Knowledge Base

Digestate treatment covers the range of processes used to prepare digestate for safe storage, transport, valorization, or discharge, and the right combination depends on feedstock, local regulations, and the intended end use. Common treatment steps include:

• Mechanical separation: A screw press separator divides digestate into a solid and a liquid fraction. The solid fraction can be used as a soil improver or bedding material, while the liquid fraction is easier to store, transport, or apply as a liquid fertilizer.
• Pasteurization (hygienisation): Certain feedstocks, such as animal by-products or food waste, must be heat-treated to meet European regulatory standards before the digestate can be used as fertilizer. HoSt’s HoSt Hygienisator® performs this batch, in-vessel heat treatment to ensure the output is safe for agricultural use.
• Heat recovery from digestate: Because digestate leaves the process at a high temperature, its heat can be recovered and reused to preheat the incoming liquid feedstock. This lowers the heat demand of the digesters and improves the overall energy efficiency of the plant.
• Thermal treatment for improved degradation: Technologies such as HoSt’s ThermalTreat® apply pressure hydrolysis to improve the biodegradability of organic material before or during digestion, which reduces sludge volumes and foam formation and supports a more efficient digestate output.
• Further liquid fraction treatment: In water-scarce or strictly regulated regions, the liquid fraction can undergo additional treatment, such as osmotic water recovery, to allow water to be reused for diluting fresh digestate instead of relying on clean water sources.

Choosing the right combination of these treatments allows a biogas plant to turn digestate into a stable, valuable output rather than a waste stream, supporting both the environmental and economic case for anaerobic digestion. HoSt designs digestate treatment into its biogas plants from the start, tailoring the technology to the feedstock, the site, and the destination market for the end product.