Production of Ethanol from Cassava Peelings Using a Developed Percolation Reactor

Abstract

Bioethanol is an important product in the fuel market obtainable from biomass through fermentation process but direct conversion of cassava peelings to bioethanol as energy by-product is difficult because of its lignocellulosic content. This paper therefore, considers the intermediate route of converting lignocellulosic biomass to fermentable sugar through acid hydrolysis and consequent ethanol production, in a developed percolation reactor. Cassava tuber consists of the starchy flesh and peelings that can be converted into bioethanol but the main agro-waste from cassava crop, aside from the leaves and stem is the peelings. The level of cultivating of the crop in Nigeria is exceptionally high as practised in other developing nations, yet there is no significant use for its peelings which is generated in thousands of metric tonnes annually. Therefore, apercolation reactor is designed for the thermochemical pre-treatment of the lignocellulosic biomass through hydrolysis process with a view to recovering the reducing sugars for fermentation. The reactor is designed to hold 2 kg of pulverised cassava peelings of 0.5≤ and ≥0.3 mm particle size and circulate 3 L of acid liquor for each hydrolysis run. The reactor comprised of a 0.0261 m3 perforated basket, 1.83 W capacity circulation pump in power rating, and a heating chamber containing 3 kW heater. The reactor is designed to operate within the temperature range of 20°C - 180°C, pressure ≤ 45 Nm−2, and liquor flow rate of 4.33 × 10−4 m3·S−1. The reactor was used to convert 500 g of pulverised cassava peelings to sugar laden hydrolysate that subsequently yielded 118 mL of bioethanol through fermentation process in three replicated experiments. The designed percolation reactor could therefore serve as a veritable tool in converting biomass of lignocellulosic origin to chemical and energy products, reduce wastes and promote cleaner environment.