Utilisation of Australian pineapple (Ananas comosus) processing waste for the production of renewable energy

Mahale, Kiran Ramesh (2021) Utilisation of Australian pineapple (Ananas comosus) processing waste for the production of renewable energy. [Thesis (PhD/Research)]

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Abstract

Globally, Pineapple, Ananas comosus,is the third most popular tropical fruit grown, after citrus and banana,and is the third most popular juice after orange and apple. The current and increasing consumption of fruit juice and related products has resulted in the growth of the fruit processing industry, which translates into a large generation of waste. Pineapple is processed into canned juice or slices, jam, and glazes so the fruit can be available year-round. Processing generates 40-55% of waste in the form of a crown, outer peel, core,and bottom slice. The waste produced during the processing of the fruit poses significant environmental problems. The debris from the fruit processing industry contains nitrogen and phosphorus along with a high content of carbohydrates and moisture which makes it an ideal substrate for microbes to grow and create an environmental hazard. Until recently, processing waste was considered a liability and mainly sent to animal feed processing plants, composting,or landfills. In recent years, strict government policies on landfill meant that sending processing waste to landfills is a less economic proposition. To reduce the quantity of waste, processors are forced to develop alternative technologies that can either create new products from waste or reduce the environmental impacts of their operations.This study developed and optimized the effects of different chemical pre-treatments using various concentrations (0.5%, 1%, 3%, 5%, (w/v))of sulfuric acid (H2SO4), phosphoric acid (H3PO4), sodium hydroxide (NaOH) or calcium hydroxide Ca(OH)2. The effect of this chemical treatment followed by enzymatic treatment (Cellulase) was investigated and optimized for the production of fermentable sugar, to be converted to bioethanol using yeast. The sample treated with 1% NaOH gave the highest amount of reducing sugars (265.8 ± 4.1 g/L) after 7 days followed by 229.6 ± 5.2 g/L in the untreated raw pineapple waste samples and 0.5% Sulphuric acid with 191 ± 5.2 g/L. Enzymatic hydrolysis using a dosage of 320 μL of commercial cellulase resulted in a 79% increase in reducing sugar concentration after 24 hours, with a maximum of 9.45 ±0.94 g/L ethanol obtained after 48 h of fermentation. Further to chemical pre-treatment, the effect of physical and combined physical and chemical pre-treatments was studied and optimized using microwave irradiation to shorten the time frame. The effectiveness of microwave-assisted alkaline sodium hydroxide (NaOH) and acidic sulfuric acid (H2SO4) was studied using concentrations of 0.5% and 1% at a microwave power level of 100% and 50% for 1 and 2 minutes respectively. The highest concentration of reducing sugars was 298.2g/L using 0.5% sulfuric acid and 100% for 1 minute. Microwave irradiation for a longer time (2 min) led to hydrothermal degradation of sugars and resulted in a lower amount of reducing sugar (231.6 ± 1.9 g/L). 160 μL of commercial cellulase enzyme was used to further hydrolyze the pretreated samples. 1% H2SO4 pre-treatment with 2 min microwave heating at 100% power produced the highest amount of phenolic content of 0.918 ± 0.06 mg GAE/mL. The resulting solid residues of pineapple processing underwenta pyrolysis process with a temperature ramp-up rate of 10 °C per min to three different temperature set points of 350 °C, 750 °C, and 900 °C all withholding time of 2 h. The characteristics of these samples were compared using a range of analytical methods, which were used to interpret the mechanism of removal of arsenite [As(III)] from surface water. The samples prepared at 900 °Chad the highest removal capacity for As(III) at 9.21 μg/g. This study confirms that pineapple waste can be readily used for the production of fermentable sugars and conversion to ethanol. The solid residues can be further used in the production of biochar. This biochar can be then utilized as adsorbents for many useful environmental applications.


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Item Type: Thesis (PhD/Research)
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Sciences (6 Sep 2019 -)
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Sciences (6 Sep 2019 -)
Supervisors: Brown, Lindsay; Panchal, Sunil; Trzcinski, Antoine; Lynch, Mark
Date Deposited: 10 May 2021 05:31
Last Modified: 29 Jul 2021 05:29
Uncontrolled Keywords: pineapple, Ananas comosus, environmental applications; renewable energy
Fields of Research (2008): 09 Engineering > 0913 Mechanical Engineering > 091305 Energy Generation, Conversion and Storage Engineering
10 Technology > 1003 Industrial Biotechnology > 100303 Fermentation
09 Engineering > 0904 Chemical Engineering > 090410 Water Treatment Processes
Fields of Research (2020): 40 ENGINEERING > 4011 Environmental engineering > 401106 Waste management, reduction, reuse and recycling
40 ENGINEERING > 4017 Mechanical engineering > 401703 Energy generation, conversion and storage (excl. chemical and electrical)
31 BIOLOGICAL SCIENCES > 3106 Industrial biotechnology > 310603 Fermentation
Identification Number or DOI: doi:10.26192/X4XE-9E47
URI: http://eprints.usq.edu.au/id/eprint/41949

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