Prospects for biogas production and H2S control from the anaerobic digestion of cattle manure: The influence of microscale waste iron powder and iron oxide nanoparticles

• Published in: Waste management (Elmsford) Vol. 101; pp. 141 - 149
• Main Authors: Farghali, Mohamed, Andriamanohiarisoamanana, Fetra J., Ahmed, Moustafa M., Kotb, Saber, Yamamoto, Yuki, Iwasaki, Masahiro, Yamashiro, Takaki, Umetsu, Kazutaka
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2020
• Subjects: Anaerobic digestion; Biogas; Hydrogen sulfide; Iron oxide nanoparticles; Manure; Waste iron powder; Hydrogen sulfide; Manure; Biogas; Iron oxide nanoparticles; Waste iron powder; Anaerobic digestion
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2019.10.003

[Display omitted] •A 1000-mg/L of waste iron improved CH4 yields by 56.89% in AD of dairy manure.•Waste iron powder (WIP, 1000 mg/L) enhanced the rate of hydrolysis (k) by 24.60%.•H2S production was also reduced by 77.24%.•Fe2O3 NPs (1000 mg/L) enhanced CH4 yields by 21.11% and reduced H2S by 53.89%.•WIP is a sustainable means of improving CH4 yield and controlling H2S production. Improving the quality and quantity of biogas usually requires pre-treatment to maximize methane yields and/or post-treatment to remove H2S, which involves considerable energy consumption and higher costs. Therefore, this study proposes a cost-effective method for the enhanced anaerobic digestion (AD) of dairy manure (DM) without pre/post-treatment by directly adding waste iron powder (WIP) and iron oxide nanoparticles (INPs) to batch digesters. The results showed that the addition of iron in the form of microscale WIP (generated from the laser cutting of iron and steel) at concentrations of 100 mg/L, 500 mg/L, and 1000 mg/L improved methane yields by 36.99%, 39.36%, and 56.89%, respectively. In comparison, the equivalent dosages of INPs improved yields by 19.74%, 18.14%, and 21.11%, respectively. Additionally, the highest WIP dose (1000 mg/L) achieved the maximum improvement in the rate of hydrolysis (k), which was 1.25 times higher than in control reactions, and a maximum biomethane production rate (Rmax) of 0.045 L/gVS/d according to kinetic analysis models (i.e., first-order and the Gompertz kinetic models). The rate of H2S production was also significantly reduced (by 45.20%, 58.16%, and 77.24%) using the three WIP concentrations in comparison with INPs (which achieved reductions of 33.59%, 46.30%, and 53.52%, respectively). Therefore, the direct mixing of WIP with cattle manure is proposed as a practical and economical means of addressing complex and high-cost pre- and post-treatments that are otherwise required in the digestion process.