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Use of Oil Palm Biomass for Polyhydroxyalkanoates Biopolymer Production

*Artikel diterbilkan dalam Bahasa Inggeris dan tidak diterjemah ke dalam Bahasa Melayu*
*Artikel telah diterbitkan dalam majalah INTROPica Isu 14. Januari-Jun 2017*

 

By: Hidayah Ariffin1,2 and Mohd Ali Hassan2

 1Laboratory of Biopolymer and Derivatives, Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, MALAYSIA
2Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, MALAYSIA

Summary

The palm oil sector generates 80 million dry tonnes of biomass in Malaysia alone. There is increasing potential to utilise oil palm biomass, which are available at the palm oil mills as business-as-usual without any additional collection costs, for higher-value uses such as biopolymers. The National Biomass Strategy 2020 estimated that 12 million dry tonnes of oil palm biomass will likely be utilised for wood products and bioenergy. An additional 20 million tonnes could be mobilised for use as biofuel pellets and bio-based chemical industries. Since many of the biomass technologies are fast maturing and becoming more economically feasible, the trend for oil palm biomass utilisation to value-added and sustainable products such as biopolymers will continue to rise.

 Keywords: Oil palm biomass, value-added products, biopolymers

 Introduction

It is estimated that 11% of Malaysia’s gross national income (GNI) is contributed by the agriculture sector, and from that figure, more than half (8%) is contributed by palm oil sector. Malaysia has been well recognized as the leader of palm oil export globally due to its favourable agro-ecological conditions for crop growth and development. In December 2012, a total area of 5.1 million hectares was planted with oil palm trees which yielded nearly 100 million tonnes of fresh fruit bunch (FFB) and were further processed to produce 20 million tonnes of crude palm oil (CPO) (MPOB, 2013). This large production of palm oil resulted in huge generation of waste and wastewater from the palm oil industry. It was reported that four kg of solid biomass is generated for every kg of palm oil produced. On the other hand, palm oil mill effluent (POME) is generated at 50 % of the total amount of FFB processed (Yacob et al., 2006).

There have been many studies on the utilization of solid and liquid biomass from palm oil industry for biopolymers production. By adopting the research outcome in the industry, sustainable palm oil production could be created as the biomass will not only be discarded efficiently, but it may also contribute to extra income to the industry and give positive impact socially by creating new job opportunities. Furthermore, efficient utilization of oil palm biomass for such bioproducts will also contribute to sustainable production of energy and materials since renewable feedstock are being used.

 Oil palm biomass

Oil palm biomass are by-products from palm oil industry, which cover both by-products from the oil palm plantation and palm oil mills. Six types of oil palm biomass have been recognized from the industry, with palm oil mill effluent (POME) as the only liquid biomass. Table 1 shows the types of oil palm biomass, production site, annual generation of biomass and current uses.

 Table 1. Oil palm biomass (data adopted from National Biomass Strategy 2020)

Type of biomass

Production site

Amount generated*

(million tonnes)

Availability

Current uses

 

Oil palm fronds (OPF)

Plantation

46

Daily

Discarded at the plantation for soil mulching

Oil palm trunks (OPT)

Plantation

14

At the end of plantation lifecycle (every 25 years)

Discarded at the plantation

Oil palm empty fruit bunch (OPEFB)

Mill

7

Daily

Soil mulching, incinerated

Oil palm mesocarp fiber (OPMF)

Mill

7

Daily

Fuel for boiler

Oil palm shell (OPS)

Mill

4

Daily

Fuel for boiler

POME

Mil

60

Daily

Anaerobic treatment and discharged to the river

* 2010 data. Dry weight basis, except for POME.

 

It is estimated that the above figure will increase annually and by 2020, the total amount of solid and liquid biomass will reach 85-110 and 70-110 million tonnes, respectively (Agensi Inovasi Malaysia, 2012). Due to the abundance of the biomass, improper treatment of the biomass may create other issues. For example, most of the OPF, OPT and OPEFB are currently discarded at the plantation for nutrient recycling and mulching. However, too large amount of biomass discarded at the plantation will invite snakes and rodents. On the other hand, anaerobic treatment of POME using open pond system will generate methane which adds to the generation of greenhouse gas from the industry. Therefore, efficient treatment and utilization of the biomass are needed in order to ensure sustainable production of palm oil.

 Oil palm biomass consists of mainly carbohydrate in the form of cellulose and hemicellulose. On the other hand, liquid biomass from palm oil mill, i.e. POME contains substantial amount of oil and grease, COD, total solids and nitrogen (Mumtaz et al., 2010). Even though carbon compound in both solid and liquid biomass is in different form, but in overall the high carbon content of both solid and liquid biomass of oil palm indicate that the biomass are suitable to be used as feedstock for the production of value added products such as bioenergy, bio-based chemicals and biopolymers.

 

  1. Polyhydroxyalkanoates biopolymer from oil palm biomass

 Biopolymers refer to polymer materials derived from bio-based and renewable resources; such as bioplastics, biocomposites and lignocellulosic materials. Polyhydroxyalkanoates (PHA) is an interesting biopolymer as it is being produced by microorganisms intracellularly as carbon and energy reserve materials when they are under stress conditions (Anderson and Dawes, 1990). PHA can be generally classified into short-chain-length (scl) and medium-chain-length (mcl), depending on the number of carbons of the alkyl side chains. scl-PHA possessing alkyl side chains having up to two carbons, while mcl-PHA has at least three carbons on the side chains. Due to the difference in the total number of carbons, these PHAs have different requirement of substrate in fermentation. The scl-PHA requires simpler substrate such as sugars and volatile fatty acids (VFA).

There have been many reports on the production of PHA from oil palm biomass, both solid and liquid. Palm oil mill effluent (POME) for instance, is a good substrate for the production of PHA as it contains substantial amount of VFA. POME is generated as wastewater during sterilization of oil palm fresh fruit bunches (FFB), clarification of palm oil and effluent from hydrocyclone operations. With high biochemical oxygen demand (BOD) and chemical oxygen demand (COD), POME requires pre-treatment before being discharged into the environment. An anaerobic treatment method for POME which is coupled with the production of organic acids for subsequent use in PHA fermentation has been successfully developed (Hassan et al., 1996; 1997; 2002; 2006). It has been reported that the integration of POME treatment and PHA production will sufficiently provide a zero discharge system for palm oil mills.  Depending on the scale of operation, concentration of clarified organic acids obtained from treated POME varied from 50-100 g/L. The acids consisted a mixture of acetic, propionic and butyric acids (Hassan et al., 1996). The combination of these acids make POME suitable for the production of scl-PHA, especially poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV copolymer. PHBV is generally better in terms of mechanical and thermal properties compared to its homopolymer, poly(3-hydroxybutyrate), PHB.

Apart from the above studies, there have also been reports by other researchers on the production of PHA from POME. Salmiati and co-workers (2007) reported on the production of PHA from mixed microbial culture in POME. It was found that PHA accumulation in the bacteria reached 40% during the fermentation. Indeed, the use of POME as substrate for PHA production does not only contribute to the use of renewable carbon source for PHA production, but it also helps in the treatment of wastewater from palm oil mill. The 2-in-1 process helps to create sustainable production of PHA from oil palm biomass.

Recently, oil palm frond (OPF) juice has been introduced as another feedstock candidate for fermentation (Zahari et al., 2012a). OPF juice contains nearly 80 g/L of sugars, of which 70% is glucose. OPF juice is advantageous as fermentation feedstock due to its daily availability; on top of its easy processing, whereby only simple pressing is needed for obtaining the sugars. OPF juice has been utilized for the production of PHA (Zahari et al., 2012a and 2012b) and it was found that the use of OPF juice as substrate yielded higher PHA production compared to the commercial sugars having similar sugars concentration. The higher PHA production was contributed by other minerals and vitamins presence in the OPF juice, which enhanced the bacterial growth and PHA production.

Types and properties of PHAs produced from oil palm biomass are comparable to those produced from other feedstock. The summary of the PHA properties from various carbon sources is shown in Table 2.

 

Table 2. Properties of PHA produced from various carbon sources.

Type of PHA

Carbon source

Mw

(kDa)

Tm

Tensile strength (MPa)

Elongation to break (%)

Reference

PHB

Fructose

NA

177

43

5

Doi, 1990

Maple sap

507

177

NA

NA

Yezza et al., 2007

Mixture of commercial sugars (glucose, sucrose and fructose)

713

NA

NA

NA

Zahari et al., 2012a

Sodium acetate

523

153

31

22

Reddy et al., 2009

OPF juice

812

162.2

40

8

Zahari et al., 2012a,b

PHBV

Glucose

540

166

35

45

Reddy et al., 2009

Glycerol

610

171

37

69

Reddy et al., 2009

Glucose + propionic acid

990 - 1300

NA

NA

NA

Liu et al., 2009

NA

NA

145

20

50

Tsuge, 2002

POME organic acids

400 - 1000

139 - 156

NA

NA

Zakaria et al., 2010

 

PHB produced from OPF juice had higher molecular weight (MW) compared to other PHB produced from other substrates, and had similar mechanical properties compared to that produced from pure fructose. The properties of PHBV produced from POME organic acids on the other hand were varied according to the composition of 3HV fractions (Zakaria et al., 2010), however in overall high molecular weight of PHBV is achievable by using organic acids derived from POME. This shows that oil palm biomass can be a good fermentation substrate for the production of PHA. A detailed economic analysis to study the feasibility of PHA production from POME organic acids was reported by Hassan and co-workers (1997). It was concluded that coupling anaerobic treatment of POME with PHA production would reduce the price of PHA to less than 1 USD / kg, compared to the normal price at 6 USD / kg. The results from the study showed that the use of POME for PHA production is economically feasible, with additional advantage to the environment.

  

4.0 Conclusions and future perspectives

The present trend towards green and sustainable products with low carbon footprints will undoubtedly provide the push for the development of technologies related to the utilisation of biomass resources for value-added products. In conclusion, we can expect increased research and development efforts in the near future which will soon lead to more utilisation of oil palm biomass for sustainable and cost-effective biopolymers production. 

 

References 

Agensi Inovasi Malaysia. National Biomass Strategy: New wealth creation for Malaysia’s palm oil industry  (2011).

  1. Yacob, M.A. Hassan, Y. Shirai, M. Wakisaka, and S. Subash, Baseline study of methane emission from anaerobic ponds of palm oil mill effluent treatment, Sci. Total. Environ. 366 (2006), pp. 187-196.

 M.A. Hassan, Y. Shirai, N. Kusubayashi, M.I.A. Karim, K. Nakanishi, and K. Hashimoto, The production of polyhydroxyalkanoate from anaerobically treated palm oil mill effluent by Rhodobacter sphaeroides. J. Ferment. Bioeng. 83 (1997a), pp. 485-488.

A.J. Anderson, and E.A. Dawes, Occurrence, metabolism, metabolic role, and industrial uses of bacterial polyhydroxyalkanoates, Microbiol. Rev. 54 (1990), pp. 450-472.

M.A. Hassan, Y. Shirai, N. Kusubayashi, M.I. Abdul Karim, K. Nakanishi, and K. Hashimoto, Effect of organic acid profiles during anaerobic treatment of palm oil mill effluent on the production of polyhydroxyalkanoates by Rhodobacter sphaeroides, J. Ferment. Bioeng. 82 (1996), pp. 151-156.

M.A. Hassan, Y. Shirai, H. Umeki, H. Yamazumi, S. Jin, S. Yamamoto, M.I. Abdul Karim, K. Nakanishi, and K. Hashimoto, Acetic acid separation from anaerobically treated palm oil mill effluent by ion exchange resins for the production of polyhydroxyalkanoate by Alcaligenes eutrophus. Biosci. Biotechnol. Biochem. 61 (1997b), pp. 1465-1468.

M.A. Hassan, Y. Shirai, M. Inagaki, M.I. Abdul Karim, K. Nakanishi, and K. Hashimoto, Economic analysis on production of bacterial polyhydroxyalkanoates from palm oil mill effluent, J. Chem. Eng. Jpn. 30 (1997c), pp. 751-755.

M.A. Hassan, O. Nawata, Y. Shirai, N.A. Abdul Rahman, L.Y. Phang, A.B. Ariff, Abdul and M.I. Karim, A proposal for zero emission from palm oil industry incorporating the production of polyhydroxyalkanoates from palm oil mill effluent, J. Chem. Eng. Jpn. 35 (2002), pp. 9-14.

M.A. Hassan, A process for treatment of palm oil mill effluent and for conversion of the palm oil mill effluent into biodegradable plastics, Malaysian Patent. MY123658A. (2006).

  1. Mumtaz, N.A. Yahaya, A.A. Suraini, N.A. Abdul Rahman, L.Y. Phang, Y. Shirai, and M.A. Hassan, Turning waste to wealth-biodegradable plastics polyhydroxyalkanoates from palm oil mill effluent: Malaysian perspective. J. Clean. Prod. 18 (2010), pp. 1393-1402.

M.R. Zakaria, H. Ariffin, N.A. Mohd Johar, A.A. Suraini, H. Nishida, Y. Shirai, and M.A. Hassan, Biosynthesis and characterization of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer from wild-type Comamonas sp. EB172, Polym.

Z.U. Salmiati, Z. Ujang, M.R. Salim, M.F. Md Din, and M.A. Ahmad, Intracellular biopolymer productions using mixed microbial cultures from fermented POME, Water Sci. Technol. 56 (2007), pp. 179-185.

M.A.K.M. Zahari, M.R. Zakaria, H. Ariffin, M.N. Mokhtar, J. Salihon, Y. Shirai, and M.A. Hassan, Renewable sugars from oil palm frond juice as an alternative novel fermentation feedstock for value-added products, Biores. Technol. 110 (2012a), pp. 566-571.

M.A.K.M. Zahari, H. Ariffin, M.N.M. Mokhtar, J. Salihon, Y. Shirai, and M.A. Hassan, Factors affecting poly(3-hydroxybutyrate) production from oil palm frond juice by Cupriavidus necator (CCUG52238T), J. Biomed. Biotechnol.  (2012b), pp. 125865. 8 pages.

 

Tarikh Input: 30/11/2020 | Kemaskini: 30/11/2020 | nazlia

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