Techno-Economic Assessment of a Scaled-Up Meat Waste Biorefinery System: A Simulation Study
While exports from the meat industry in New Zealand constitute a valuable source of foreign exchange, the meat industry is also responsible for the generation of large masses of waste streams. These meat processing waste streams are largely biologically unstable and are capable of leading to unfavourable environmental outcomes if not properly managed. To enable the effective management of the meat processing waste streams, a value-recovery based strategy, for the complete valorisation of the meat processing waste biomass, is proposed. In the present study therefore, a biorefinery system that integrates the biomass conversion technologies of hydrolysis, esterification, anaerobic digestion and hydrothermal liquefaction has been modelled, simulated and optimized for enhanced environmental performance and economic performance. It was determined that an initial positive correlation between the mass feed rate of the waste to the biorefinery system and its environmental performance exists. However, beyond an optimal total mass feed rate of the waste stream there is a deterioration of the environmental performance of the biorefinery system. It was also determined that economies of scale ensure that any improvement in the economic performance of the biorefinery system with increasing total mass feed rate of the waste stream, is sustained. The present study established that the optimized meat waste biorefinery system facilitated a reduction in the unit production costs of the value-added products of biodiesel, biochar and biocrude compared the literature-obtained unit production costs of the respective aforementioned products when generated from stand-alone systems. The unit production cost of biogas was however shown to be comparable to the literature-obtained unit production cost of biogas. Finally, the present study showed that the optimized meat processing waste biorefinery could achieve enhanced economic performance while simultaneously maintaining favourable environmental sustainability.