Manure management at large-scale dairy farms poses environmental risks to air and water resources through greenhouse gas emissions and nutrient pollution. Current practices do not fully utilize the organic matter and nutrients contained in manure. This work evaluated the environmental performance of novel nutrients, energy, and water innovations for resource recovery (NEWIR) system intended to improve the sustainability of dairy manure management by reducing environmental impacts and recovering valuable resources from the manure. NEWIR consists of hydrothermal carbonization (HTC) for energy recovery, algae cultivation for nutrient recovery, and membrane distillation for water recovery. Life cycle assessment was used to compare the NEWIR system with conventional dairy manure management practices and to identify the benefits and unintended consequences of resource recovery. Results show vastly improved nutrient management performance by NEWIR, with marine and freshwater eutrophication potentials reduced 0.148 kg N-equivalent (eq.) and 0.168 kg P-eq. per functional unit, respectively, compared with conventional practices. NEWIR also reduces global warming potential (GWP) by 15% when recovered energy and nutrients are considered. However, NEWIR has higher water consumption than conventional practices, primarily due to the dilution water needed to support algae growth in HTC aqueous products. The dominant contributor to environmental impacts in NEWIR is algae cultivation, primarily due to buffering chemicals required to maintain high pH growth conditions for Spirulina maxima. Uncertainty analysis shows that NEWIR GWP may exceed that of the conventional farm, highlighting the need to reduce the environmental impacts of algae cultivation. Although additional work is needed to optimize algae cultivation and reduce GWP, NEWIR shows considerable potential to improve nutrient management and energy recovery from dairy manure.

中文翻译：

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大型奶牛场营养、能量和水综合回收的生命周期评估

大型奶牛场的粪便管理通过温室气体排放和养分污染对空气和水资源构成环境风险。目前的做法并没有充分利用粪便中的有机物和营养物质。这项工作评估了用于资源回收 (NEWIR) 系统的新型养分、能源和水创新系统的环境性能，旨在通过减少环境影响和从粪便中回收有价值的资源来提高奶牛粪便管理的可持续性。NEWIR 包括用于能量回收的水热碳化 (HTC)、用于养分回收的藻类培养和用于水回收的膜蒸馏。生命周期评估用于将 NEWIR 系统与传统的奶牛粪便管理实践进行比较，并确定资源回收的益处和意外后果。结果显示，NEWIR 大大提高了养分管理性能，海洋和淡水富营养化潜力降低了 0.148 千克氮当量（eq.）和 0.168 千克磷当量。每个功能单元，分别与传统做法相比。考虑到回收的能量和营养物质，NEWIR 还将全球变暖潜能值 (GWP) 降低了 15%。然而，NEWIR 的耗水量高于传统做法，这主要是由于 HTC 水性产品中支持藻类生长所需的稀释水。NEWIR对环境影响的主要贡献者是藻类种植，最大螺旋藻。不确定性分析表明，NEWIR 的 GWP 可能超过传统农场，突出了减少藻类养殖对环境影响的必要性。虽然需要额外的工作来优化藻类培养和降低 GWP，但 NEWIR 显示出在改善营养管理和奶牛粪便能量回收方面的巨大潜力。