Life cycle assessment of ammonia and methane emission reduction technology model for manure management in Hebei Province

Contemporary management of livestock manure faces the significant environmental challenge of controlling ammonia and methane emissions throughout the handling process. Therefore, there has been concerted efforts towards technological innovation and integration, culminating in the development of a comprehensive approach to ammonia and methane emission reduction. This approach encompasses the whole manure management chain, from the animal housing, through storage / treatment, to the final application to field, henceforth referred to as the “housing-storage/treatment-application” whole chain emission reduction optimized technology model. This study compared and analyzed the environmental and economic cost from a life cycle perspective between the traditional technology model (S1: conventional manure removal, oxidation pond static treatment, and surface application of manure) and the whole chain optimized technology model (S2: surface acidification for open animal building based on conventional manure removal, multi-layer gas supply reactor composting, oxidation pond static treatment, and deep/injection application). The results indicate that the application of technologies, such as manure surface acidification (housing stage), multi-layer gas supply reactor composting (storage/treament stage), and deep/injection application (application stage) can reduce the environmental cost of the corresponding stage by 17.40%, 40.00%, and 79.30%, respectively. Overall, the environmental cost of the whole chain optimized technology model (S2) was 40.40% lower than that of the traditional techonology model (S1). The direct investment for the traditional technology model (S1) was 70.00 ¥·t⁻¹, while the whole chain optimized technology model (S2) increases the direct investment by 31.00 ¥·t⁻¹ compared to the traditional techonlogy model (S1), reaching 101.00 ¥·t⁻¹. Owing to the social and economic benefit of ammonia reduction, the whole chain optimized technology model (S2) can achieve social and economic benefit of 51.52 ¥·t⁻¹. In conclusion, utilizing the whole chain optimized technology model (S2) for reducing ammonia and methane emissions in the process of “housing-storage/treatment-application” can save 20.52 ¥·t⁻¹ compared to the traditional techology model (S1) when processing 1 t livestock manure. If the optimized model is promoted for all farms in Hebei Province, considering the annual production of 140 million t livestock manure in Hebei Province, ammonia and methane emissions can be reduced by 41.30×10⁴ t·a⁻¹ and 44.20×10⁴ t·a⁻¹, respectively. Additionally, an economic benefit of 2.87 billion ¥ can also be achieved by adopting the “housing-storage/treatment-application” whole chain optimized technology model (S2) in Hebei Province. This study underscores the viability and effectiveness of a whole chain optimized technology model as a sustainable solution to the environmental challenges posed by livestock manure management system. This highlights the potential for the widespread adoption of such integrated technology model to enhance the sustainability of livestock farming practices, thereby contributing to the broader goals of environmental protection and sustainable agricultural development.