Even though digestate is rich in plant nutrients, its value as a fertiliser is low due to its high water content of 90 to 95%. Therefore, the main objective of digestate treatment is to extract clean water in order to concentrate the plant nutrients. These are either in solution or attached to organic particles. Roughly, more than 70% of the digestate’s solid particles are smaller than 1 mm and are not easily separated, because of particle size, charge and density. This is one of the reasons why a simple screen separation provides no solution to the problem; however, it is an important step in the treatment chain. During the research project, many different digestate treatment techniques were considered – all of these are recorded in Figure 10. This article provides an overview of the possible techniques for digestate treatment, how they work, and their central research parameters.

Even though digestate is rich in plant nutrients, its value as a fertiliser is low due to its high water content of 90 to 95%. Therefore, the main objective of digestate treatment is to extract clean water in order to concentrate the plant nutrients. These are either in solution or attached to organic particles. Roughly, more than 70% of the digestate’s solid particles are smaller than 1 mm and are not easily separated, because of particle size, charge and density. This is one of the reasons why a simple screen separation provides no solution to the problem; however, it is an important step in the treatment chain. During the research project, many different digestate treatment techniques were considered – all of these are recorded in Figure 10. This article provides an overview of the possible techniques for digestate treatment, how they work, and their central research parameters.