MESOPHILIC AND THERMOPHILIC ANAEROBIC TANK TREATMENT
OF PALM OIL MILL WASTEWATERS
T. O. Peyton, Consultant
Flow General Incorporated
McLean, Virginia 22101
I. W. Cooper, Engineering Director
S. K. Quali. Environmental Engineer
Sime Darby Plantations Berhad
Kuala Lumpur, Malaysia
INTRODUCTION
In 1974 the country of Malaysia enacted the Environmental Quality Act which enabled
the Ministry of Science, Technology and the Environment to prevent, abate and control
pollution for the whole of Malaysia through regulation.
In 1977 the first regulation to become gazetted under this Act covered the discharge into
watercourses of effluent from the crude palm oil milling process. The watercourse discharge
parameters consist of limitations on biochemical oxygen demand, chemical oxygen demand,
total solids, suspended solids, ammoniacal nitrogen, total Kjeldahl nitrogen, pH and temperature. Compliance levels are staged over the course of four years; for example, on July 1,
1978, a BOD reduction to 5000 mg/1 was required, which is reduced annually to 2000, 1000
and 500 mg/1, the last effective on July 1, 1981. The critical parameter for control purposes
is BOD and fines are imposed based on the pounds of BOD discharged above and below the
limitation. This fine could approximate M$ 1000 per day ($400) for a typical mill without
treatment facilities. As   an alternative to watercourse discharge the regulations allow for
land application with pretreatment to a BOD of 5000 mg/1.
The conventional palm oil milling process involves steam sterilization of the palm oil
fruit, oil extraction by screw press and oil separations through hot water addition, decanta-
tion, centrifugation and purification. Four sources of effluent are produced. The two major
sources are from the fruit bunch sterilizers, where an oil-rich condensate is discharged, the
hot residual water and "sludge" from the centrifuge process. Two minor effluent streams
result from hydrocyclone shell separators and boiler blowdowns.
As indicated in Table I, the combined effluent stream is hot and highly concentrated in
organic solids with BOD3 at 30°C values ranging from 25,000 to 40,000 mg/1. TVS values
Table I. Parameter Levels for Watercourse Discharge, Land Application, Raw Effluent and Anaerobically
Treated Effluent
Parameter
J July 1981-30 June 1982
Watercourse Land
Discharge Application
Raw Effluent
Anaerobic
Discharge
BOD3, 30   (mg/1)
500
COD (mg/1)
1000
TS (mg/1)
1500
SS (mg/1)
400
NH4-N (mg/1)
10
TKN (mg/1)
50
fc»
5.0-9.0
45
5000
25,000-40,000
250-2000
45,000-75,000
3000-10,000
40,000-60,000
7000-14,000
20,000-30,000
2500-8000
40-150
650-1000
150-400
4.5-5.0
7.0-8.5
60-70
ambient
473