Simultaneous nitrogen removal and methane production from Taihu blue algae against ammonia inhibition using integrated bioelectrochemical system (BES)

Highlights: • An applied voltage of 0.4 V and total solids (TS) ratio of blue algae to anaerobic sludge as 1:1 were selected. • Methane production of BES with TS ratio 1:1 reached 18.7 times of the group with TS ratio 3:1. • Methane production of BES reached 3.18 times of the AD group with the same TS ratio. • More methanogenesis and stress resistant microbial genus could be enriched with TS ratio 1:1. Simultaneous nitrogen removal and methane production using an integrated bioelectrochemical system (BES) during the anaerobic digestion (AD) process of Taihu blue algae were investigated. Upon an applied voltage of 0.4 V and total solids (TS) ratio of blue algae to anaerobic sludge as 1:1, the highest methanogenesis potential as 69.12 mL/g VS could be obtained, attaining 18.7 times of the TS ratio group of 3:1. Moreover, methane production of the integrated BES group reached 3.18 times of the AD group using conical flask, even with the same TS ratio (1:1) and initial ammonia nitrogen concentration (1000 mg NH₄⁺-N/L). Apart from the bettered electrochemical performance, bio-augmented microbial genus responsible for acetoclastic methanogenesis, power generation, resisting to hostile circumstance, co-existence with hydrogenotrophic methanogens could all be enriched. Therefore, integrated BES with appropriate TS ratio under applied voltage might help offset both the ammonia and electrical stress, thereby to maintain enhanced biomethanation performance.