Development of a Low-Cost and Sustainable Biodiesel Reactor Using Waste Cooking Oil

Abstract

This study developed and evaluated a low-cost biodiesel batch reactor with an integrated washing system for processing waste cooking oil into biodiesel. The reactor was fabricated from locally available materials and designed to perform transesterification and water washing in the same vessel to reduce equipment requirements and simplify purification. Two catalyst systems, KOH and NaOH, were tested using identical volumes of waste cooking oil and methanol. The resulting biodiesel samples were analyzed for kinematic viscosity, specific gravity, and pour point following ASTM methods, and preliminary engine observations were conducted on a 12 HP diesel engine using different biodiesel blends. The KOH mixture produced slightly more biodiesel than the NaOH mixture, and both samples met the standard limits for viscosity and pour point. Specific gravity values were slightly below the ASTM range but remained close to acceptable limits for small-scale applications. Engine observations provided initial insights into smoke characteristics and fuel behavior, although the tests were qualitative and conducted without load. The cost comparison showed that the fabricated reactor was significantly more affordable than commercially available units, while offering a larger working capacity and built-in washing capability. The findings demonstrate the technical feasibility of producing biodiesel from waste cooking oil using an affordable, locally fabricated reactor and highlight its potential value for community-level fuel production. Further studies with controlled reaction conditions, replicated trials, and standardized engine testing are recommended to strengthen performance evaluation.