Livestock farming generates large volumes of nutrient-rich manure, posing environmental challenges such as ammonia emissions and nutrient leaching. Addressing these issues through nutrient recovery offers a sustainable solution aligned with circular economy principles. In this study, two types of biofilm reactors—a membrane-aerated biofilm reactor (MABR) and a moving bed biofilm reactor (MBBR)—were evaluated for their capacity to convert ammonium in dairy slurry into a water-soluble, nitrate-based liquid fertilizer suitable for hydroponic use.

The reactors were operated under continuous conditions, with stepwise increases in influent ammonium concentration to assess system resilience. While MBBR performance declined at higher loading rates, the MABR consistently maintained >90% ammonium removal, demonstrating superior operational stability. The MABR’s enhanced oxygen transfer capability, provided by gas-permeable membranes, along with a high surface area for biofilm attachment, enabled effective nitrification and nitrate recovery. This work highlights a scalable, energy-efficient solution for transforming livestock waste into value-added fertilizer products, supporting innovation in sustainable nutrient management and contributing to the circular bioeconomy.