Anaerobic Fermentative Co-production of Hydrogen and Methane from an Organic Fraction of Municipal Solid Waste

Abstract

In order to improve energy recovery efficiency, the fermentative hydrogen production from organic fraction of municipal solid waste was followed by methane production using the residual of hydrogen production as a substrate. Six individual components of organic fraction of municipal solid waste, including rice, potato, lettuce, lean meat, peanut oil, and banyan leaves, were selected as experimental materials. The results showed that at the hydrogen production stage, the hydrogen yields were 125, 103, 35, 0, 5, and 0 mL/gVS for rice, potato, lettuce, lean meat, peanut oil, and banyan leaves, respectively. During the methane production stage, the methane yields were 232, 237, 148, 278, 866, and 50 mL/gVS. For example, for rice the co-production of hydrogen and methane increased the energy efficiency from 7.9 to 56.3% compared with single hydrogen production.

Keywords:

• anaerobic fermentation
• co-production
• hydrogen
• methane
• municipal solid waste

Notes

^a Energy efficiency is calculated based on the heating value of C₆H₁₂O₆ (2,888 kJ/mol), H₂ (242 kJ/mol), and CH₄ (801 kJ/mol).

^a The inoculum was methane production seed.

^b The pH was adjusted by adding 2 mol/L HCl.

^c The inoculum was methane production seed.

^d The pH was adjusted by adding 2.5 mol/L NH₄HCO₃.

^e The fermentation finished until no gas produced.

^f The pH was adjusted by adding 5 mol/L KOH in order to avoid ammonia inhibition.

^a The added COD was calculated as: TS_added × [C] × 2.67 + TS_added × [H] × 8 − TS_added × [O].

^b The undegraded COD was calculated as: Added–intermediate–hydrogen.

^c The residue includes the undegraded COD and the COD converted into biomass, calculated as: Added–end intermediate–hydrogen–methane.

^a Heat value directly determined.

^b Heat value calculated based on 242 kJ/mol.

^c Heat value calculated based on 801 kJ/mol.