Bio-based mineral fertilizers from agricultural waste via ammonia scrubbing

Bio-based ammonium sulfate and ammonium nitrate fertilizers produced from agricultural waste via (stripping-)scrubbing technology show comparable performance to synthetic N fertilizers in lettuce and maize trials. Recovered from animal manure, these fertilizers contain 3–9% N (AS) and 13–20% N (AN), with no significant differences in crop yield, nutrient uptake, or nitrate leaching risk. Field and pot experiments on loamy-sand and sandy-loam soils in Belgium confirm their agronomic viability. Despite regulatory challenges due to nitrogen concentrations below the current EU threshold of 15%, proposed reductions to 1.5–3% may support their classification as fertilizers. The technology achieves 70–99% ammonia recovery efficiency across three pathways: air cleaning, recirculation, and end-of-pipe treatment. Results indicate AS and AN can effectively replace synthetic fertilizers in short-term cultivation, though long-term impacts require further study.