Co-Composting Liquid Digestate and Green Waste: Nitrogen Retention and Process Enhancement

This study explored how liquid residues from biogas production (digestate) can be combined with shredded tree prunings to produce compost. Soaking the prunings in digestate before composting helped retain nitrogen, an important plant nutrient, and provided moisture that supported decomposition. In larger trials, the treated piles heated up quickly, showing active composting, while piles treated only with water showed little activity. This approach offers a promising way to turn two waste streams into a useful resource while reducing nutrient losses.