Acid-tolerant microalgae-based winery wastewater treatment: performance evaluation and techno-economic analysis

This study evaluates the potential of two acid-tolerant microalgal strains, Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3, for winery wastewater treatment (WWT) by including laboratory- and pilot-scale investigations, and techno-economic analysis (TEA). Laboratory experiments revealed significant growth in strain MAS1, especially in photobioreactors (PBRs), outpacing strain MAS3 with >125 % increase in biomass after four days. Both the strains showed lower but consistent growth in aquaria whereas biomass production was significantly higher in PBR. Nutrient removal in PBR was superior for organic carbon while it varied for nitrogen and phosphates, indicating system-specific advantages. Transitioning to pilot-scale high-rate algal pond with semi-continuous operations showcased higher growth rates in strain MAS1, achieving 1110 mg L^-1 biomass yields and improved specific nutrient removal rates for organic carbon, nitrogen, and phosphates as compared to strain MAS3. When considered three processing capacities of 10, 50, and 100 m³ over 15 years, TEA revealed a positive net present value and internal rate of return based on the revenue generated from biomass, thus confirming the economic viability of microalgae-based WWT. Our study highlights the potential of microalgal systems for sustainable wastewater management, stressing the importance of system design and scaling for environmental and economic efficiency.