Enhancement of biogas production from biomass using hydrothermal conditioning and partial oxidation

Abstract EN

While the direct use of biomass as fuel is a proven process, the study presented in this paper is focused on assessing the impact of partial hydrothermal oxidation on wood biomass and wastewater treatment sludge in terms of achieving two objectives: (1) partial destruction of the organic component of the waste; and (2) production of biogas from the organic by-products of hydrothermal treatment.

The hydrothermal treatment conditions employed in the study included temperatures in the range of 100-250oC, reaction time of 20-60 minutes and oxidant (H2O2) dosages of 0-123% of the chemical oxygen demand (COD).

The study confirmed that hydrothermal treatment at the moderate conditions used in the study was capable of reducing the organic content of sludge biomass and wood biomass, with COD removals in the range of 1-60% from the sludge biomass and 1-71% from the wood biomass.

The treatment byproducts responded to anaerobic treatment and produced significant quantities of biogas.

The results confirmed that hydrothermal treatment resulted in significant improvement in the specific biogas production from the wood waste but not from the sludge waste.

For the sludge, the biogas production from hydrothermally treated samples reached 0.24 mL/mg COD compared with 0.18 mL/mg COD from the untreated samples.

For the wood waste, the biogas production from hydrothermally treated samples reached 0.46 mL/mg COD compared with 0.07 mL/mg COD from the untreated samples.

The significant improvement in biogas production from the wood biomass suggested that the organic by-products generated using hydrothermal treatment were more readily available for anaerobic biogas production than the original organic components.