Biochar Decarbonizing Olive Mill Wastewater in a Two-stage Anaerobic Co-digestion Process to Obtain a Sustainable Agricultural Biofertilizer

Biochar is a versatile product to be adapted to different sectors due to high adsorption power and conductivity. In the bioenergy and agricultural sector biochar can be applied as supplement to take advantage of its goods properties. Waste with elevate water content that produce high environmental contamination can be treated by anaerobic digestion process to eliminate this contamination, generate renewable energy and biofertilizer. Olive Mill Wastewater represents a significant amount of waste in Spain and the South of Europe and to decarbonizing biochar as supply in the feedstock of anaerobic co-digestion process with a nitrogen rich biomass presents an efficient solution. In this research a two-stage anaerobic co-digestion process have been developed using Olive Mill Wastewater and Legume Plant in the feedstock. The positive influence of biochar in this feedstock have been demostrated obtaining higher methane yields (541 L kg VS-1 (Volatie Solids) against 484 L kg VS-1) and achieving greater stability in the process with lower values of ammonia nitrogen and Volatile Fatty Acids. Quality of digestate as biofertilizer have been enhanced due to the main nutrients analyzed were adsorpted to be liberate slowly for the plant.