Livestock Manure Digestate Treatments to Reduce GHG and NH3 Emissions and Meet Crop Nutrients Requirement: The Limit DGGAS Project Experience

Agriculture in the EU contributes significantly to greenhouse gas (10.3%) and ammonia emissions (94%). Poor management of animal manure leads to excessive nitrogen and phosphorus losses, harming ecosystems. Anaerobic digestion (AD) helps manage manure by producing biomethane and stabilized effluents but does not reduce nitrogen and phosphorus content, requiring additional treatments to meet environmental standards. The PRIN project LiMIT DGGAS (2023-2025) is testing nutrient recovery strategies from digestate in Torino and Napoli, Italy. Strategies include liquid phase separation and NH3 stripping, and vermicomposting of the solid phase in Napoli, while Torino focuses on cascade separation and ultrafiltration. Italian ryegrass will be used to evaluate fertilization efficiency, nutrient release, and emissions, compared with controls using mineral and no fertilizers. The project aims to reduce treatment constraints, enhance fertilization efficiency, estimate ammonia and GHG emissions, and perform techno-economic and territorial assessments. The goal is to improve by-product quality, promote digestate use in agriculture, and reduce environmental impacts in line with policy and stakeholder requirements.