Enhancing biomethane production from municipal sludge by integrating thermal hydrolysis pretreatment with bioelectrochemical anaerobic digestion

This study describes an integrated process combining thermal hydrolysis pretreatment (THP) of municipal sludge with bioelectrochemical anaerobic digestion (BEAD) of the THP liquid. THP conditions optimized using biochemical methane potential (BMP) assays (150 °C, 15 min, 50 kg cm −2 ) resulted in 43% chemical oxygen demand (COD) solubilization without methanogens inhibition. Two BEAD reactors, one with constant electrode polarity (BEAD-1) and another one with periodic polarity reversal (BEAD-2), were compared with an upflow anaerobic sludge bed (UASB) reactor (Control). Both BEAD reactors showed improved CH 4 yield and process stability compared to the Control, with BEAD-2 demonstrating stable CH 4 yields of up to 0.35 L g −1 consumed COD. Operation of BEAD-2 on optimally pretreated THP liquid confirmed the feasibility of the THP-BEAD approach, significantly reducing digestion time and increasing CH 4 production and reactor stability. THP-BEAD integration offers a promising path toward sustainable and circular sludge management. • THP at 150 °C balanced sludge solubilization vs methanogenesis inhibition. • BEAD with periodic polarity reversal increased CH 4 yield and process stability. • THP–BEAD integration reduced treatment time and enabled hydrochar production.