The government support on renewable energy (RE) can be seen under the 8th Malaysia Plan with the introduction of 5-Fuel Policy (2001)—implying 5% of RE in energy mix but only achieved 1.8% under the 9th Malaysia Plan. Under the 10th Malaysia Plan, RE deployment was better facilitated with the release of RE policy and action plan (SEDA 2011).

The policy sets a target of achieving 2 GW RE by 2020, i. e. 10% or 2,065 MW of the national grid electricity. Of this, about half of the electricity will be attainable from oil palm biomass and biogas from palm oil mill effluent (POME). Thus, the main contributor for renewable energy is biomass — and biogas-based energy, and these can be potentially generated from the palm oil industry.

Assuming 100% of one form of oil palm biomass, i. e. empty fruit bunches (EFB) and POME, are utilised, the maximum potential RE derived from them is about 1,500 MW. To date, four palm-based biomass power plants and two biogas plants (Table 1.2) are connected to the national grid with total installed capacities of ~43 MW (Ministry of Energy, Green Technology and Water 2011).

Besides palm-based RE, other locally produced indigenous resources that can be exploited are forestry residue (wood waste), municipal solid waste (MSW), agricul­ture residues (rice husk, rice straw, rubber by-product, sugarcane bagasse, animal manure), energy crops (jatropha, algae) and other non-biomass-based RE such as hydro, solar, wind and geothermal.

Other policies that were aligned to support RE are:

1. Small Renewable Energy Power Programme (SREP) (May 2001)

2. National Biofuel Policy (March 2006)

3. Malaysian Biofuel Industry Act (July 2007)

Keat Teong Lee and Cynthia Ofori-Boateng

Abstract Conversion of agricultural wastes into biofuel and other value-added bio-products has not only benefited the environment but also helped reduce the dependency on natural resources leading to improved lifestyle of humankind. Palm oil wastes (OPW) comprising both solid and liquid residues from the palm oil industry are among the most abundant agricultural wastes in the world. The ineffi­cient method of disposal and management of OPW has necessitated the need to recover value-added products from them. This study reviews the vital characteris­tics of OPW which present them suitable for the synthesis of value-added bio­products. Simultaneous production of palm oil fresh fruit bunches (FFB) and the utilisation of the plantation wastes for food and animal feed with integration of animal husbandry in the palm oil plantation are discussed. Moreover, the simulta­neous conversion of FFB into palm oil and the utilisation of the mill’s residues for value-added bio-products are also discussed.

Keywords Value-added bio-products • Palm oil wastes • Palm oil • Palm oil

5.1 Introduction

Due to uncontrollable global rise in population growth, there has been high demand for fuel, food, medicine, chemicals and other consumable products which have necessitated the growing interest in new technologies of transforming wastes into value-added bio-products. The conversion of agricultural residues such as palm oil wastes (OPW) into bio-products would help solve the issues of energy crisis, waste

K. T. Lee (*) • C. Ofori-Boateng

Lignocellulosic Research Group, School of Chemical Engineering, University Sains Malaysia, Seri Ampangan 14300 Penang, Malaysia e-mail: chktlee@eng. usm. my; cyndykote@yahoo. com

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels,

DOI 10.1007/978-1-4614-6249-1_5, © Springer Science+Business Media New York 2013 disposal and high phytochemical costs all over the world, hence achieving the holistic approach towards zero-waste strategy. This approach, for instance, has been adopted and applied by Haslenda and Jamaludin (2011) who have developed a framework called industry to industry by-product exchange network (I2IBEN) which is able to solve the problem of waste generation and management in the palm oil refinery. This framework is able to raise the palm oil refinery’s gross profit to MYR182, 893 when the by-product revenue, packaging cost, delivery cost and all the supply constraints are considered.

The palm oil (Elaeis guineensis Jacq.) is a single-stemmed tropical and agro-industrial tree which belongs to the palm family (Arecaceae) and whose fruits produce mainly palm oil as the most consumed edible oil in the world (Kelly-Yong et al. 2007). The huge demand for palm oil (with about 27% share of the total world’s oils and fats production) worldwide has caused an increase in oil palm production which has further facilitated the generation of large amount of OPW. These biomass residues are readily available and in urgent need of an efficient utilisation and effective means of disposal.

A hectare of palm oil plantation on dry weight basis generates about 50-70 tonnes of OPW annually (Salathong 2007). The main type of OPW includes empty fruit bunches (EFB), palm-pressed fibre (PPF), palm oil trunks (OPT), palm oil fronds (OPF) and palm oil mill effluent (POME), which are further discussed in this review. The world’s total annual production of OPW is estimated at about 184 million tonnes with about 5% annual increment (Global oils and fats business magazine 2007). The palm oil industry generates its wastes mainly in the form of lignocellu — losic materials from the plantation and the palm oil milling processes. The extrac­tion of 1 tonne of crude palm oil (CPO) requires about 5 tonnes of fresh fruit bunches (FFB) which generates about 1.15 tonnes of EFB and 2.45 tonnes of palm oil mill effluents as residues (Corley and Tinker 2003). The processing of an FFB (weighing 20-30 kg) generates about 20% of CPO, about 25% nuts (comprising about 5% kernels, 13% fibre and 7% shell) and about 23% EFB (Yusoff 2006; Corley and Tinker 2003). These figures keep rising yearly as the demand for palm oil increases, and only about 10% of the generated OPW is utilised with the remaining 90% creat­ing environmental burdens as their current disposal methods are unsafe. The devel­opment of new bio-products from OPW has gained much attention recently, and the simultaneous production of these products within the palm oil industry would help boost the economy and maintain sound environment.

The potential applications of OPW as raw materials for the production of value-added products such as sugar (Rahman et al. 2006; Chin et al. 2011; Zahari et al. 2012), phytonutrients (Ahmad et al. 2009; Ng and Choo 2010; Sasidharan et al. 2012), bioplastics (Mumtaz et al. 2010), biochemicals (Misson et al. 2009; Burham et al. 2009), herbal medicines (Sasidharan et al. 2010; Rosalina Tan et al. 2011) and biofuel (Jung et al. 2011; O-Thong et al. 2012) have been reported.

This review objectively elaborates on the potentials of utilising wastes through modern technological methods in transforming OPW into value-added bio-products as a way of enhancing sustainable utilisation and management of wastes from the palm oil industry as well as increasing the financial viability of the palm oil.

In general, the reaction proceeds according to the following stoichiometric equation as follows (Fig. 8.2):

CH2-O-H

O

catalyst

O

CH2-O-C-R

Triglyceride (oil) methanol Glycerol mixture of methyl ester

Fig. 8.2 Stoichiometric equation of transesterification process for biodiesel production

Since the transesterification reaction is reversible, an increase in the amount of one of the reactants will result in higher FAME yield, and at least three molar equivalents of methanol are required for the complete conversion of the oil to its corresponding FAME.

Figure 8.3 presents the result for performance of different lipase in their free or immobilized form synthesizing biodiesel in batch process at a low temperature of 30°C. Among the lipases, Novozyme 435 (immobilized lipase from C. antarctica) displayed the highest methanol affinity because the lipase gave the highest FAME yield at 1:1-4:1 methanol to oil molar ratio. This is in agreement with the previous finding that Novozyme 435 showed high activity in methanolysis reaction com­pared to other alcoholysis reaction (Hernandez and Otero 2008). Throughout the methanol to oil molar ratio studied, Lipozyme TL IM (immobilized lipase T. lanu — ginosus) and free lipase C. antarctica achieved the second highest FAME yield, while the methanolysis reaction catalyzed by free lipase R. miehei gave the lowest FAME yield. Optimum FAME yield at 4:1 methanol to oil molar ratio was an advan­tage because high methanol to oil substrate molar ratio of more than 3:1 was required to shift irreversible transesterification for high conversion, to minimize the diffusion limitations, and to keep the glycerol formed in solution during the reaction (Noureddini et al. 2005; Hernandez and Otero 2008). The 4:1 methanol to oil molar ratio was not an inhibition factor to lipases; thus, the differences in FAME yield achieved between each lipases were due to lipase catalyzing specificity to the CPO transesterification. In addition, the -ert-butanol solvent was used to completely

dissolve methanol and CPO into the reaction mixture. This minimized the adverse effects of methanol and glycerol inhibitions to all types of lipases. Since lipase was not inhibited at 4:1 methanol to oil molar ratio, higher methanol to CPO can be used to encourage even greater FAME productivity.

Then, study of thermal stability of different lipase was carried out and presented in Table 8.4. Maximum FAME’s yield was attained at 30-40°C regardless of types of lipases used. The lipases were thermally deactivated at high temperature of 50-60°C. The immobilized lipases from T. lanuginosus, C. antarctica, and R. miehei were susceptible to thermal deactivation during the transesterification with alcohols. The catalyzing activity was the highest at the range of 25-35°C, and the lipase activity decreased at temperature above 40°C (Rodrigues et al. 2008). The results revealed that all immobilized lipases of T. lanuginosus, C. antarctica, and R. miehei had higher thermal resistant than the free lipases. The methanolysis cata­lyzed by Novozyme 435 (immobilized lipase C. antarctica) achieved high FAME yield (61.19-68.12%) under 30-60°C operating temperature, while for lipase CALB L (free lipase C. antarctica), a minimum yield of 33.22% was observed. The same trends were observed for lipase T. lanuginosus. FAME yield of 54.85-63.14% was observed within 30-60°C operating temperature for Lipozyme TL IM (immo­bilized lipase T. lanuginosus) and minimum yield of 35.38% for lipase TL 100L (free lipase T. lanuginosus). Therefore, the adverse effects due to thermal denatur — ation were less pronounced to the immobilized lipase, and the stability of immobi­lized lipase subjected to excessive heat treatment was largely preserved. The final mixture of biodiesel is usually composed of mono-alkyl esters, alcohol, and free fatty acids, and tri-, di-, and monoglycerides were then validated. Therefore, EN 14214 and ASTM D 6751 biodiesel standards are employed as references for the quality control of FAME produced from CPO transesterification.

CPO that was used as triglyceride feedstock and pure FAME that was sampled at 4 h were analyzed for chemical properties and physical performances (Table 8.5). Most of the physical and chemical properties and fatty acid compositions for both

CPO Reaction product3 at 4 h EN 14214 Description Value Description Value Limits Physical properties 1. Density 0.89 g/ml 1. Density 0.85 g/ml 0.86-0.90 g/ml 2. Kinematic 38.83 mm2/s 2. Kinematic viscosity at 40°C 7.93 mm2/s 3.5-5.0 mm2/s viscosity at 40°C Chemical properties 1. Iodine value 53.8 meq/kg 1. Iodine value 53.9 meq/kg 2. Acid value 6.4 mgKOH/g 2. Acid value 5.8 mgKOH/g 0.50 mgKOH/g (max) 3. Saponification value 191.7 3. Saponification value 184.7 — 4. Water content 0.035% v/v 4. Water content 0.050% v/v 0.050% v/v (max) 5. Free fatty acid 2.91% wt/wt oil 5. Free fatty acid 2.67% wt/wt oil — 6. Fatty acid compositions: 6. Fatty acid compositions: Myristic acid. 04:0 1.46% Myristic acid. C14:0 1.25% — Palmitic acid. 06:0 38.76% Palmitic acid. C16:0 40.92% Stearic acid. 08:0 4.00% Stearic acid. Cl8:0 6.03% Oleic acid. 08:1 43.80% Oleic acid. Cl8:1 42.88% Linoleic acid. 08:2 11.92% Linoleic acid. C18:2 8.92% 7. Acylglycerol compositions: 7. Acylglycerol compositions: Monoglyceride 0.38% wt/wt oil Monoglyceride 0.6% wt/wt oil 0.80% wt/wt oil Diglyceride 6.58% wt/wt oil Diglyceride 0.15%wt/wt oil 0.20% wt/wt oil Triglyceride 89.48% wt/wt oil Triglyceride 0% wt/wt oil 0.20% wt/wt oil (max) 8. Fatty acid methyl ester 0% wt/wt oil 1. Fatty acid methyl ester 2. Fatty acid methyl ester compositions: 96.51% wt/wt oil 96.5% wt/wt oil (min) Myristate ester. C14:0 1.19% — Palmitate ester. Cl6:0 41.2% Stearate ester. 08:0 4.43% Oleate ester. 08:1 43.3% Linoleate ester. 08:2 9.88% “Reaction product at 4 h was obtained after evaporating tof-butanol solvent at 85°C for 1 h and followed by separating glycerol from reaction mixture using centrifuge

CPO and FAME samples were at the same values except kinematic viscosity, water content, and acylglycerol compositions of tri-, di-, and monoglycerides. Kinematic viscosity for FAME sample was 80% less viscous than the CPO mainly due to the high presence of FAME yield, 96.15% in the mixture. The high viscosity observed in CPO was correlated to the content of unreacted triglycerides. Since kinematic viscosity for FAME sample was slightly higher than the EN standard, complete conversion in CPO transesterification was expected to further improve the kine­matic viscosity to fall within the limits. The water content in FAME sample that was mildly increased from 0.035 to 0.05% v/v may signify minimum level of esterifica­tion on FFA occurred in the system. The 0.05% v/v water content in FAME sample complied with EN standard. The quality control of water content was important since water could promote microbial growth, leads to tank corrosion, participates in the formation of emulsions, and causes hydrolysis or hydrolytic oxidation. Most of the acylglycerols in CPO that were converted to FAME with traces amount of di — and monoglycerides were detected in the FAME mixture, and these acylglycerol residues were within the EN quality control. Overall, the biodiesel specifications for FAME sample such as ester content, density, water content, mono-, di-, and triglyc­erides compositions with values of 96.15%, 850 kg/m3, 0.05% v/v, 0.65%, 0.15%, and 0%, respectively, were all well within the limits in standard EN. Since the hydrolysis of ester linkages was kept at the minimum level in the study and allowing the highest extent of transesterification process, FFA content in CPO was not con­verted to FAME and thus caused the acid value 5.8 mg KOH/g exceeding the EN limit of 0.5 mg KOH/g (Sim 2011).

Another type of lipid source that could be used is waste cooking palm oil (WCPO). Figure 8.4 shows the comparison of FAME’s yield between the waste cooking palm oil (WCPO) with the refine palm oil (RPO). The trend for WCPO and the RPO is almost the same. The reaction rate of WCPO was almost the same with

RCO at the beginning of reaction time up to 4 h. While at the final, the FAME yield of RCO was higher than that of WCPO. The highest FAME’s yield of 88 and 96% was achieved for WCPO and RPO, respectively.

Table 8.6 presented results obtained after conducting experimental in batch for production of biodiesel from WCPO. It showed that Novozyme 435 was used for the transesterification of waste cooking palm oil with methanol in batch system. Novozyme 435 remained active in tert-butanol as the reaction media (Halim et al. 2009). The optimum tert-butanol to oil volume ratio and methanol to oil molar ratio were achieved at 1:1 and 4:1, respectively. The optimum Novozyme quantity was 4% based on oil weight.

Lastly, Cerbera odollam oil was tested for production of biodiesel using enzy­matic reaction. The transesterification reaction was carried in batch, and optimiza­tion study was conducted by using statistical method using design of experiment (DOE) software. The optimum conditions found are 4.1 w/w% enzyme based on oil weight, 1:5.1 oil to methanol molar ratio, 0.51:1 solvent to oil volume ratio, tem­perature 40°C, and agitation speed 200 rpm. The value of FAME yield obtained from experiment was compared with the one predicted by DOE as shown in Table 8.7 . The predicted response value from DOE software is 95.09%, and the
optimized FAME yield from experimental study was 94.75%. An error of ±2.43% for FAME yield value under 95% confidence levels provides promising result of 94.75 ± 2.43% (Rahaman 2011).

This section will illustrate two feedstock examples that are abundant in the South East Asian region: crude palm oil and crude coconut oil. Table 11.3 shows the typical constituents of crude palm oil. A new processing configuration using the ET Process® is proposed in Fig. 11.3. There is no need to use RBD (refined, bleached, deodorized) palm oil for the ET Process®. Degummed, crude palm oil can be directly used as the feedstock. The product leaving the ET Process® consists of pure glycerol and pure palm-based biodiesel. Palm-based biodiesel can be used as a summer biodiesel. Phytochemicals, like tocopherols and carotenes, can be separated from biodiesel, for instance, via short-path distillation. Phytochemicals can be sent downstream to increase their concentration or be further separated. Biodiesel distillate, which is a colourless product, can be separated into two major products: methyl palmitate (C16:0) and methyl oleate (C18:1). The latter can be used as winter biodiesel. The former can be used as a raw material for the surfactant industry or be further purified to obtain pure methyl palmitate, which can be reacted with the pure glycerol prod­uct to produce pure glycerol monopalmitate. Fatty acid methyl myristate can be lumped into the winter biodiesel product or sold independently.

Glycerol monopalmitate is a monoglyceride widely used in food, cosmetics and pharmaceuticals. It can be applied as a lubricant in implant delivery devices, such as intraocular lens inserters (Vanderbilt and Tsou 2005), and as stabilizers and emulsi­fiers in suppositories (Lee 2007). It is used as a preservative in bread and potato starch products because of its ability to complex with amylase (Tufvesson et al. 2001;

Table 11.4 Typical composition of crude coconut oil (Hui 1996)

Twillman and White 1988). Glycerol monopalmitate has also been found to inhibit P-glycoprotein activity, which is a key mechanism in multidrug resistance in tumour cells (Konishi et al. 2004). It (1-monopalmitin) was found to attenuate multi-drug resistance protein 2, which could improve oral drug delivery, as well (Jia and Wasan 2008). In most pharmaceutical applications, pure monoglycerides are highly desired. The monoglyceride products derived from esters of the ET Process® can be obtained with a higher than 99.5 wt% purity. These can also have wide applications as raw materials for bio-based polymers.

Compared to the current chemical process, no refinement of feedstock is involved. There can be big savings when oil feedstock having high FFA content is used. Only a degumming step is required for crude palm oil in the ET Process®. Furthermore, pure glycerol is produced. After undergoing decolorization and puri­fication, technical grade or pharmaceutical grade glycerol is produced in a simple way. The phytochemical co-products are important to boost profits and it is a feature unique only to the enzymatic process. This is another reason why it is incomparable to the chemical approach.

Table 11.4 displays the typical constituents of crude coconut oil. The fatty acid profile is very different from that of palm oil. Figure 11.4 shows the possible pro­duction configuration using the ET Process®.

Degummed, crude coconut oil is first forwarded to the ET Process®, and then the products are separated into a series of units. A mixture of methyl stearate (C18:0) and oleate (C18:1) can be used as winter biodiesel. A mixture of C14 and C16 esters can be used to manufacture methyl ester sulfonates (MESs). The C12 ester can be used as surfactant materials for fatty alcohol production. The C8 and C10 esters can be separated into pure products and further converted to high value-added products widely used in food, pharmaceuticals, cosmetics and general industries. These two types of monoglycerides have either antibacterial or antimicrobial properties. In this case, biodiesel is treated as a by-product.

The effect of extraction on ethanol production can be seen significantly from Fig. 13.5. Extracted seaweed produced higher ethanol percentage compared to non — extracted seaweed. Extracted seaweed yields 9.58% v/v of ethanol compared to 3.33% v/v of ethanol produced from non-extracted seaweed.

This is because by extraction (i. e. boiling the seaweed in hot water at 100% for 2 h), carbohydrates such as polysaccharide were released from the seaweed and dissolved in the slurry (Lin et al. 2000). In macroalgae biomass, it is known that it contains different types of carbohydrate mostly stored in the algae cell wall (Hu et al. 1998). The carbohydrates must be released and converted into simple sugars in order for the microorganisms to utilise these simple forms for bioethanol pro­duction (Philippidis and Smith 1995; Nguyen et al. 2009; Adams et al. 2009).

Fig. 13.5 Ethanol percentage for non-extracted and extracted seaweed

Hence, this makes the biomass pretreatment a crucial step. Without extraction, most carbohydrates are entrapped in the seaweed and not readily available for hydrolysis and subsequently for yeast to digest.

Figure 13.6 showed the comparison of the reducing sugar concentration in the slurry with or without extraction. The concentration of reducing sugar before fer­mentation was higher for experiment with extraction (8.10 mg/mL) compared to the one with no extraction (3.59 mg/mL). The concentrations of reducing sugar after fermentation for both experiments were similar, with extraction (1.96 mg/mL) com­pared to the one with no extraction (2.11 mg/mL). This showed that more sugar was utilised in the extracted sample (i. e. 6.14 mg/mL). Therefore, at this point, the extracted seaweed was expected to produce more ethanol compared to the non — extracted seaweed.

2.2.1 Establishment and Administration

POIC Lahad Datu was established in January 2005 as POIC Sabah Sdn Bhd. It is the first comprehensive palm oil industrial cluster in the world. Owned by the State Government of Sabah, it is managed under the Chief Minister’s Incorporated and, operationally, by the State Ministry of Industrial Development.

2.2.2 Objectives

The key objectives of POIC Lahad Datu are to create jobs and investment opportu­nities, to reduce dependency on the upstream segment of resource-based industries, to diversify the economy by introducing value-adding and knowledge-based industries to Sabah, to increase competitiveness of the palm oil industry in realizing the upstream and downstream potentials, and to bring economic and industrial development to Sabah in order to be at par with Peninsular Malaysia. It does all these by providing the required basic and advance infrastructure.

5.3.1 Food and Animal Feed

Though OPWs have been considered as nonedible, the potential of producing highly nutritious foods (for both humans and animals) as well as vitamin supplements has been reported in recent studies. The fibres of the OPW (mostly EFB, OPT and OPF) comprise mainly cellulose (about 25-50%), hemicellulose (about 20-35%) and lig­nin (about 15-25%) which are readily convertible to carbohydrates and sugars such as glucose, sucrose and fructose for various applications in the food industries.

EFB is reported to compose of about 24% xylan (a sugar polymer made of pen­tose sugar called xylose) which can serve as a substrate for the production of sweet­ening agents such as xylitol, sorbitol, and lactitol by catalytic hydrogenation (Wyman 1994; Silva et al. 1995). Xylitol is used extensively in the food and phar­maceutical industries as sugar for diabetic patients, as supplements in energy drinks and as anticariogenic agent in toothpaste formulations for the prevention of cancer (Makinen 1992) . Aqueous sorbitol solutions are hygroscopic thus useful in the applications of humectants and softeners in the food and pharmaceutical industries (Gliemmo et al. 2008). Recent studies have reported the hydrolysis of xylose and glucose from sulphuric acid-pretreated EFB with concentrations of 31.1 and 4.1 g/l, respectively (Rahman et al. 2006) , steam-pretreated OPF with glucose yield of 92.78 wt% (Goh et al. 2010), steam-pretreated EFB with glucose yield of 209 g/kg EFB (Saleha et al. 2012), the juice from the OPF (Fazilah et al. 2009) with glucose concentration of 53.95 ± 2.86 g/l, thermally treated OPT (Ho et al. 2007), etc. OPT juice has been found by Chin et al. (2011) to have a higher glucose conversion yield compared to those for rubberwood sawdust and mixed hardwood sawdust. The highest yield of monomeric sugar (70% of total carbohydrate content) was found in EFB (41.82%, w/v) pretreated by enzyme and saccharified for 120 h (Rashid et al. 2011). Food flavouring such as vanilla essence can be extracted from EFB (Ibrahim et al. 2008).

PPF is used as fibre enrichment agent for the manufacture of bread which gives it a heavier consistency than normal white bread (Kamarun Zaman 2008). Fibre content of 6.1 g/100 g serving has been used in a formulation of the palm fibre bread which has the same fibre content as most whole meal breads. Pre-hydration of OPW fibres was reported to improve dough water absorption and high fibre bread loaf volume (Kamarun Zaman 2008). Again, OPT fibres, due to its high water absorp­tion rate (without congealing) coupled with its capability of withstanding high tem­peratures during food processing, have been successfully used as food fibre in yoghurt, pastries and bread in place of wheat. Currently, Malaysia produces special cereals from OPT fibres using patented process by the Sukhe International Sdn Bhd. Thus the transformation from wastes to wealth is highly feasible. PKC contains valuable dietary protein (14.5-19.5 g/100 g) (Alimon 2004) which can be commer­cially isolated (by enzyme-assisted extraction in alkaline medium with an optimum yield of 11.91 g/100 g) and concentrated for various applications in the food industry (Chee et al. 2012). PKC is also used as a substrate in solid-state fermentation (SSF) for the production of enzymes such as tannase (Sabu et al. 2005), phytase (Ramachandran et al. 2005), alpha amylase (Ramachandran et al. 2004), and P-mannanase (Ong et al. 2004). Ariffin et al. (2008) have also reported the feasibil­ity of producing an enzyme called bacterial endoglucanase from EFB for different applications in the food and nutraceutical industries.

Flour prepared from defatted PKC was used as a substitute for wheat bran for the preparation of dietary fibre-rich wheat cookies and bread. These cookies and bread from PKC showed better nutritive value (e. g. lower starch content) than those for normal wheat bread and cookies (Pacheco de Delahaye et al. 1994). The feasibility of monoacylglycerol production from PFAD as additives in bread and pastries has also been demonstrated by Junior et al. (2012) with a production yield of 73%.

The low protein and high fibre contents of OPF make it a good potential source of feed for many classes of herbivorous animals like cattle, buffaloes, sheep, etc. (Dahlan et al. 2000). The potential of using PPF for ruminant production has been examined by Abu Hassan et al. (1996) to be feasible especially when it is chemi­cally treated and well formulated to improve its nutritive value. Various pretreat­ment methods have been used to improve the quality of PPF to enhance its biodegradability and digestion in ruminants (Abu Hassan et al. 1996; Dahlan et al. 2000). Experimental goats were given OPF as a raw feed whose organic matter digestibility increased through ensiling, while pelleting increased the intake rate significantly (Dahlan et al. 2000; Kawamoto et al. 2001). PPF treated with sodium hydroxide has been reported by various studies (Kawamoto et al. 2001; Jelan et al. 1986) to increase its dry matter digestibility from 43.3% to 58.0% but detrimental to its palatability. Low-pressure steaming of OPF at 10 kg/cm2 for 20 min followed by oven drying at 60°C for 48 h have been reported by Bengaly et al. (2000) to sig­nificantly improve its nutrient degradability. Urea treatment (3% and 6%) had a negative effect on digestibility, but the addition of up to 3 g/kg of urea to steam — treated OPF increased its intake and digestibility in goats (Abu Hassan et al. 1996). However, in sheep, coupling urea treatment with heat treatment of OPF showed better intake and digestibility up to 16 g/kg (Bengaly et al. 2010).

Diets containing about 50% OPF which were ministered to cattle did not show any nutritional disorders as side effects (Abu Hassan et al. 1996). Goto et al. (2002) have reported low contamination risks in OPF as they are poor medium for aflatoxin (a food contaminant) production. Though much research have not been done on the use of EFB as feed for animals, Abu Hassan et al. (1996) have concluded that EFB processed into pellets may increase the nutritional value of the feed. The sustainable utilisation of fibres from the OPF, PPF and EFB is achieved when they are made into pellets. For instance, unpelleted or untreated OPF petioles are not palatable to goats (Dahlan et al. 2000). Cattle fed on OPF pellets measuring 9 mm in diameter and 3-5 cm in length with 33.3% total digestible nutrients gained 0.93 kg/day (Asada et al. 1991).

In order to maintain the availability of animal feed all year round, fibres from the OPW can be used in place of grass molasses and straw especially during the dry season when they get dried up. Also, the use of OPW fibre may save a lot of time used in grazing for ruminants (Abu Hassan et al. 1996). The integration of livestock rear­ing in oil palm plantation which result in internal food chain (i. e. OPFs, EFBs, OPLs, PKC etc. are used to feed the animals whilst the dung from the animals are also used to fertilize the plantation’s soil) may provide cost effective utilization of OPW.

Mixtures of OPW such as OPF (about 30%) and PKC (about 70%) which were administered to cows as feed increased their milk production more than the feed containing only grass (Abu Hassan et al. 1996). Rabbits fed on 50% pelleted OPF and 50% concentrate gained about 28.3 g/day (Dahlan et al. 2000). Abu Hassan et al. (1991) have shown that OPT fibre is a good source of roughage for ruminants compared to rice straw.

Biodiesel can be produced from oils or fats through transesterification in the pres­ence of catalyst and alcohol. However, this conventional method faced several dif­ficulties. This includes the use of excess alcohol to push the chemical equilibrium of transesterification towards fatty acid alkyl esters formation and extreme operating conditions, especially for those involving heterogeneous catalyst.

Advances in processes and technologies are studied to address these barriers to ensure more sustainable and enhanced production efficiency. The development of advanced technologies to improve the processes and contribute towards more effective biodiesel production is discussed in the following subsections.

Figure 9.6 shows some of the novel processes that have been applied for improv­ing the efficiency of biodiesel process.

Immobilization of lipases is gaining importance due to a broad variety of industrial applications they catalyze. In this study, lipase from B. cepacia (Pseudomonas cepacia) was first cross-linked with glutaraldehyde followed by entrapment into hybrid matrix of alginate and к-carrageenan polymers. The effect of various param­eters like pH, temperature, reusability, enzyme leakage, solvent, and storage stabil­ity on immobilized lipase was studied.

Early membrane contactors were developed from microporous propylene fibre, which includes polypropylene (PP), polytetrafluoroethylene (PTFE), and polyvi — nylidene fluoride (PVDF). These materials have been used dominantly to make membrane contactors for the removal of gases in gas-liquid phase separation processes and absorption processes. While most membrane contactors have a porous structure, some have a more dense structure.

The use of PP made membrane contactors suitable for CO2 removal from the gas-liquid phase (Dindore et al. 2004). The main reason that most membrane con­tactors were made from hollow-fibre PP is that the contactor has a fixed and well — defined gas-liquid interfacial area, which resulted in easy evaluation of the hydrodynamic situation on the liquid side of the membrane contactor (Dindore et al. 2005). According to Khaisri et al. (2009), the effectiveness of membrane con­tactors for removing CO2 from the liquid phase through absorption can be ranked as PTFE > PVDF > PP.

The productivity and selectivity of PP also was reported to be better than poly­phenylene oxide (Simons et al. 2009). However, PP has the lowest absorption rate compared to PTFE and PVDF, but PP continues to be the most applied membrane contactor in the industry due to its efficiency for capturing and removing CO2 the liquid phase (Zhang et al. 2008; Agrahari et al. 2011; Lv et al. 2012).

The application of PP in gas-liquid separation processes required extra care due to its extreme sensitivity to small variations in the feed pressure that could cause severe performance losses. As shown in Simons et al. (2009), high liquid losses are observed for the PP fibres, especially at elevated temperatures. This issue is not a hindrance in CO2 supply to microalgae culture because it is a low-temperature operation.

The PTFE membrane has been reported to be effective for use in the ozonation of wastewater. In comparison with PDVF, PTFE gave more a stable and higher flux (Bamperng et al. 2010). The PTFE also was reported to be effective for use in gas-liquid separations in microgravity conditions. The O2 produced from the bio­logical life and the required CO2 capable to evolve and exchange within the PTFE membrane (Farges et al. 2012). PVDF has been reported to be less effective, and the CO2 flux decreases as the operation period increases. Among the reasons that were identified was the formation of liquid droplets on the gas side of the mem­brane (Zhang et al. 2008).