Journal Article
Advancing Circular Economy through Microalgae-Based Wastewater Treatment: Life Cycle Assessment of Industrial Nutrient Valorization in Northern Greece
Maria Batsioula; Georgios Archimidis Tsalidis; Chrysa Anagnostopoulou; Ioannis Papachristou; Panagiotis G. Kougias; Xenofon Spiliotis; George F. Banias
Circular Economy and Sustainability · Vol. 6, Issue 3 · 2026
Abstract
Microalgae cultivation offers promising opportunities for wastewater bioremediation and the production of high-value bio-based products; however, the environmental sustainability of existing technologies remains under evaluation. This study presents a cradle-to-gate life cycle assessment of a lab-scale Chlorella vulgaris cultivation system in Northern Greece using food industry wastewater, operated in a 5 L photobioreactor. Primary data were assessed using the ReCiPe 2016 Midpoint (H) method across 17 impact categories, with a functional unit of 1 kg dry-weight biomass. The cultivation stage was the main environmental hotspot, contributing 63% of Global Warming Potential (135 kg CO₂ eq.), and over 50% of impacts across most of the selected categories, driven mainly by electricity demand for continues artificial lighting. Compared to a reference system using urban wastewater, cultivation in industrial wastewater showed lower impacts in 12 of 17 impacts categories, due to its nutrient-rich medium. Compared to clean-water cultivation with synthetic nutrients, the analyzed system performed better in 16 of 17 categories. A scale-up sensitivity analysis demonstrated that replacing continuous artificial lighting with industrial-scale lighting strategies reduces cultivation-stage Global Warming Potential by up to 96%, confirming that the system’s high energy intensity reflects its operational scale rather than a characteristic of the technology. The system demonstrates potential for decentralized wastewater management, supporting the EU Wastewater Treatment Directive. Its integration with industrial wastewater valorization represents a circular nutrient-reuse approach aligned with industrial symbiosis and circular bioeconomy principles. Addressing a gap in the Greek context, this work provides a benchmark for sustainable practices in the Mediterranean region.