Systems analysis of digestate primary processing techniques.

Area of Science:

• Agricultural Engineering
• Environmental Science
• Biotechnology

Background:

• Digestate management is crucial for the economic and environmental viability of biogas production.
• Current digestate processing techniques require thorough assessment for diverse feedstocks and geographical contexts.

Purpose of the Study:

• To conduct a technology assessment and systems analysis of primary digestate processing techniques.
• To comprehensively analyze the environmental and cost performance of digestate management.
• To inform decision-making for enhanced sustainability in the biogas sector.

Main Methods:

• Compiled over 100 observations from large-scale biogas plants in Sweden and Belgium.
• Assessed digestate from manure, crops/agro-wastes, and food waste.
• Analyzed climate impact, energy use, and operational costs for no processing, partial, and full processing scenarios.

Main Results:

• Centrifuge, screw press, and rotary drum identified as suitable primary processing techniques.
• Transport costs are a critical factor; storage emissions reduce climate benefits of biofertilizers.
• Processing the liquid fraction significantly impacts cost and climate under Belgian conditions.

Conclusions:

• Optimal digestate processing strategies are context-dependent.
• Local application of liquid digestate as biofertilizer can mitigate costs and environmental impacts.
• An integrated life cycle approach is vital for sustainable digestate management.