Bio-Refining of Carbohydrate-Rich Food Waste for Biofuels

Abstract

Abstract:The global dependence on finite fossil fuel-derived energy is of serious concern given the predicted population increase. Over the past decades, bio-refining of woody biomass has received much attention, but data on food waste refining are sorely lacking, despite annual and global deposition of 1.3 billion tons in landfills. In addition to negative environmental impacts, this represents a squandering of valuable energy, water and nutrient resources. The potential of carbohydrate-rich food waste (CRFW) for biofuel (by Rhodotorulla glutinis fermentation) and biogas production (by calculating theoretical methane yield) was therefore investigated using a novel integrated bio-refinery approach. In this approach, hydrolyzed CRFW from three different conditions was used for Rhodotorulla glutinis cultivation to produce biolipids, whilst residual solids after hydrolysis were characterized for methane recovery potential via anaerobic digestion. Initially, CRFW was hydrolysed using thermal-(Th), chemical-(Ch) and Th-Ch combined hydrolysis (TCh), with the CRFW-leachate serving as a control (Pcon). Excessive foaming led to the loss of TCh cultures, while day-7 biomass yields were similar (3.4-3.6 g dry weight (DW) L −1 ) for the remaining treatments. Total fatty acid methyl ester (FAME) content of R. glutinis cultivated on CRFW hydrolysates were relatively low (~6.5%) but quality parameters (i.e., cetane number, density, viscosity and higher heating values) of OPEN ACCESSEnergies 2015, 8 6351 biomass extracted biodiesel complied with ASTM standards. Despite low theoretical RS-derived methane potential, further research under optimised and scaled conditions will reveal the potential of this approach for the bio-refining of CRFW for energy recovery and value-added co-product production.

Fruit Wastes Hydrolysates as Feedstock: Pre-Treatment Strategies for Cost-Saving and Sustainable Microalgae Cultivation

“…Fruit wastes such as peels, pomace and seeds could be a good feedstock [9] and contains higher reducing sugar values. Pre-treatment of fruit wastes alters the physio-chemical-biological characteristics resulting in release of sugars and nutrients [10]. Growth medium influences the growth rate, biomass and lipid production in microalgae and selection of appropriate pre-treatment is necessary to produce a growth medium from fruit wastes.…”

Realising the circular bioeconomy

“…Dahiya et al, 2018). To date, hardly any food waste is utilised in this fashion, despite an estimated annual global deposition of about 1.3 billion tonnes of food waste in landfills (Hao et al, 2015). This suggests that one-third of the total global food production is wasted each year, costing the global economy over USD 900 billion 3 .…”

Pyrolysis Characteristics and Kinetics of Food Wastes

“…The activation energy (E) can be obtained at a fixed conversion rate using the relationship between ln(dX/dt) and 1/T from Equation (9). The intercept value of Equation (9) can be expressed as Equation (10), and it is possible to obtain the frequency factor by fixing the order of reaction at a fixed conversion rate using this equation:…”