Municipal landfill leachate remediation coupling acidogenesis and bioelectrogenesis for biohydrogen and volatile fatty acids production

This study aimed at sustainable treatment of municipal landfill leachate (MLL) along with resource recovery by integrating acidogenesis and bioelectrogenesis. Initially, during acidogenic fermentation, more than 60 % of MLL COD was converted to biohydrogen (0.23 L/g CODload) and volatile fatty acids (VFAs; 56.15 g COD/L). Acetic (25.09 g COD/L), propionic (1.27 g COD/L), and butyric acid (29.77 g COD/L) made up the majority of VFAs. To increase MLL's further treatment, the left-over COD in the acidogenic effluent was introduced into bio-electrochemical treatment system. Three differently configured bio-electrochemical treatment systems (BET1, BET2, and BET3) were evaluated varying their anode composition. BET1 was operated with a capacitive designed PANi/CNT composite electrode, while BET2 was operated with PANi-SSM and BET3 with a graphite electrode. The modified composite electrode in BET1 played a significant role in leachate treatment (COD removal, 71.21 %) displaying a power density of 35 mW/m2. Apart from higher removal of ammoniacal nitrogen, sulfates and phosphates, the composite electrodes in the BET1 resulted in improved bioelectrogenic activity and capacity of electrons migration between electrode and biocatalyst. Additionally, the modified anode showed higher redox peak currents, lower charge transfer resistance, and ohmic losses.

Automated summary

This study aimed to achieve sustainable treatment of municipal landfill leachate (MLL) and resource recovery by integrating acidogenesis and bioelectrogenesis. The acidogenic fermentation process converted more than 60% of MLL COD to biohydrogen and volatile fatty acids (VFAs). By introducing the leftover COD into a bio-electrochemical treatment system, the modified composite electrode in the BET1 configuration showed significant improvement in leachate treatment, with a COD removal of 71.21% and a power density of 35 mW/m2.