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2.1.2 Palm oil mill effluent

There are several unit operations of milling of oil palm included sterilization, stripping or
threshing, digestion, and extraction as shown in Fig. 2.2. Huge volumes and quantities of
wastewater and solid wastes were produced in the palm oil mill industry. Generally, palm oil
mill effluents (POME) were generated mainly from extraction, washing, and cleaning processes.
The production of 1 tonnes crude palm oil is required approximately 5.0-7.5 tonnes of water and
finally more than 50% of the water ends up as POME (Rupani et al., 2010). Every tonne of fresh
fruit brunch, POME will be discharged from the mill approximately 0.50-0.75 tonnes, at the
same time; large quantities of solids wastes is also generated such as 23% of empty fruit bunch
(EFB), 12% of mesocarp fiber, and 5% of shell (Najafpour et al., 2005; Rupani et al., 2010).
Raw palm oil mill effluent (POME) is a viscous acidic brownish fluid consisting of carbohydrate
content ranged 8.3 – 24.7 g/L which is indicated that it could be used as a good potential
substrate for generates hydrogen through dark fermentation process. Moreover, POME is also
contains a relatively high lipid content which is indicated that it is an organic materials suitable
and good substrate for generates methane through anaerobic dark fermentation process. Physical
and chemical characteristics of POME obtained from several literature reviews are summarized
in Table 2.2. There are several studies have been successfully of the hydrogen and methane
production from POME as shown in Table 2.3.

Table 2.2 Physical and chemical characteristics of palm oil mill effluent (Yossan et al., 2012;

Mamimin et al., 2012; O-Thong et al., 2008; Badiei et al., 2011; Fang et al., 2011;

Zinatizadeh et al., 2007).

Parameters Unit Concentrations
pH - 4.2 – 4.5
Chemical oxygen demand; COD g/L 45.0 – 100.0
Total nitrogen g/L 0.8 – 1.5
Total carbohydrate g/L 8.3 – 24.7
Total phosphorus mg/L 0.5 – 1.3
Oil g/L 2.3 – 10.6
Total solid; TS g/L 17.0 – 72.0
Total volatile solid; VS g/L 13.2 – 48.6
Alkalinity mg/L as CaCO 3 50.0 – 200.0
Total volatile fatty acid; VFA g/L 0.8 – 3.3