Optimization of Fermentation Process Parameters for Bioethanol Production from Sri Lankan Overripe Fruits

Bioethanol produced by biomaterials is used in many countries around the world as an alternative option for gasoline, mainly due to its better emission characteristics. Presently, Sri Lanka depends on imported fossil fuel to fulfil the majority of its transportation fuel requirement and also committed to reduce green house gas emission. Therefore, searching for alternative freely available and low-cost bio resources to produce bioethanol is a timely requirement. This research aims to study the possibility of producing bioethanol from Sri Lankan rotten fruits (without skin) using batch fermentation followed by optimization of the fermentation process parameters. Optimization is carried out by using Response Surface Methodology (RSM) and Genetic Algorithm (GA), and Particle Swarm Optimization (PSO). Bioethanol production is carried out using three different overripe fruits: Banana (Musa ssp.) embul kesel variety, Papaya (Carica-papaya) and Jackfruit (Artocarpus heterophyllus) with two different microorganisms (inoculum) at three different fermentation conditions. The maximum ethanol yield (%) obtained with RMS, GA and PSO were 13.39, 13.39, and 13.36 vol.%, respectively, by using Banana (embul kesel variety) fermentation with Pseudomonas mendocina (PM) as inoculum, 1:1 substrate concentration, 5.1 pH and 35oC temperature conditions.