Manure processing as energy efficient fertilizer production technology

Abstract Modern agriculture relies on nitrogen fertilizers produced through the energy-intensive Haber–Bosch process. This industrial ammonia synthesis process demands a significant amount of energy (41 GJ/1000 kg of nitrogen) and contributes to greenhouse gas emissions (1920 kg of carbon dioxide when natural gas is used). While, efforts have been made to shift towards renewable energy sources for nitrogen fixation, fossil fuels remain the primary energy source. In contrast, meat production generates substantial amounts of manure containing nitrogen compounds. The utilization of manure-derived fertilization offers potential for a circular economy. However, in regions with intensive animal production, alternative forms of manure utilization may be necessary. Manure fertilization is challenging due to transport and application energy demand, environmental pollution and health risks, making it less convenient compared to mineral fertilizers. Manure application consumes up to 63% of energy required for synthesis and application of equivalent urea fertilizer. This article aims to address the critical issues related to manure fertilization and explores potential technological solutions for nitrogen recovery, with a focus on energy consumption. Our results suggest that implementation of nitrogen recovery technology significantly (more than 50% in comparison to manure) reduces energy demand for fertilizer application and transport. The lowest general fertilizer handling cost was achieved for struvite precipitation, followed by stripping and reversed osmosis concentration. By recovering nitrogen from manure and converting it into usable fertilizers, we can significantly reduce energy consumption and mitigate the environmental impact of traditional nitrogen fertilizers. Graphical abstract