Design and performance optimization of a laboratory scale distiller for high-purity bioethanol production from biomass feedstocks

Abstract

This study presents the design, fabrication, and performance evaluation of a laboratory-scale packed-column distillation system to produce high-grade hydrous bioethanol from fermented mango (Mangifera indica) waste, a locally abundant agricultural residue, using low-cost, locally available materials. The system was engineered as a cost-effective and scalable solution for biomass-based ethanol purification suited to decentralized, small-scale operations. The distillation apparatus incorporates a configurable reflux column utilizing two alternative packing materials steel wool (A1) and Raschig rings (A2) to enhance vapor-liquid contact and improve separation efficiency. Mango waste was collected, prepared, and fermented to produce a crude bioethanol wash, which was then processed at three initial ethanol concentrations (40%, 60%, and 80%, designated B1, B2, and B3, respectively). The two packing materials and three feed concentrations were arranged in a Completely Randomized Design (CRD) in a 2 × 3 factorial layout, replicated three times (18 experimental runs), and the resulting data were analyzed using two-way ANOVA and linear regression. The results demonstrate that packing material significantly influenced system performance. Raschig rings achieved superior outcomes overall, yielding ethanol purity up to 97.83%, a mean distillation efficiency of 73.37% (compared with 65.45% for steel wool), and a mean ethanol recovery of 41.55% (overall mean across both packing materials: 41.51%). Distillation rates ranged from 2.4 to 3.89 L/h depending on feed concentration and packing configuration. Operational parameters showed a rapid start-up time (5-10 minutes) and efficient thermal performance within a boiling range of 70-83°C. A techno-economic assessment indicates that the system is financially viable for small-scale deployment, with a low capital investment (₱6,500) and a total annual operating cost of ₱51,477 against an annual production capacity of 1,648.8 L, giving a unit production cost of approximately ₱31.22/L. At an assumed selling price of ₱35.00/L, the system generates an estimated annual net income of ₱5,496, a payback period of 1.18 years, and a return on investment of 84.55%. (1 US Dollar = 62 ₱) The study demonstrates the technical and economic feasibility of an optimized packed-column distillation system for purifying mango waste-derived bioethanol, offering a sustainable pathway for decentralized biofuel production and agricultural waste valorization in the Philippines.