Enhancing the anaerobic bioconversion of complex organics in food wastes for volatile fatty acids production by zero-valent iron and persulfate stimulation

• Published in: The Science of the total environment 2019-06, Vol.669, p.540-546
• Main Authors: Cao, Jiashun, Zhang, Qin, Wu, Si, Luo, Jingyang, Wu, Yang, Zhang, Lulu, Feng, Qian, Fang, Fang, Xue, Zhaoxia
• Format: Article
• Language: English
• Subjects: Anaerobic fermentation; Anaerobiosis; Bacteria; Biodegradation, Environmental; Bioreactors; Fatty Acids, Volatile - analysis; Fermentation; Food; Food wastes (FW); Iron - chemistry; Persulfate (PS); Refuse Disposal - methods; Volatile fatty acids (VFAs); Zero-valent iron (ZVI)
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.03.136

The addition of zero-valent iron (ZVI) and ZVI & persulfate (PS) were efficient approaches to enhance the production of volatile fatty acids (VFAs), especially butyric acid, from food wastes (FW) during anaerobic fermentation. The maximal concentration of VFAs was increased from 1256 mg COD/L in the control reactor to 8245 mg COD/L with ZVI addition, and it was further improved to 9800 mg COD/L with the PS/ZVI treatment. An investigation of the mechanisms revealed that both the ZVI and PS/ZVI treatments improved the bioavailable substrates in FW and enhanced the bioconversion efficiency of fermentation substrates, especially proteins and lipids. The provision of a sufficient amount of bioavailable substrates was advantageous to the enrichment of the functional bacteria that are responsible for the production of VFAs. Additionally, the microbial activity and key metabolic enzymes involved in the biological VFAs generation processes were stimulated in the ZVI and PS/ZVI-added reactors, which jointly contributed to high-rate VFAs yields. [Display omitted] •ZVI and PS/ZVI contributed greatly to the VFAs promotion, especially butyric acid.•The bioconversion of complex organics was improved, particularly protein and lipid.•The functional acidogens for VFAs yield were enriched in ZVI and PS/ZVI reactors.•The microbial activity involved in VFAs yield was stimulated by the ZVI and PS/ZVI.