Sustainable recovery from pig slurry using ionic liquid microbial fuel cells and microalgae consortia

Pig slurry management has emerged as a pressing environmental challenge in the context of rapid population growth and intensified livestock production, highlighting the need for sustainable recovery technologies. While microalgae-bacteria (MB) systems offer promising opportunities for nutrient recycling, the high turbidity of raw pig slurry (PS) typically limits their direct application. This study proposes an innovative two-step treatment that combines microbial fuel cells (MFCs) with MB consortia to enhance both pollutant removal and resource recovery from raw PS with COD levels exceeding 18,000 mg·L⁻¹. Unlike conventional designs relying on perfluorinated membranes, the MFCs employed an ionic liquid [N_{8-10,8-10,8-10,1}⁺][Cl^-] as a proton exchange medium, achieving 50% of COD removal and generating 57.27 ± 10.99 mW·m⁻². The effluent was subsequently treated with MB consortia, yielding biomass productivities of 0.1 to 0.2 g·L⁻¹·day⁻¹, comparable to chemical fertilizer-based controls. Cell density with pre-treated and untreated pig slurry also matched control levels. In pollutant recovery, the combined microbial fuel cell and microalgae-bacteria treatment achieved up to 67% recovery of COD, over 99% of N-NH₄⁺, and between 65 and 85% of P-PO₄^3-. These findings highlight the potential of integrating MFCs with MB consortia as a strategy for raw pig slurry management, t-ransforming waste into renewable energy and bioresources. KEY POINTS: • Pig slurry is transformed into biomass and bioenergy using sustainable technologies • Microalgae-bacteria consortia enhance nutrient recovery and water treatment • Ionic liquid microbial fuel cells support energy generation and COD reduction.