Biosurfactant Production by Fermentation of Palm Oil Agricultural Refinery Waste

Abstract

The palm oil industry in Malaysia is part of the National Key Economic Area (NKEA) program. It is expected to grow over the next decade due to contributions by business opportunities in the upstream expansion, development of existing downstream palm oil activities and biodiesel production, predicted to be worth RM57.6 billion by 2020. Malaysia is the second largest palm oil producer in the world and accounts for 29% of global production and 37% of world exports. In January-June 2017, the crude palm oil (CPO) production was 8.7 million tonnes; a 15% increase compared to the year 2016. Biorefining is the sustainable processing of biomass, such as waste or by-products, into a spectrum of marketable energy and products that combine the latest technology available aiming to achieve the sustainable transformation of biomass into value-added products such as biofuels, energy, chemical and materials. In general, biorefinery technology has been established in palm oil mills and refinery industry by producing biofuels, biogas, bioelectricity and chemicals from by-products such as empty fruit bunch (EFB), palm kernel shell (PKS), palm kernel oil (PKO), palm kernel cake (PKC), press palm fiber (PPF) and palm fatty acid distillate (PFAD) (Ayodele and Cheng, 2016). In this study, the potential of PFAD, a by-product in palm oil refinery, and fatty acid methyl ester (FAME), the biodiesel produced from PFAD though esterification process, were used as carbon source for biosurfactant production. The biosurfactant known as rhamnolipid was produced using P. aeruginosa PAO1 via a fermentation process. The interest in microbially produced biosurfactants has significantly increased in the last decade. By definition, biosurfactants are a diverse group of surface active compounds that are produced from microorganisms and have both hydrophilic and hydrophobic moieties. As biosurfactants are biologically produced molecules, they have been reported to have less toxicity towards the environment, be biodegradable and sustainable as they can be produced from renewable substrates compared to conventional synthetic surfactants. Recent research also found that biosurfactant significantly decreases the surface tension of solutions, has lower critical micelle concentration, higher thermostability and tolerance in extreme pH and ionic strength condition. Vast advantages of biosurfactant make it extensively researched and used for various applications such as in the petroleum industry, food and agricultural industry, biomedical industry, as well as used in bioremediation for toxic chemicals. The production and characterisation of rhamnolipid produced by Pseudomonas aeruginosa PAO1 grown on PFAD under batch fermentation were investigated. Results showed that P. aeruginosa PAO1 can grow and produce 0.43 g/L of rhamnolipid using PFAD as the sole carbon source. Next, the optimization of the fermentation process to improve the rhamnolipid production were designed in term of changes of fermentation culture media and improved the visibility of substrates in culture media. In this stage, the PFAD converted into FAME which directly changed the physical properties of PFAD from solid to liquid. The results showed the maximum rhamnolipid concentration of 3.4 and 2.5 g/L were obtained when 10 g/L PFAD and FAME were used, respectively; while usage of 20 g/L PFAD and FAME achieved rhamnolipid concentrations of 3.2 and 3.1 g/L, respectively. This stage showed a significant increase of rhamnolipid production which revealed the potential of PFAD and FAME on a larger scale. Furthermore, the fermentation was run in a bioreactor to see the potential to scale up in industry. The fermentation process was set-up in 2 L bioreactor using 2% of PFAD and FAME as carbon sources supplemented with the minimal medium at 1 g/L of nitrogen concentration. Crude rhamnolipid production maximum was 1.06 g/L for PFAD and 2.1 g/L for FAME. This work demonstrates the potential for the utilisation of palm

Date of Award	31 Dec 2018
Original language	English
Awarding Institution	The University of Manchester
Supervisor	James Winterburn (Supervisor)