Landfill leachate detoxification and decoloration for energy reclamation via microalgae-bacteria synergy

Upcycling of hidden energy and resources from landfill leachate (LL) into short-chains fatty acids (SCFAs) represents a substantially unexploited opportunity to handle environmental issue and achieve a circular economy. Due to high biotoxicity and poor biodegradability, efficient conversion of LL into SCFAs remains a great challenge. Herein, a hybrid electro-biosystem that coupling spatially separate LL electrochlorination, photo-remediation and dark fermentation was constructed to realize LL toxicity alleviation, resource recovery and SCFAs production in cascade. During LL electrochlorination, macromolecular organics evolution and LL toxicity alleviation mechanisms were revealed, in which available Cl^- concentration played key role on LL properties amendment. During microalgae photo-remediation, resources recovery efficiency demonstrates that suitable LL electrochlorination can enhance microalgal photosynthesis and stimulate intracellular energy accumulation. Finally, SCFAs were produced from microalgae biomass via dark fermentation with butyric acid and acetic acid as major products, outputting total energy of 4.38 kJ/L. The work provides a paradigm shift of low-cost LL disposal with extra benefit of SCFAs production.