Effect of Thermal and Mechanical pre-Treatments on the CH4-H2 Production from Water Buffalo Manure in Different Process Conditions

Abstract

Animal manure can be profitably used to produce energy in anaerobic fermenters increasing energy independence and reducing disposal costs and pollution. Animal manure is a low cost substrate rich in carbohydrates, especially suitable for biofuels production, such as hydrogen and methane.
We preliminary studied the effect of mechanical manure pre-treatments on the fermentation process focusing on the biogas yield and composition. In particular, we investigated both the H₂ and CH₄ oriented fermentation.
Our batch reactors consist in 280 ml serum glass bottles hermetically sealed with pierceable rubber cups. The products of fermentation were measured with a micro gas chromatograph, equipped with two capillary columns.
To individuate the most suitable conditions for H₂ production, a manure thermal pre-treatment, used to isolate the H₂-producing bacteria, was investigated.
Preliminary results show that the mechanical pre-treatments do not systematically alter the fermentation process. Concerning the thermal pre-treatment, we found that the CH₄ production is inhibited when the manure is heated at the 90 °C for several hours. Moreover, we identified the most favorable conditions to optimize the production of H₂: i) thermal pre-treatment on the substrate; ii) initial pH ~ 5.0; iii) process temperature of 55 °C. The favorable conditions to optimize the production of CH₄ are: i) initial pH ~ 7.0;ii) process temperature of 37 °C.