Extended Aeration

To complement the previous systems, mechanical surface aerators can be introduced at the aerobic ponds (Fig. 8). This effectively reduces the BOD through aerobic processes. The aerators are normally installed at the end of the ponding system before discharge. However, this happens only where land area is a constraint and does not permit extensive wastewater treatment. Otherwise, aerators must be provided to meet DOE regulations.

16.3 PALM OIL REFINERY EFFLUENT (PORE)

Following the production of CPO from the palm oil mill, the CPO is then subjected to further refining before it can be categorized as edible oil. Even after the clarification and purification processes, there are still large amounts of impurities such as gums, pigments, trace of metals, and soluble fats that cause unpleasant taste, odor, and color. There are three common types of operation in the palm oil refineries: (a) physical refining and dry fractionation, (b) physical refining and detergent fractionation, and (c) physical and chemical refining with dry/detergent fractionation [6].

Figure 6 Formation of islets of sludge in the middle of the pond. (Courtesy of Felda Palm Industries.)

16.3.1 Chemical Properties of PORE

The main sources of PORE are water from the deodorization process and cleaning operations within the mill (Fig. 3). The characteristics of PORE are very much dependent on the type of process employed. The main chemical properties of PORE are as described in Table 3.

Figure 7 A series of 3600 m3 open digesters for POME treatment. (Courtesy of Felda Palm Industries.)
Figure 8 An aerator system installed to accelerate BOD reduction at the aerobic pond. (Courtesy of Malaysian Palm Oil Board.)

In comparison with POME, PORE is less polluting. This is largely due to the absence of oil and grease, and its low organic load. From Table 3, it is obvious why most of the palm oil refineries in Malaysia have adopted physical refining and dry fractionation to produce edible oil. Not only does the system reduce the effluent problem, but higher yield and oil purity with lower operating costs are obtained.

Table 3 Chemical Properties of Palm Oil Refinery Effluent (PORE) Based on Different Operations

_Type of refinery processes_

Physical and chemical

Table 3 Chemical Properties of Palm Oil Refinery Effluent (PORE) Based on Different Operations

_Type of refinery processes_

Physical and chemical

Chemical

Physical refining

Physical refining and

refining with dry/ detergent

properties

and dry fractionation detergent fractionation

fractionation

Temperature

35

42

57

(°C)

pH

5.3

4.9

3.0

BOD (mg/L)

530

2640

4180

COD (mg/L)

890

5730

7700

Total solids

330

1170

2070

(mg/L)

Suspended

50

12

6

solids (mg/L)

Phosphorus

4

1

12

(mg/L)

Total fatty

220

1580

3550

matter (mg/L)

Source: Ref. 3.

Was this article helpful?

0 0
Waste Management And Control

Waste Management And Control

Get All The Support And Guidance You Need To Be A Success At Understanding Waste Management. This Book Is One Of The Most Valuable Resources In The World When It Comes To The Truth about Environment, Waste and Landfills.

Get My Free Ebook


Post a comment