In a recent study published in Recycling journal, researchers César Omar et al., explored how biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More can enhance methane production in anaerobic digestion systems. The research focuses on converting anaerobic pig sludge, a problematic byproduct of pig farming, into a valuable resource.  

The study addresses the environmental and health risks associated with improper management of anaerobic pig sludge, which contains heavy metals and excess nutrients that can pollute soil and water. The authors explore a circular approach where this sludge is converted into biochar, a material that can enhance methane production during anaerobic digestion. This process is particularly effective when biochar is produced through co-pyrolysis—a process that involves the simultaneous pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of anaerobic sludge and residual lignocellulosic biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More.  

Researchers conducted experiments to determine the optimal co-pyrolysis biomass ratio and to assess the effects of biochar dosage and particle size on methane production. They found that biochar derived from a mixture containing up to 25% anaerobic pig sludge increased methane yield by 74.49%, without compromising its catalytic effect. Methane yield was also significantly influenced by biochar dosage and particle size, with the best results observed at dosages of 12-18 g/L.  

This study demonstrates the potential of co-pyrolysis of anaerobic pig sludge and lignocellulosic residues as a circular solution for integrated waste management and energy production. By converting a problematic waste into biochar, which then enhances methane production, this approach offers a sustainable way to reduce environmental risks, produce renewable energy, and create a circular economy within pig farming.  

Source: Díaz Lara, C.O.; Cabañas Vargas, D.; Sacramento Rivero, J.C.; Baz-Rodríguez, S.; Ruiz Espinoza, J.E.; Aguilera-Cauich, E.A.; Baas-López, J.M.; Pacheco-Catalán, D.E. Towards Circularity in Anaerobic Digestion: Methane Yield Enhancement Using Biochar from Co-Pyrolysis of Anaerobic Sludge and Residual Lignocellulosic Biomass. Recycling 2025, 10, 84.1