Abstract
Today, global focus of research is to explore the solution of energy crisis and environmental pollution. Like other agricultural countries, bulk quantities of watermelon peels (WMP) are disposed-off in environment as waste in Pakistan and appropriate management of this waste is the need of hour to save environment from pollution. The work emphasizes the role of ethanologenic yeasts to utilize significant sugars present in WMP for low-cost bioethanol fermentation. Dilute hydrochloric acid hydrolysis of WMP was carried out on optimized conditions employing RSM (response surface methodology) following central composite design (CCD). This experimental design is based on optimization of ethanologenesis involving some key independent parameters such as WMP hydrolysate and synthetic media ratio (X1), incubation temperature (X2) and incubation temperature (X3) for maximal ethanol yield exploiting standard (Saccharomyces cerevisiae K7) as well as experimental (Metchnikowia cibodasensisY34) yeasts. The results revealed that maximal ethanol yields obtained from S. cerevisiae K7 was 0.36±0.02 g/g of reducing sugars whereas M. cibodasensisY34, yielded 0.40±0.01 g ethanol/g of reducing sugars. The yeast isolate M. cibodasensisY34 appeared as promising ethanologen and embodies prospective potential for fermentative valorization of WMP-to-bioethanol.
Highlights
Many eco-friendly projects are going on in transportation sector for sustainable development
Hydrochloric acid saccharification of WMP hydrolysates (WMPH) The watermelon peels (WMP) waste was subjected to hydrolysis at optimized conditions viz 6% hydrochloric acid (HCl) concentration, 100 °C temperature and 60 minutes
Lignocellulosic biomass (LCB) e.g. watermelon peels for ethanol production can provide a viable substitute as substrate for renewable, sustainable biofuel production that is non-petroleum based and non-polluting for the environment (Goh et al, 2010; Mahmood et al, 2021)
Summary
Many eco-friendly projects are going on in transportation sector for sustainable development. Rapid industrialization worldwide in last few decades resulted in the emission of harmful gases like CO2, SO2, NO and NO2 associated with fossil-fuels combustion (Robak and Balcerek, 2018). If the consumption of fossil-fuels in transport and other sectors continues at high rate, there is a risk of depletion of fossil-fuels within fifty years (Sheehan et al, 2000). As lignocellulosic biomass is used currently as low cost substrate for biofuel production either liquid or in gaseous form. These biofuels are far way cheaper than fossil fuels (Reijnders, 2006; Waheed et al, 2021). Sustainable bioproduction employing abundant and renewable biomass resource, as well as less greenhouse gasses (GHGs) such as carbon dioxide released to environment (Cadenas and Cabezudo, 1998)
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