Prospective life cycle analysis of an integrated biorefinery for production of lactic acid from dairy side streams

Currently, dairy processing industries face a significant issue relating to disposal of waste. Whey permeate (WP) and delactosed whey permeate (DLP) represent a key challenge for dairy processors in view of their high organic loads and lack of reliable current disposal routes, creating a sustainability bottleneck for the expansion of milk production in the EU’s “post-milk-quota era”. The AgriChemWhey (ACW) project seeks to diversify the dairy industry activities by creating a viable way to sustainably valorize the dairy side streams (DSS) into high value biochemicals (esp. lactic acid (LA)). ACW aims to advance this innovative technology through the integration, optimization and scale-up of the whole process chain for lactic acid (LA) production through conducting trails over a pilot scale and subsequently building the world’s first-of-a-kind integrated flagship biorefinery with production capacity of 20,000 t LA per year in Ireland. Henceforth, it is imperative to assess the environmental impacts of such emerging biorefining activities, to validate the anticipated benefits of such operations at commercial scale. This study developed a framework methodology for scaling up emerging biorefinery technologies, that bridges the gap between establishing pilot bioprocess data and prospective LCA, as well as generates industrial scale LCI using simulation tool (SuperPro Designer®). Consequently, two-step environmental assessment i.e., Attributional life cycle assessment (ALCA) and Consequential life cycle assessment (CLCA), was performed to assess the environmental sustainability of the commercial scale biorefinery. This thesis demonstrates the application of the proposed methodology at a higher TRL level 7, that offers an opportunity to predict uture and current biorefinery performance and realize resource requirements and hotspots within the process as well as its associated environmental impacts in the pilot developmental stage. In addition, this research reveals that the conducting LCA at pilot scale stage overestimates the environmental impacts as material and equipment capacities at the pilot stage don’t corresponds to industrial scale. Application of ALCA demonstrates the status quo of the commercial biorefinery system (gate-to-gate) with fermentation and evaporation stages as hotspots in terms of higher CO2 emissions and energy consumption, respectively. While the dairy farm was identified as a hot spot when the whole supply chain (cradle-to-gate) was considered in the study. CLCA highlights the importance of evaluating the future decisions such as utilization of biorefinery by-products in symbiosis with other partner industries and usage of renewable energy to improve the environmental performance of the biorefinery. The gate-to-gate emissions were considerably reduced but the cradle-to-gate emissions remained unaffected as the dairy farm accounts for 88% of the total emissions. Further, scenario analysis emphasizes the fact that system expansion led to higher savings in emissions and energy than the allocation methods employed (no allocation and economic allocation) for multifunctional LA production process. This research thesis also determines how the future market demand of LA influences the biorefinery sustainability and recommended that effective management of the upstream supply chain by-products (increasing dairy beef integration) would not only help in reduction of emissions at the dairy farm level in Ireland, but also could encourage production of dairy based sustainable biochemicals (esp. LA) by reducing the carbon footprint at the feedstock or upstream levels. Overall, this research concludes that integration of prospective environmental assessment with system analysis data at a higher TRL level (7) offers an opportunity to identify hotspots and recommend alternative strategies to improve the environmental sustainability of the dairy based biorefinery system at the pilot developmental stage.