INNOVATIVE BIOENERGY SOLUTIONS FOR DEVELOPING NATIONS: DARK FERMENTATION AND ANAEROBIC DIGESTION OF ABATTOIR WASTE

This study investigates the energy recovery potential of abattoir waste by subsequent Dark Fermentation (DF) and Anaerobic Digestion (AD) processes. The 2-reactor system assesses the effect of recycling and parametric optimisation. A simulation model based on the Anaerobic Digestion model 1 (ADM1) was developed and applied for biogas production, which defines carbohydrates, lipids and proteins (CLP) as the main components of anaerobic digestion. The motivation for this work emanates from that a major cause for failure of anaerobic plants is inconsistent feedstock and process design, thus, process modelling provides a cheaper and more reliable evaluation of process components and parameters. Furthermore, a great amount of abattoir waste is generated, coupled with difficulty in disposal thus raising the waste management cost. The study investigated the effect of CLP on biogas yield and assessed the outcome from a co-digestion of manure, blood, and tissue as major abattoir waste streams. Impact on hydrogen yield was in the order of lipids>carbohydrates>proteins whereas for methane it was carbohydrates>lipids>proteins. Manure had the highest impact on methane yield rate, followed by blood, and tissue, whereas hydrogen production was in the order of blood, tissue, and lastly manure, which performed poorly. Recycling improved methane yield by 32%. The study provides optimisation data and linear correlation models for estimating yield based on the three substrates. The study furthermore presents hydrogen and methane potential of various abattoir waste stream. Based on the South African waste stream, there is potential to generate 0,068 – 156,26 GW of energy from abattoir waste.