POME is a thick concentrated dark brownish colloidal slurry (comprising water, oil and fine cellulosic materials) which is generated as the largest amount of liquid wastes (about 95% water and 5% solids) from the palm oil industry. POME is produced in the form of condensate and clarification sludge from two main processes in the oil mill, namely, sterilisation and clarification, respectively. The sterilisation of FFB, clarifica­tion of the extracted CPO and hydrocylone separation of the cracked mixture of kernel and shells contribute about 36%, 60% and 4% of POME, respectively, in the oil mill (Sethupathi 2004). With about 1.5 m3 (or about 1.5 tonnes) of water used in process­ing 1 tonne of FFB, about half of this quantity (~0.50-0.75 tonnes water) comes out as POME (Alam et al. 2009). In 2004, for instance, about 40 million tonnes of POME was generated from about 372 palm oil mills in Malaysia (Yacob et al. 2005). This figure rose drastically to about 53.1 million tonnes in 2006. Generally, for every tonne of CPO produced, about 3.25 tonnes of POME is generated (Corley and Tinker 2003).

POME contains about 40,500 mg/l total solids (comprising cellulosic materials) and 4,000 mg/l fats, oil and grease (Ma 2000) depending on the method of oil extraction and the characteristics of the FFB. The pH of POME ranges from 4 to 5, whilst its temperature of POME may vary from 80 to 90°C (Ma 2000) due to heat production during the sterilisation and other mechanical processes within the palm oil mill. The biological oxygen demand (BOD) and chemical oxygen demand (COD) of POME are very high exceeding 25,000 mg/l and 50,000 mg/l, respec­tively; hence, they are considered more polluting than domestic sewage (Ma 2000).

POME contains dissolved substances such as protein (about 9.6% DM), carbo­hydrate, nitrogenous compounds (ammonical nitrogen of 20-40 mg/l and total nitrogen of 100-1,200 mg/l) and fats which can be converted into useful materials using microbial processes (Ma 2000). POME contains about 11% cellulose, 7% hemicellulose and 42% lignin on dry basis (O-Thong et al. 2012). The amount of minerals such as phosphorus (about 0.26%), magnesium (about 0.25%) and calcium (about 0.28%) which are found in POME is good for healthy plants’ growth. Muhrizal et al. (2006) reported that POME contains high content of aluminium as compared to that of chicken manure and composted sawdust. POME has been reported by Habib et al. (1997) to contain low concentrations of lead (about 17.5 pg/g) due to the contaminations from the paints and glazing materials used on plastic and metal pipes and tanks in the oil mill.

Ionic liquid (IL), or also known as molten salt, has emerged as one of the potential candidate in the effort of searching for greener catalyst in biodiesel production. It is considered to be superior to its homogeneous catalyst counterpart (i. e., NaOH, H2SO4) in terms of its properties, such as volatility and solubility with reactants. The out­standing volatility of IL is attributed by its low vapor pressure and high thermal stabil­ity. The ionic nature resulted in strong bond between the cation and anion of an IL.

It is considered greener solvent than common volatile organic compound that decomposes at high temperature and released to the atmosphere. Another important characteristic of an IL is its solubility with reactants, especially the poor solubility of IL in biodiesel phase (Fang et al. 2010). This helps to direct the transesterification towards the product side as a result of solubility difference between IL and biodiesel. IL can be synthesized by manipulating the combination of different cations and anions, and the physicochemical and thermal properties are influenced by the types of ions. Figure 9.3 represents some of cations and anions that are available for ionic liquid synthesis.

Cation

Fig. 9.3 Commonly used cations and anions in ionic liquids

Not only IL has excellent properties that portray its greenness than conventional organic solvents, it also has catalytic activity as good as conventional catalysts in biodiesel production.

In the transesterification of cottonseed oil catalyzed by Brqrnsted acidic ionic liquids, Wu et al. (2007) found that the best ionic liquid (1-(4-sulfonic acid) butyl- pyridinium hydrogen sulfate) had almost similar FAME content (81%) compared to the one produced using concentrated H2SO4 catalyst (86%) after 3 h reaction time. The high catalytic performance was contributed by its strong Brqrnsted acidity, the type of cation used, and also the length of carbon chain in IL catalyst. Meanwhile, Liang et al. (2009) used ethylammonium chloride ([EtNH3][Cl]) mixed with metal chlorides that provide Lewis acid sites for the conversion of soybean into FAME. The comparison shows that the novel catalyst resulted in highest biodiesel yield than other traditional conventional catalyst, such as sulfuric acid, phosphoric acid (H3PO4), and p-toluenesulfonic acid (PTSA).

The combination of its cation and anion governs the performance of an IL. Zhang et al. (2009) prepared several Brqrnsted acidic ionic liquids that were later used for esterification of FFAs. Based on the analytical productivity of ethyl oleate, they found that ILs with same cation (i. e., CH3SO3Hmim) but different anions resulted in different yields. [CH3SO3Hmim][CH3SO3] catalyst performed the best for the same cation. The stronger acidity of IL was believed to be influenced by the stronger acid used to acidize the inner salt MIMPS. On the other hand, [NMP][CH3SO3] stands out as the catalyst that produced the highest biodiesel yield (96.5%) for the same anion. Added with the economical cost of cation and easier catalyst preparation, the

catalyst seems to be a good candidate for conversion of FFAs and biodiesel

synthesis.

The catalytic activity of ILs can be enhanced by means of the inclusion of metal chlorides. Guo et al. (2011) studied the addition of metal chlorides in ILs to check their effect on esterification of oleic acid and transesterification of crude Jatropha oil (CJO) to produce biodiesel. After the screening of several commercial ILs for con­verting oleic acid to methyl ester, 1-butyl-3-methylimidazolium tosylate ([BMIM] [CH3SO3]) was further studied as it gave the highest conversion rate. Later, several divalent and trivalent metal chlorides were added to the IL and tested for the trans­esterification of CJO. Results shown that the IL with FeCl3 has the highest biodiesel yield (99.7%) among all the metal chlorides studied. They concluded that trivalent metallic ions showed higher activity due to their stronger Lewis acidity than biva­lent metallic ions.

Ionic liquids also have the edge over conventional catalysts in terms of their cata­lytic performance when different feedstocks and alcohols are used. In the work by Fang et al. (2010), the catalyst with the excellent activity ([TMEDAPS][HSO4]) was further studied to observe the effect using different fatty acids and alcohols. Neither the length of the alkyl chains of alcohols nor that of different fatty acids had a sig­nificant effect on the conversion of fatty acids. Plus, the esterification of mixed fatty acids with ethanol is indeed acceptable.

In the meantime, different patterns were observed in the experiment conducted by Ghiaci et al. (2011). The ILs contain sulfonic group, which provides Brqrnsted acid sites for the catalyst. The conversion gives 95.1 wt% biodiesel when methanol was used but decreased to 88.7 wt% as я-butanol was employed. Also, the vegetable oil having higher degree of saturation resulted in lower biodiesel yield compared to the feedstock with the lowest degree of saturation (i. e., canola oil).

Up until now, there is no commercial production of biodiesel using ionic liquid as catalyst. Commercial application of IL is hindered by its prices, which are very costly than conventional solvents. This is reflected by the price of ionic liquids that are usually 2 to 100 times more expensive than the cost of organic solvents (Plechkova and Seddon 2008). Nevertheless, the gap in prices can be bridged by effectively utilizing ionic liquids in the process. Ionic liquids need to be recovered and then used in the subsequent runs after the recycling step. The catalytic activity of ILs also must not deteriorate after the recycling in order to ensure the process becomes economical and viable at larger scale. The continuous use of the catalyst also reduced the problem related to disposal of spent catalyst.

There are several techniques available that have successfully recovered IL from reactants. The most commonly applied method for the recovery is distillation. After removal of glycerol from the lower phase of the biphasic system, vacuum distilla­tion is typically employed to remove other substances from the IL, such as alcohol and water. The recovered IL is later used directly in the new batch of process. The insolubility of IL in esters also helped the separation step becomes more effective. Other methods that can also be employed for the recovery purpose are the super­critical carbon dioxide extraction, membrane separation, and the addition of anti­solvent for crystallizing the IL. In the effort to efficiently use IL as the catalyst in

biodiesel synthesis, it is expected that there is insignificant change in the perfor­mance of recycled IL after appropriate separation and purification steps.

Table 9.2 sums up the changed in recycled IL activity for the esterification and transesterification processes. There was not much change in the catalytic activity of ILs, even after they have been reused for few times.

In some cases, the recycled IL maintained its performance after being recycled without significant change in its performance. Some factors that may have contrib­uted to the decline in the activity are slight loss of the catalyst after each cycle, acidity of the catalyst decreased, and also water content of the oil (Liang et al. 2009; Fang et al. 2010). In addition, the selectivity towards product in biodiesel production remains virtually unchanged when IL is used to catalyze the reaction.

The main aim of various immobilization techniques is to design an efficient lipase — immobilized system for biodiesel production. A number of researches done in this field show that the design of an efficient immobilized lipase is rather a difficult task. Still researchers and organizations worldwide are focused on this task to make an efficient lipase-immobilized system with maximum number of reuses along con­tinuous production of biodiesel. The selection criteria for immobilization technique and carrier are largely dependent on the particular lipase type, the type of reaction system (aqueous, organic solvent, or two-phase system), the process conditions (pH, temperature, and pressure) and the goal of immobilization.

An immobilized enzyme has to execute two essential functions: namely, the non­catalytic functions which are designed to aid separation and catalytic functions that are designed to convert the targeting substrates within a desired time and space. Both the activity and operational stability of immobilized lipase are important. Enzyme activity yield following immobilization does not depend only on losses caused by the immobilization procedure but can be further reduced by mass transfer effects. On the other hand, improved stability of immobilized lipase under process conditions can compensate for such drawbacks, resulting in an overall benefit of lipase immobilization (Cao 2005; Knezevic 2004). Techniques for immobilization have been broadly classified into four categories based on physical and chemical retention, namely, adsorption, covalent binding, entrapment, and encapsulation (Fig. 12.1). A combination of two or more of these techniques has also been inves­tigated (Jegannathan et al. 2008).

Adsorption results in attachment of lipase to the surface of support particles. Attachment of lipase to the support can be by physical adsorption or ionic binding or both. Adsorption technique of immobilization is the easiest and least expensive technique to prepare solid support biocatalyst. The immobilized lipase does not undergo mass transfer limitations and also gives high biodiesel yield in relatively shorter time. The main disadvantage is that the enzyme can be washed off easily from the surface due to weak forces (van der Waals, hydrogen bonds, or hydropho­bic interactions) of attachment.

Microalgae are microscopic, unicellular organisms that have high potential for use in CO2 mitigation and for use as a biomass source due to their high photosynthetic rate. The ability of microalgae to amass high oil content makes them one of the most researched subjects in various fields, including the biofuel, pharmaceutics, and food sectors. Thus, microalgae are the most suitable biological approach to be to seques­ter CO2 because of their characteristics make them suitable for incorporation into many fields. Optimum CO2 utilization by microalgae is related directly to the estab­lishment of optimum conditions for the photosynthesis process, i. e., a sufficient amount of CO2, appropriate nutrients, and adequate light.

The commonly cultivated species of microalgae that are used to achieve this purpose are discussed in previous study (Sarbatly and Suali 2012; Suali and Sarbatly 2012) and rearranged as listed in Table 14.1. As shown in Table 14.1, the preferred CO2 concentration for cultivation is in the range of 5-20% of an air supply that is either pure or enriched with flue gases, including slight amounts of nitrogen oxides and sulphur oxides. Microalgae species that have been tested and deemed to be suit­able for CO2 fixation include Chlorella sp. H84, Chlorella sp. A2, Chlorella soroki — niana, Chlorella vulgaris, Chlorella pyrenoidosa, Spirulina platensis, Emiliania huxleyi, Nannochloropsis sp., and Phaeodactylum sp. Among these, tests have shown that the Chlorella species are preferred for use in mitigating CO2.

Table 14.1 also shows that some species perform better when flue gases are used instead of just air and added CO2 . Further, it has been noted that the cultivation

system performs equally well irrespective of whether flue gases or pure CO2 is used, i. e., there is no adverse effect on algal growth (Negoro et al. 1993). In the work of Cheng et al. (2006), it was shown that a gas stream that had a CO2 concentration of 1% v/v was introduced into a membrane photobioreactor that had a microalgae density of 2.0 x 107 cells mL-1, the CO2 concentration was reduced to 0.015% v/v. This clearly demonstrated that initial density of the microalgae has effect on the CO2 fixation rate. The biomass yield of such a reactor is indicative of the efficiency of the photosynthesis process in the reactor. The biomass yield is proportional to biomass photosynthesis and the CO2 uptake by microalgae. This shows that micro­algae can be considered for mitigating CO2 emissions from power plants while simultaneously producing a useful, renewable product.

The key activities for business development in the biofuel sector at POIC Lahad

Datu are outlined as follows:

• Promotional activities. To intensify promotional activities especially in the bio­fuel sector. The strengths and advantages of POIC Lahad Datu in particular the geographic location (Fig. 2.5) and its deep sea port (Fig. 2.6) are the key attrac­tions for promotion.

• Sourcing of raw materials. Offer of two options in sourcing of raw materials. The first option leaves the investors to look for their source of raw materials and POIC Lahad Datu can assist. The second option is to secure the raw materials through POIC Lahad Datu. Past experience shows that in the case of EFB, the supply is not an issue but the lack of effective demand remains the missing link. This means that investors who are able to start now should be able to secure long­term supply of raw materials.

• Client services. Services rendered to POIC investors include sharing of informa­tion related to the palm oil industries among others and facilitating application of licenses and other documents, industrial linkage, and networking.

• Infrastructural investment. POIC Lahad Datu offers option in participating in infrastructural investment to facilitate the takeoff and operation of the industries investing at POIC Lahad Datu. For example, the planned establishment of an EFB collection center at POIC Lahad Datu is aimed at collecting large quantities of raw or processed (shredded and pressed) EFB from different palm oil mills for further processing into various biomass products by the respective investors. The concept of EFB collection center is to alleviate the logistic problems. In this area, POIC is open to a JV arrangement to operate and manage the facility.

• Research and development. R&D-related activities include information sourc­ing and data collection of oil palm and palm-oil-related statistics, market and techno-economy, technology development, trades, supply and demand of raw materials, and land and sea logistics. POIC Lahad Datu also participates in the R&D projects organized by member partners of Oil Palm Biomass Centre (OPBC)[1] on specific technical, logistics, or social aspects related to the

development of biomass industries towards the production of high-value biofuels and bio-based chemicals. POIC is also in collaboration with a company in China to develop a mechanical oil palm harvester.

2.2 Conclusion

POIC Lahad Datu was established for speeding up the value-adding oil palm downstream industries as the growth engine to accelerate the economic development in the State of Sabah. Since its establishment, POIC Lahad Datu has made significant progress in physical and business development and the formation of industrial clus­ters as programmed for. However, there are challenges ahead to expand its business development in not only the palm oil-based industries but also the palm-based biomass industries with special emphasis given to the latter on biofuels and bio-based chemicals as the new avenues for investment supported under the National Biomass Strategy 2020. It is hope that the innovative approaches as instituted in the strategies for business development could accelerate the investment development to a greater height to meet the expectation.

The properties of OPW fibres make them suitable for the manufacture of composite biopolymers (e. g. plastics). The pores on fibre surface have an average diameter of 0.07 m which gives it a better mechanical interlocking with matrix resin in compos­ite fabrication (Sreekala et al. 1997) . Also, the high cellulose content and high toughness value of OPW make it suitable as composite materials. Lignocellulosic materials such as OPW have the potential to replace synthetic fibres such as aramid and glass fibres in the field of composite material. Though the fibres of lignocellulosic materials have lower density (1.25-1.50 g/cm3) compared to that of fibre glass (2.6 g/cm3), they have high tensile strength similar to those in plastic materials and durable compared to synthetic fibre glass (Agrawal et al. 2000). Also, the high car­bon and nitrogen contents of palm oil liquid wastes make them suitable for the production of biopolymers for composite materials. Nowadays, fibre-reinforced plastic composites (bioplastics) find many applications in the aerospace and auto­motive industries, sports and recreation equipment, boats, office products, machin­ery, etc. (Sreekala et al. 2002).

Polyhydroxyalkanoates (PHA) made from OPW are green biodegradable materi­als widely used as packaging materials though the cost of production is found to be high. However, through improved process technology (Purushothaman et al. 2001), PHA have been synthesised from OPW by various means using different kinds of bacteria and have many applications in the polymer industry. A two-stage process for the production of PHA from POME has been proposed by some authors in which organic acids (such as acetic and propionic acids) were anaerobically pro­duced (Nor’Aini et al. 1999; Phang et al. 2003; Sim et al. 2009) and converted to PHA by a phototrophic bacterium, Rhodobacter sphaeroides IF0 12203 (Hassan et al. 1996) and Comamonas sp. EB 172 (Mumtaz et al. 2010; Zakaria et al. 2008). Other authors have reported the synthesis of PHA from EFB (Dovi et al. 2009).

Polyhydroxybutyrate (PHB) and polylactate (PLA) are other bioplastics that can be synthesised from both the solid and liquid residues of the OPW. During PHB pro­duction, the OPW is fermented to produce acid which is further fermented to produce the polymer using various enzymes. In PLA technology, sugar is produced from the OPW and fermented into l-lactic acids which are polymerised into PLA resins.

OPWs have also been used in many composite materials including OPW/natural rub­ber (NR) composites, OPW/polyvinyl chloride composites, OPW/polypropylene (PP) composites, OPW/polyurethane (PU) composites, OPW/polyester composites, OPW/ phenol formaldehyde (PF) composites, OPW/polystyrene (PS) composites and OPW/ epoxy composites. Polyurethane (PU) composites filled with EFB were prepared using molasses and glycerol-based polyols (Tay et al. 2011) and diphenylmethane diisocya­nate and polyethylene glycol (Rozman et al. 2004) matrices. Both reports concluded that good quality PU composites were produced with higher tensile and flexural properties.

The chemical resistance, void content and tensile properties of EFB/jute (natural rubber) composite have been investigated by Jawaid et al. (2011) to be good. The tensile strength of PPF/natural rubber composites as reported by Joseph et al. (2006) and Jacob et al. (2004) is in accordance to the ASTM D 412-68 Standards. It is inferred from their reports that the tensile strength of PPF/NR composite was higher (7.28 MPa) compared to that of PPF/Sisal/NR composites (3.25 MPa).

Lignin obtained from EFB was used as curing agent in green epoxy composites (Kalam et al. 2005) with the conclusion that the EFB/epoxy composite with 25% EFB-based lignin content gave the optimum properties (Abdul Khalil et al. 2011). Synthesis and physico-mechanical properties of OPW fibre-reinforced epoxy composites have been reported by various studies (Kalam et al. 2005; Bakar et al. 2007; Hariharan and Khalil 2005) with conclusions that they possess better charac­teristics compared to pure epoxy materials.

Benzene diazonium salt has been used in treating OPW fibre to be used as OPW fibre/polypropylene composites (Haque et al. 2009) whose properties are almost similar to coir fibre/polypropylene composites. Other potential applications of PP hybrid composites with OPW include EFB/glass fiber/PU composites (Rozman et al. 2001); EFB/PU, oil palm cellulose/PU composites (Khalid et al. 2008); PPF/ PU composite in which the addition of coupling agent in the makes it a promising bio-product as the addition of fibers to the matrix improved the flexural strength and modulus compared to the pure PP (Goulart et al. 2011); PPF/kaolinite/PU composite (Amin and Badri 2007) and EFB/PU composite (Rozman et al. 2007).

The mechanical properties of benzoylated EFB reinforced poly(vinyl chloride) composites have been studied by Bakar et al. (2007) with improved EFB/PVC matrix interfacial adhesion. Thevy et al. (2008) have reported that the thermogravi­metric analysis (TGA) have not shown any significant changes in the thermal stabil­ity of the composite.

Saline — and alkali-treated PPFs have been used in the synthesis of green compos­ites (PPF/phenol formaldehyde composite) in which the pretreatments increased the thermal stability of the composites compared to untreated PPF (Agrawal et al. 2000). Other authors (Sreekala et al. 2002) have also investigated into the mechani­cal properties of OPW fibre-reinforced phenol formaldehyde composites. Dynamic mechanical analysis of OPW fibre/PF composite carried out by Sreekala et al. (2002) showed that the incorporation of OPW fibre increased the modulus and damping characteristics of the pure sample.

The tensile strength of OPF/glass fibre-reinforced polyester composites increased up to total fibre content of 45% (Abdul Khalil et al. 2007). The weight loss on abra­sion of pure polyester resin is reduced (by 50-60%) by the reinforcement with OPW fibre, whilst the friction coefficient of OPF/polyester composite is reduced by about 23% compared to that of neat polyester (Yousif and Tayeb 2007). The tensile stress of OPF/polyester composites increased slightly upon both acetylation and saline treatments and decreased with titanate treatment (Hill and Khalil 2000).

The modulus of OPW fibre/PS composite is assessed to increase with increase in fibre loading up to 30% whereas the maximum strain and flexural strength decreased (Zakaria and Poh 2002).

Biopolymers such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from EFB (Salim et al. 2011) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) from spent palm oil using Cupriavidus necator (Rao et al. 2010) have also been synthesised using various treatment methods. Alkali treatment is the commonest pretreatment of OPW fibres which is able to improve the fibre-matrix interfacial adhesion.

Transesterification of vegetable oil with methanol in the presence of catalyst is a vital industrialized process and it has been well established. In general, there are three categories of catalysts used to catalyze transesterification reaction for biodiesel pro­duction: alkalis, acids, and enzymes (Ma and Hanna 1999). The alkali and acid cata­lysts including homogeneous and heterogeneous catalysts are commonly used in biodiesel synthesis process. The comparison between homogeneous, heterogeneous, and enzymatic catalyzed transesterification reaction was shown in Table 10.2.

Hydrolysis of olive oil was carried out with immobilized lipase with and without glutaraldehyde cross-linking. The reaction mixture which consisted of 30 ml of olive oil, 47.6 ml of я-hexane, 2.4 ml water, and 4 g immobilized lipase was incu­bated at 40°C, 200 rpm in a stirred tank reactor. Samples were withdrawn at specific time intervals and analyzed for fatty acids. The free fatty acids were estimated using NaOH by standard titimetry method. The results are depicted in Fig. 12.5f. The cross-linked lipase showed better hydrolytic activity as compared to the non-cross — linked enzyme. These results suggest that the proposed method of lipase immobili­zation has got profound potential in biofuel industry.

Soh Kheang Loh and Yuen May Choo

Abstract The R&D on biofuels in Malaysia was first commenced in 1980s and since then its commercialization progressed at a slow pace with many uncertainties. Until recently, it has gained much attention and popularity not just in Malaysia but in many parts of the world, mainly rooted in some advantages it has over fossil fuels. There are at least three different generations of biofuels, i. e. first-generation biofuels, second-generation biofuels and third-generation biofuels.

Keywords Biofuel • Palm oil • Palm biomass • Biogas • Palm biodiesel

1.1 Introduction

4.3.1 L-Cysteine (Biomass Model Sample)

The measurements were conducted for 2 min at each temperature. L-Cysteine decomposes and releases several species as shown below:

decomposition

L-cysteine ^ H2S, CO, CO2, SO2, SO3, etc.

Fig. 4.2 SIM (Selected Ion Monitoring) traces of (a) m/z 35 [CO + Li] +, (b) m/z 51 [CO2 + Li] + and (c) m/z 41[H2S + Li]+ at different temperatures (Alif et al. 2011)

Figure 4.2 shows SIM traces of m/z 35 [CO+Li]+, m/z 51 [CO2+Li]+, and m/z 41[H2S + Li]+ at different temperatures.

Starting from 250°C, these gases tend to increase in evolving amount and reach the highest concentrations at 380°C. When Ca(OH)2 was added, the formation of CO (Fig. 4.2a) was suppressed as well as CO2 (Fig. 4.2b) and H2S gas (Fig. 4.2c). These results indicate that these environmentally burdening gases can be suppressed by adding Ca(OH)2. The similar results were reported in another paper, using Na2CO3 as an alkaline additive (Ishida et al. 2009). It should also be note that under supercritical condition, water will act as an oxidizing agent for carbon and heteroat­oms in biowastes to produce their oxides and oxoacid.

The alkaline reagent neutralizes the acids and traps them as their anions in the liquid phase. Consequently, pure hydrogen can be produce with freedom environ­mental load gases CO2 and toxic acids.