In-situ methane enrichment in anaerobic digestion of food waste slurry by nano zero-valent iron: Long-term performance and microbial community succession

• Published in: Journal of environmental management Vol. 356; p. 120733
• Main Authors: Li, Yong, Zhang, Zhou, Tang, Jieyu, Ruan, Wenquan, Shi, Wansheng, Huang, Zhenxing, Zhao, Mingxing
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2024
• Subjects: Anaerobic digestion; Anaerobiosis; Biomethanation; Bioreactors; Food; Food Loss and Waste; Food waste slurry; Iron; Methane; Microbial community; Nano zero-valent iron; Refuse Disposal; Sewage; Biomethanation; Nano zero-valent iron; Food waste slurry; Anaerobic digestion; Microbial community
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2024.120733

In this work, nano zero-valent iron (nZVI) was added to a lab-scale continuous stirring tank reactor (CSTR) for food waste slurry treatment, and the effect of dosing rate and dosage of nZVI were attempted to be changed. The results showed that anaerobic digestion (AD) efficiency and biomethanation stability were optimum under the daily dosing and dosage of 0.48 g/gTCOD. The average daily methane (CH4) yield reached 495.38 mL/gTCOD, which was 43.65% higher than that at control stage, and the maximum CH4 content reached 95%. However, under single dosing rate conditions, high nZVI concentrations caused microbial cell rupture and loosely bound extracellular polymeric substances (LB-EPS) precipitation degradation. The daily dosing rate promoted the hydrogenotrophic methanogenesis pathway, and the activity of coenzyme F420 increased by 400.29%. The microbial analysis indicated that daily addition of nZVI could promote the growth of acid-producing bacteria (Firmicutes and Bacteroidetes) and methanogens (Methanothrix). •The effect of nZVI dosing rates and dosages on methanogenesis was investigated.•The CH4 content can reach 95% under the daily dosing and dosage of 0.48 g/gTCOD in CSTR.•Different nZVI dosing rate could affect the microbial cells and EPS.•Methanothrix was enriched by DIET enhancement under nZVI daily dosing.