# Digestate Management and Processing Practices: A Review
## 6 Regulations and Standards for Digestate Management  
In the longer term, the European Union (EU) has set an enthusiastic target of building a low C economy and achieving an 80-95% reduction in GHG emissions by 2050, with renewables accounting for between 55% and 75% of gross final energy consumption [182]. However, only a limited amount of waste produced in the EU is recycled (43%), while the rest ends up in landfills (31%) or is incinerated (26%). According to European Commission, it has been estimated that 600 million tons more of waste could be recycled or reused in the EU [183]. In light of this insight, EU energy, and climate policies, especially in the last decade, are focused on promoting and developing a circular and innovative, resource-efficient, and competitive bioeconomy that combines food security with the sustainable use of renewable resources for industrial purposes. The bio-based economy plays a key role in replacing fossil fuels for energy applications, as well as for chemicals and material applications, through a circular economy, concerning recycling and reuse [184,185]. This policy has stimulated a rapid emergence of new AD plants in the EU [186]. The number of AD plants in the EU increased from 6227 [187] to 18202 [188] between 2010 and 2018. While biogas is the main product of AD, millions of tons of DG are produced annually as a by-product. DG requires proper management and/or disposal and is typically mechanically separated into liquid and solid fractions [186] and can be used for various purposes such as fertilizer, animal feed, bedding, raw material for construction, energy source, etc. [189].  
The first European regulation to address the issues of DG was the Waste Directive from 1991, which referred to the protection of surface water and groundwater from pathogens affecting compromise the quality of water. Since then, EU political authorities have passed further legislation. According to the many EU Member States, DG was considered waste. In 2010, the European Commission highlighted the excessive production of waste, mainly due to common practices and inadequate waste management systems. Therefore, the Commission established that DG and compost obtained from bio-waste (forestry and agricultural residues, manure and sewage sludge, and other biodegradable materials such as natural textiles, paper, or processed wood) are considered used materials [89,183]. The recycling of bio-waste consists of the appropriate treatment by composting to produce organic fertilizers that can replace mineral fertilizers and be used on the land. The final use of the DG on land represents the essential stage for the effective closure of the loop consistent with the zero waste goals [89]. The problem with DG is that there is a lack of confidence among end-users, which means that most farmers are poorly (or even incorrectly) informed about the benefits of DG, which often makes them reluctant to apply it to their land [190,191]. This problem could be solved by regulating the application of DG in a way that does not have a negative impact on the soil. Thanks to the Implementing Regulation from 2014, DG from biogas produced via AD of by-products of animal origin mixed with materials of plant origin, has been recognized as fertilizer ready for market. Pending the adoption of the regulation on fertilizers from organic waste, already proposed in 2016, DG could be considered a marketable organic fertilizer [183].  
However, by now, there is no EU regulation on DG, and only local and volunteer basis guidelines have been proposed by some EU Member States [50; 88; 183]. On the other hand, the European Commission is considering proposing minimum standards and guidelines for use of DG in agriculture via revision of the Sewage Sludge Directive.