Techno-economic and environmental evaluation of integrated mango waste biorefineries

Abstract

An analysis of process feasibility, economic and environmental performances of mango processing waste biorefineries is presented. Three biorefinery scenarios were modelled in Aspen Plus to integrate the recovery of high-value bioactive compounds, bioethanol, and bioenergy. Fermentation of mango peel to produce bioethanol was evaluated in Scenario 1. Scenario 2 considered the recovery of pectin from mango peel prior to ethanol fermentation while Scenario 3 assessed the sequential recovery of pectin and polyphenols from mango peel before ethanol fermentation. In all three scenarios, anaerobic digestion of wastewater and stillage produced biogas which was co-combusted with mango seed to generate heat and electricity. Co-producing pectin and polyphenols with bioethanol and bioenergy (Scenarios 2 and 3) promotes product diversification and improves profitability. Although Scenario 1 is the least capital intensive, with a total capital investment of 77.1 million USD (compared to 85.2 and 87.5 million USD for Scenarios 2 and 3, respectively), it is not economically attractive with a negative Net Present Value (−142 million USD). Scenario 3 is the most attractive in terms of profitability, with a Net Present Value of 311 million USD compared to 238 million USD for Scenario 2. However, Scenario 2 has the least environmental impacts, with Global Warming Potential at 16.6 kg CO2 equivalent per tonne of mango waste and Fossil Resources Consumption at 5.55 kg oil equivalent per tonne of mango waste compared to Scenarios 1 and 3 with Global Warming Potential values of 21.9 and 32.7 kg CO2 equivalent per tonne of mango waste and Fossil Resources Consumption values of 6.68 and 10.3 kg oil equivalent per tonne of mango waste, respectively. Accordingly, the economic and environmental results suggest that trade-offs between profitability and environmental impacts for the biorefineries should be established in implementation decisions.