Enhanced anaerobic mono- and co-digestion under mesophilic condition: Focusing on the magnetic field and Ti-sphere core–shell structured additives

[Display omitted] •Magnetic field and Ti-sphere core–shell structured additives are firstly used in AD.•Optimized 5 mT magnetic field intensity exhibits a positive effect in AD systems.•The Ti-2MF-5 increases the biogas yield by 65.53% as compared with the CK.•Enhanced performance is due to the synergistic effect of magnetic field and additive.•A general strategy for understanding enhanced methanogenesis pathway is proposed. Enhancing anaerobic digestion performance is highly desired for its large-scale application. In the present work, magnetic fields (0–30 mT) and Ti-sphere core–shell structured additives (Ti-1 and Ti-2) are simultaneously introduced in anaerobic mono-digestion and co-digestions. Compared with the control group, the Ti-sphere core–shell structured additives increase the biogas yield by 27.12%–65.53% for mono-digestion and 8.47%–35.89% for co-digestion systems under the optimized magnetic field intensity (5 mT), respectively. Meanwhile, the degradation rate of total chemical oxygen demand is 54.68%–69.14% for anaerobic mono-digestion and 53.03%–78.25% for anaerobic co-digestion with Ti-sphere core–shell structured additives, respectively. The digestate with Ti-sphere core–shell structured additives exhibits the remarkable stability (45.24%–53.17%) and fertility (4.85%–4.97%). This work clarifies the effect of magnetic field in AD system, and proposes a possible mechanism for understanding the enhanced methanogenesis pathways induced by Ti-sphere core–shell structured additives.