Co‐digestion of olive mill wastewater and municipal solid waste landfill leachate promotes medium‐chain fatty acids and hydrogen production.

The management of olive mill wastewater (OMWW) and municipal solid waste landfill leachate presents a significant challenge due to their high concentrations of organic matter and phenolic compounds. These substances complicate treatment processes, hinder their potential use in agriculture, and inhibit key biological processes such as acetogenesis and methanogenesis. Nonetheless, an urgent need remains to develop a sustainable solution for managing hazardous waste while generating valuable resources. This research hypothesizes that co‐digestion can enhance the production of medium‐chain fatty acids (MCFAs) and hydrogen (bioenergy), which are target molecules due to their wide range of applications. Several batch reactor experiments were conducted to investigate the co‐digestion of OMWW and landfill leachate at varying ratios, with and without the addition of ethanol as an electron donor. The results show 30% landfill leachate:70% OMWW, supplemented with ethanol, achieved the highest MCFA production, predominantly of hexanoic acid, along with significant hydrogen generation. Finally, co‐digestion of OMWW and landfill leachate demonstrated significant potential for producing both MCFAs and hydrogen, offering a solution to the environmental issues posed by these effluents and promoting the circular economy. [ABSTRACT FROM AUTHOR]