**1. Introduction**

Palm oil industry is a significant industry sector and plays a significant role in Malaysia's economy as one of the largest palm oil producers in the entire world [1]. The palm oil industry in Malaysia contributes about 39% of the world palm oil production and also 44% of palm oil world export [2]. Due to this importance, a large area of land has been converted into oil palm plantation estate. At the same time more and more palm oil mill has been built to process the increasing amount of oil palm fresh fruit bunch (FFB) into crude palm oil [1]. The growth of the industry at the same time indicates the increase of wastewater or palm oil mill effluent (POME) produced and released into the watercourse, which will bring harm to the environment.

The process of extracting crude palm oil from the fresh fruit bunch consumes much water and therefore produces a large volume of wastewater. In Malaysia, a record of 0.67 cubic meters of POME generated in order to process one ton of FFB [1]. Approximately 5–7.5 tons of water is required to produce one ton of crude palm oil. Eventually, more than 50% of these water would become POME which is shown in **Figure 1** [2].

It is approximately 48–72 million tons, and 49–74 million tons of POME was generated in the year 2013 and 2014, respectively. In the year 2014, it estimated 19.66 million tons of crude palm oil produced with roughly 44 million cubic meters

**Figure 1.** *Palm oil mill effluent.*

of POME generated [3]. In POME generated by processing 1 ton of FFB, it contains about 29-30 kg of 30°C, 3-days Biochemical Oxygen Demand (BOD3) [1]. From the data of POME produced in the year 2014, if the raw POME discharged into the environment without any further treatment, the BOD discharged is equal to the waste generated by 75 million people which is the 2.5 times of current Malaysia's population [3]. POME is also said to be 100 times polluting than domestic sewage [1]. According to the Department of Environment (DOE) practice, there are two ways of discharging treated POME, which are into water course or land. For the discharge into the watercourse, there are seven contaminants contained in the POME regulated. The regulated parameters are BOD3, suspended solids (SS), oil and grease (O&G), ammoniacal nitrogen (AN), total nitrogen (TN), pH and temperature. For the discharge onto the land, the only parameter is BOD3 which set at 5000 mg/L. **Table 1** shows the characteristic of raw and treated POME obtained from the discharge point of the local palm oil mill in Malaysia and DOE discharge limit [2].

The most popular method to treat the POME in Malaysia is the ponding system due to low equipment cost and the system is easy to operate. In Malaysia, there are more than 85% of palm oil mills that are currently adopting this method to reduce the BOD of POME into an acceptable limit which is less than 100 mg/L in West Malaysia and 50 mg/L in East Malaysia. In the ponding system, the POME undergoes biological treatments which include anaerobic digestion process followed by aerobic ponding with the hydraulic retention time of 40 days or above. However, the ponding system also causes some drawbacks which are long hydraulic retention time (HRT), vast land needed and the release of greenhouse gases (methane). There are also many palm oil mills which are unable to achieve the discharge limit only by using the ponding system [3].

If untreated POME discharges into the watercourse, it will undergo biodegradation process and consume dissolved oxygen in the water which eventually


*Performance of Chitosan as Natural Coagulant in Oil Palm Mill Effluent Treatment DOI: http://dx.doi.org/10.5772/intechopen.94330*

#### **Table 1.**

*Characteristic of raw POME and DOE discharge limit [4].*

will kill the marine animals, especially fish in the river. The untreated POME, which is acidic, will cause the watercourse to turn acidic and affect the aquatic life. Moreover, the oil content in untreated POME tends to form a thick layer on the water surface that will prevent the absorption of oxygen. The dark brown color and unpleasant smell of POME will turn the stream into brownish and unacceptable for public consumption [2]. Apart from that, the high concentration of suspended solids will remain at the bottom of the river and undergo biodegradation, which will produce sludge oxygen demand (SOD) and deplete the dissolved oxygen [4]. In order to protect the environment, DOE Malaysia establishes a standard where the final discharge of treated POME that came out from the mill must be less than 100 mg/L of COD. Hence, for POME to have the minimum or no impact on the environment when discharging and to comply with the discharge limits, the palm oil mill must have an effective POME wastewater treatment system. The cost of maintenance and operation of the POME wastewater treatment system, availability of land and location of mill greatly influencing the choice and selection of POME wastewater treatment systems in Malaysia. In return, it will stress the industry players, especially small and medium scale palm oil mill financially. Therefore, the central idea of this study is to provide an inexpensive and uncomplicated method for small and medium scale palm oil industries to process POME before discharging to the watercourse. This study provides insights into utilizing chitosan and polyglutamic acid in the POME treatment process to remove pollutants that contribute to high COD, color, and TSS of POME.

## **2. Palm oil mill effluent**

#### **2.1 Source of POME in palm oil mill**

The most common way in extracting palm oil from fresh fruit bunches (FFB) is the wet palm oil milling process. Several stages of wet palm oil milling process required a tremendous amount of water and steam for washing and sterilizing. As a result, this generates a considerable quantity of wastewater or better known as POME from palm oil mill. **Figure 2** shows a simplified process flow diagram to produce palm oil.

In a palm oil mill operation using a conventional manufacturing process, there are three primary processing operations responsible for producing the

**Figure 2.** *Typical palm oil process flowchart [5].*

POME. These three primary processes are sterilization of FFB, clarification of the extracted crude palm oil and hydro-cyclone separation of the cracked mixture of kernel and shell. Sterilization process customarily carried out in horizontal cylindrical autoclaves known as sterilizers where the FFBs are cooked with steam at the pressure about 3 atm for 1 to 1.5 hours. The sterilization process aims to inactivate the natural enzymes in the fruits (lipases) and inhibit the splitting of fat into free fatty acid (FFA) and cause oil loss. Besides, the steam sterilization process loosens the fruits from the bunch and soften the mesocarp to ease the oil extraction. This station contributes approximately 36% of total POME [1]. The clarification process is to separate the oil produced from the press station, which is mixed with water and solid from the bunch fiber. The oil usually is separated from the mixture in the clarifier tank by using gravity, de-sander and also decanter. This station contributes the majority part of the POME, which is 60% [6]. The nuts from the nut silo will be cracked by nutcracker in the ripple mill. These cracked kernel and shell mixture are separated in air columns and by a water bath in hydrocyclone. This station only produces around 4% of POME. The POME generated from sterilizer condensate, clarification of oil and hydro-cyclone is in the ratio of 9:15:1 (36%:60%:4%). **Table 2** shows the characteristics of different source of wastewater in palm oil mill that combined to produce POME [1].
