Waste cleaning waste: Ammonia abatement in bio-waste anaerobic digestion by soluble substances isolated from bio-waste compost

Abstract Soluble bio-based substances are isolated from the alkaline hydrolysate of composted urban gardening wastes. These substances are capable to reduce the ammonia content in municipal biowaste anaerobic digestates. The present work reports the anaerobic fermentation of the organic humid fraction of solid municipal biowaste carried out in the presence the above soluble substances, added at 0.05–0.2% concentration in fermentation slurry. The results show that the ammonia in the digestate obtained under these conditions is 70–100% lower than the ammonia present in the digestate of control fermentation without addition of soluble biobased substances. Operational cost savings (up to 1.1 € per abated ammonia N kg) may result for the anaerobic digestion performed in the presence of the above soluble susbtances, compared to conventional technology for the digestate secondary treatment.