Extraction of Liquid Fertiliser from Urine Using Microbial Fuel Cells: A Sustainable Solution for Hydroponics in Circular Cities

For a circular economy, sustainable reuse and recycling of resources are vital strategies. This study builds on proof-of-concept research demonstrating the transformation of urine into treated filtrate containing NPK nutrients, water, and energy. It assesses the suitability of catholyte, produced by electro-filtrating microbial fuel cells (EF-MFCs), for hydroponic plant cultivation. The results showed that the MFC reactor recovered nutrients such as potassium, phosphorus and nitrogen in the form of liquid (catholyte) in previously empty chamber and simultaneously produced electrical energy (1.5-2 mW) from synthetic urine. Catholyte mixed in varying proportions with standard nutrient solution and used neat was evaluated for basil growth, wet, and dry biomass. Results showed a 60/40 nutrient solution-to-catholyte mix was most effective, highlighting EF-MFCs' potential for sustainable agricultural applications.