Crop fields can be fertilised by application of manure because manure contains fertilising elements such as N and P, and organic matter that enhances soil physical properties. However, application of manure may also cause P and N pollution of surroundings, odour emission and waste of energy. A solution may be to apply an improved liquid manure fraction resulting from manure separation and anaerobic digestion. As previous studies have only focused on the factors individually, we carried out here a system analysis with the aim of optimising all the factors simultaneously. We tested three solid-liquid separations on raw manure and manure pre-digested in a biogas reactor, with the separation treatments being coagulation, flocculation and filtration, which differed mainly with respect to coagulant volume, and the N:P ratio of the products was measured. The NH₃ and odour emission was determined from the liquid fractions during storage and after soil application, while the energy produced at anaerobic digestion of the solid fractions was measured. Our results show that energy production at digestion increased with decreasing coagulant volume, but was largely unaffected by anaerobic digestion whether performed both before and after or only after separation. Odour generation was reduced by pre-digestion. With increasing coagulant volume and without pre-digestion, the nutrient value of the liquid fraction was improved the most, as shown by an increase in the N/P ratio of the liquid fraction and by a decrease in NH₃ emissions from stores and fields. The data proved that mechanical separation of raw manure, added coagulant and polymer, followed by anaerobic digestion of the solid fraction was the optimum strategy from a whole animal manure management perspective. The coagulant volume can be adjusted to favour either nutrient value and NH₃ emission, or energy production.

中文翻译：

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厌氧消化和分离对粪便的营养价值，气味排放和能量产生的影响

由于肥料中含有氮，磷等肥料元素以及能提高土壤物理特性的有机质，因此可以通过施肥来施肥。但是，施肥还可能导致周围环境的磷和氮污染，气味散发和能源浪费。一种解决方案是施加由粪便分离和厌氧消化产生的改进的液体粪便部分。由于先前的研究仅关注各个因素，因此我们在此处进行了系统分析，旨在同时优化所有因素。我们对生粪和在沼气反应器中预消化的粪便进行了三项固液分离测试，分离处理为混凝，絮凝和过滤，主要区别在于混凝剂的体积，产品的N：P比为测量。_由图3可知，在储存期间和土壤施用后，由液体部分确定了气味散发，同时对固体部分进行厌氧消化所产生的能量进行了测量。我们的结果表明，消化时的能量产生随着凝结剂体积的减少而增加，但是无论厌氧消化是在分离之前还是之后或仅在分离之后进行的，在很大程度上不受厌氧消化的影响。预先消化减少了气味的产生。随着凝结剂体积的增加和没有预先消化，液体部分的营养价值得到最大程度的改善，如液体部分的N / P比增加和NH ₃减少所显示商店和田地的排放。数据证明，从整个动物粪便管理的角度来看，机械分离生粪，添加凝结剂和聚合物，然后进行厌氧消化固体部分是最佳策略。可以调节凝结剂的体积，以有利于营养价值和NH ₃排放或产生能量。