OPE) and anaerobically-digested (DPE) piggery effluents were investigated for the culture of the microalgae, Desmodesmus sp. EJ8-10. After 14 days’ cultivation, the dry biomass from microalgae cultivated in OPE increased from an initial value of 0.01 g/L to 0.33–0.39 g/L, while those growing in DPE only achieved a final dried mass of 0.15–0.35 g/L, under similar initial ammonium nitrogen (NH4+-N) concentrations. The significantly higher microalgal biomass production achieved in the OPE medium may have been supported by the abundance of both macronutrient, such as phosphorus (P), and of micronutrients, such as trace elements, present in the OPE, which may not been present in similar quantities in the DPE. However, a higher lipid content was observed (19.4–28%) in microalgal cells from DPE cultures than those (18.7–22.3%) from OPE cultures. Moreover, the fatty acid compositions in the microalgae cultured in DPE contained high levels of monounsaturated fatty acids (MUFAs) and total C16–C18 acids, which would afford a superior potential for high-quality biodiesel production. The N/P ratio (15.4:1) in OPE was much closer to that indicated by previous studies to be the most suitable (16:1) for microalgae growth, when compared with that determined from the DPE culture medium. This may facilitate protein synthesis in the algal cells and induce a lower accumulation of lipids. Based on these findings, we proposed a new flowsheet for sustainable livestock waste management. Display omitted •Microalgal biomass growth was hindered in digested piggery effluent (DPE) culture.•Microalgae removed >90% of N and P from both DPE and original piggery effluent (OPE).•DPE could increase the lipid content and productivity from microalgae.•Microalgae cultured in DPE had better quality biofuel potential than that from OPE.•A new flowsheet was proposed for livestock waste treatment and biofuel recovery.