Characteristics of Residual Oil Extracted From Palm Oil Mill Effluent (POME)

World Applied Sciences Journal 27 (11): 1482-1484, 2013
ISSN 1818-4952
© IDOSI Publications, 2013
DOI: 10.5829/idosi.wasj.2013.27.11.1422
Characteristics of Residual Oil Extracted from Palm Oil Mill Effluent (POME)
Sri Rizki Putri Primandari, Zahira Yaakob, Masita Mohammad and Abu Bakar Mohamad
Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment,
National University of Malaysia, Bangi 43600, Selangor, Malaysia
Abstract: Malaysia produces approximately 10 million tons of palm oil mill effluent (POME) annually.
This effluent is also called oily wastewater due to its oil and grease content of approximately 0.6-0.7%.
This study obtained a residual oil yield of 0.7%v of raw POME by extracting the residual oil from the palm oil
mill effluent via a solvent extraction process. The extracted residual oil has been analyzed to determine its
physical, chemical and fuel properties. The residual oil had the following characteristics: free fatty acid content,
7.756%; density, 0.907 g/cm3; viscosity, 43 cSt; acid value, 19.986; saponification value, 147.263 mg KOH/g oil;
unsaponifiable matter, 1.033%w; moisture content, 2.359%; carotene content, 407.895 ppm; and a similar fatty
acid composition to commercial palm oil. The similarity of the characteristics of the residual oil to those of
commercial oil and jatropha oil indicate the possibility of using the residual oil as feedstock in biodiesel
production.
Key words: Oily wastewater Residual oil Palm oil mill effluent Colloidal waste Biodiesel Environmental
INTRODUCTION Raw palm oil mill effluent (POME) is a colloidal

suspension, which isolates the oil from the effluent and
The palm oil industry is one of the most important cannot be separated based on density, unlike ordinary
industries in Malaysia. Increasing the palm oil industry oil-water mixtures. Several methods have been used to
capacity also increases its effluent output. The disposal remove the residual oil from POME, including adsorption
of effluent is therefore a serious problem that must be [2], chemical-biological methods [3] and solvent extraction
solved. Although no chemicals are used during the oil [4]. In this case, residual oil was extracted using solvent
extraction, the effluent still must satisfy threshold values extraction due to the ease of removing the solvent to
set by the Malaysian Department of Environment before obtain the oil for characterization. The objective of this
being disposed into a watercourse due to its oily and study is to characterize the properties of the residual oil
colloidal waste content, which requires special treatment from POME for biodiesel production. Several important
at high cost. The disposal of an oily effluent called palm characteristics of oil in biodiesel production were
oil mill effluent (POME) is one of the problems faced by quantified in this study, including the oil
the palm oil industry. The residual oil in the effluent is content, free fatty acid content, density, viscosity,
approximately 4,000-6,000 mg/l, while the regulatory acid value, saponification value, unsaponifiable matter,
threshold value for oil and grease is 50 mg/l [1]. moisture content, carotene content and fatty acid
Thus, the residual oil must be removed before being composition.
discharged into the watercourse to satisfy the threshold
value set by government. The presence of residual oil in MATERIALS AND METHODS
effluent causes several problems, such as an increase in
the chemical oxygen demand (COD) and biochemical Physical Properties
oxygen demand (BOD). It creates a film on the water Oil Extraction: Raw POME was collected from a local
surface and reduces the availability of oxygen for aquatic palm oil mill. Raw POME was transferred into a conical
organisms. This study aims to isolate this oil and measure flask and mixed with n-hexane as the solvent for the
its properties to add value to the residual oil. extraction process. The ratio of POME: solvent was 1:1.
Corresponding Author: Zahira Yaakob, Department of Chemical and Process Engineering,

Faculty of Engineering and Built Environment, National University of Malaysia,
Bangi 43600, Selangor, Malaysia. Tel: +60389216420.
1482
World Appl. Sci. J., 27 (11): 1482-1484, 2013
The mixture was stirred at 200 rpm for 20 min, after which Fatty Acid Composition: The fatty acid composition was
the mixture was transferred to a separator funnel. determined using an Agilent ÷6890 series gas
The mixture was allowed to stand until the solid POME chromatograph (GC) with a flame ionization detector (FID)
impurities settled. The upper layer of the extract was and a capillary column (30 x 0.25 x 0.25 mm). The FID was
filtered using filter paper and then placed in a rotary set at 240 °C with a flow rate of 0.8 ml/min. The injector
evaporator to recover the solvent. The raffinate was temperature was also set at 240 °C. Hydrogen was used as
re-extracted by the same procedure until the oil was the carrier gas. The peaks were identified by measuring
completely extracted. After recovering the solvent, the retention time of the samples and comparing them with
the residual oil was dried to remove the excess solvent at authentic standards analyzed under the same conditions.
110°C for 30 min. After the drying process, the oil was
placed in a desiccator to cool before further analysis. RESULTS AND DISCUSSIONS
The oil content in the effluent was determined by
weighing the extracted oil. Physical and Chemical Properties: Table 3 shows
the relative fatty acid composition of residual oil. In terms
Density and Viscosity: The density of the samples was of fatty acid composition, the biodiesel compound
determined at 20°C using an Anton-Paar DMA 4500 (fatty acid methyl ester) content of the residual oil is
density meter. The viscosity of the oil was determined similar to that of commercial palm oil.
using a Brookfield RV-I instrument assisted by an S03
spindle at 100 rpm. The test was conducted at room Biodiesel Production: A barrier in the production
temperature. of biodiesel from residual oil is its FFA content,
moisture content and SV. Although the residual oil has
Chemical Properties: Chemical properties are included some undesirable characteristics, it can still be processed
free fatty acid content (%ffa), saponification value (sv), into biodiesel. Much effort has gone into finding a way to
iodine value, moisture content, unsaponifiable matter and overcome this problem. One example is the addition of
carotene content were determined according to AOAC acid esterification prior to the alkaline transesterification
Official Method 993.20. process. Normally, the process of producing biodiesel
Table 1: Physical properties

Property Residual oil Commercial palm oil Jatropha oil
Oil content (%) 0.7 ± 0.34 - 48 ± 0.7
Density (g/cm3) 0.908 ± 0.06 0.922 ± 0.03 0.903 ± 0.09
Viscosity at room temp. (cSt) 43 39 46.95
Table 2: Chemical properties

Property Residual oil Commercial palm oil Jatropha oil
Free fatty acid, FFA (%) 7.756 ± 0.44 0.1 2.15 ± 0.02
Saponification value, mg KOH/g oil 147.263 ± 0.60 198.9 ± 0.12 192.5 ± 0.5
Iodine value 51 ± 0.31 45 ± 0.06 105 ± 0.27
Unsaponifiable matter, % w/w 1.033 ± 0.03 0.008 ± 0.05 0.85 ± 0.11
Moisture content, % 2.359 ± 0.32 - 1.15 ± 0.02
Carotene content (ppm) 407.895 ± 0.01 548 ± 0.04 100 ± 0.15
Table 3: Relative fatty acid composition (%) of residual oil

Fatty acid Residual oil Commercial palm oil Jatropha oil
Myristic (C14:0) 1.2 1.2 0.2
Palmitic (C16:0) 45.0 44.3 13.7
Stearic (C18:0) 3.7 4.6 7.1
Oleic (C18:1) 39.8 38.7 45.8
Linoleic (C18:2) 9.8 10.5 33.1
Linolenic (C18:3) 0.4 0.5 0.1
1483
World Appl. Sci. J., 27 (11): 1482-1484, 2013
from commercial palm oil begins with a filtering and 2. Kamal, A., M.O.J. Azzam and N.I. Abu-Lail, 2000.
degumming pretreatment process, followed by alkaline Olive mills effluent (OME) wastewater post-treatment
transesterification due to the <1% FFA content in the using activated clay. Sep Pur Tec., 20: 225-234.
feedstock. Using acid esterification, FFA can be reduced 3. Rivas, F.J., Beltran, O. Gimeno and P. Alvarez, 2001.
to less than 1% in feedstock containing over 1% FFA [10]. Chemical-biological treatment of table olive
Referring to [7], the residual oil was subjected to acid manufacturing wastewater. J. Env Eng., 127: 611-619.
esterification in the first stage to avoid soap formation. 4. Hameed, B.H., A.L. Ahmad and N.A. Hoon, 2003.
It was mixed with 1.43 %v/v H2SO4 and sufficient Removal of residual oil from palm oil mill effluent
methanol to produce a 0.28 v/v methanol to oil ratio. using solvent extraction method. J. Tekn., 38: 33-42.
The mixture was heated at 60 °C for 88 min. The second 5. Sudhir, C.V., N.Y. Sharma and P. Mohanan, 2007.
stage involved alkaline transesterification by mixing Potential of waste cooking oils as biodiesel feed
with 0.55 %w/v of KOH and sufficient methanol to stock. Emir J. Eng. Res., 12: 69-75.
produce a 0.20 v/v methanol to oil ratio at 60°C for 1.5 h. 6. Vyas, A.P., N. Subrahmanyam and P.A. Patel, 2009.
A 97% of yield of biodiesel could be achieved using this Production of biodiesel through transesterification of
procedure and the data have been tabulated in Table 4 Jatropha oil using KNO3/Al2O3 solid catalyst. Fuel,
along with data from the standard procedure. 88: 625-628.
7. Tiwari, A.K., A. Kumar and H. Raheman,
ACKNOWLEDGMENTS 2007. Biodiesel production from Jatropha oil
(Jatropha curcas) with high free fatty acids:
This project is financed by Universiti Kebangsaan an optimized process. Biomass and Bioenergy,
Malaysia under grant AP-2012-008. The authors would 31: 569-575.
like to thank the university administration for financial
support.
REFERENCES
1. Ahmad, A.L., S. Sumathi and B.H. Hameed, 2005.

Adsorption of residue oil from palm oil mill effluent
using powder and flake chitosan: Equilibrium and
kinetic studies. Water Research, 39: 2483-2494.
1484

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World Applied Sciences Journal 27 (11): 1482-1484, 2013

INTRODUCTION Raw palm oil mill effluent (POME) is a colloidal

Corresponding Author: Zahira Yaakob, Department of Chemical and Process Engineering,

Table 1: Physical properties

Table 2: Chemical properties

Table 3: Relative fatty acid composition (%) of residual oil

1. Ahmad, A.L., S. Sumathi and B.H. Hameed, 2005.

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