Transforming waste management: Converting pig slurry into clean energy and biomass through integrated MFC-microalgae systems

Microbial Fuel Cells are emerging as one of the most promising technologies for simultaneous energy generation and wastewater treatment. At the same time, producing microalgae using wastewater as a growth medium has attracted scientific interest due to its potential to produce valuable products. This study presents a novel integrated system combining Microbial Fuel Cells with a Microalgae-Bacteria consortia to treat pig slurry, while simultaneously generating electrical energy and producing valuable biomass. First, Microbial Fuel Cells incorporating an ionic liquid-based membrane ([N 8 – 10,8-10,8-10,1 + ][Cl − ]) were evaluated as a cost-effective and durable alternative to conventional membranes based on per - and polyfluoroalkyl substances. This approach resulted in significant reductions in COD and BOD, while generating a voltage of 550 mV and a power density of 153 mW·m −2 . In the second phase, the treated pig slurry was used as a growth medium for microalgae-bacteria. Different concentrations of pre-treated pig slurry (10 %, 20 %, and 30 %) were tested for their effectiveness in nutrient recovery and biomass production. Notably, 100 % of N-NH 4 + and over 60 % of P-PO 4 3− were recovered, with biomass productivity and cell density comparable to the control using chemical fertilizers. This combined system shows strong potential for sustainable pig slurry management, renewable energy generation, and biomass production. • MFCs based on IL membranes treat pig slurry while generating 550 mV and 153 mW·m −2 . • MFC-MB system recovers 100 % N-NH 4 + , 50 % COD and over 60 % of P-PO 4 3− . • Using MFC-treated pig slurry obtains equal biomass productivity than fertilizers. • Integrated MFC and MB treatment is a sustainable approach for pig slurry management.