Alexander Szabo and Oscar Engle - Svenskt Vatten

treatment facilities simple, treatment ponds or Imhoff tanks were usually implemented. The idea
was that after one year of utilization, the responsibility for running and maintaining the treatment
facilities was transferred to the municipal authorities. However, not every local authority had the
resources to run the centralized treatment facilities and as a result centralized treatment systems
grew only from 3.5% in 1970 to 5% in 1990. This can be compared to septic tanks coverage in
urban areas which grew from 17.2% in 1970 to 37.3% in 1990 (Ujang & Henze, 2006).
In 1993 a new law, the Sewage Service Act, was implemented and a new Federal agency, the
Sewage Service Department was established. The main task of the new agency was to plan,
regulate and control sewage water treatment. Since 1993 the agency has been responsible for the
national privatization project and in 1993 Indah Water Konsortium (IWK) was given the task to
operate and maintain existing treatment facilities (Ujang & Henze, 2006). The reason for
privatizing was to assist the Sewage Service Department with maintenance of existing sewage
systems, refurbishment of old systems and constructions of new sewage systems in urban areas
(Ujang & Henze, 2006).
At the moment there are two standards for treated waste water quality, according to the
Environmental Quality Act from 1974. Every treatment system must comply with either standard
A or standard B. Standard A is used if the water is discharged upstream of any raw water intake
and Standard B is used when water is discharged downstream of a raw water intake (Sewerage
Services Department, 1998). The most important parameters of treated waste water to be
followed are Biochemical Oxygen Demand over a period of 5 days (BOD 5 ) and total suspended
solids (TSS). No discharge of treated waste water higher than the absolute values are permitted by
the law. Because of fluctuations in the quality of the treated waste water, the effluent waste water
quality should be designed to reach a lower “design” value (Table 1.1). This is to ensure that the
effluent waste water quality never reach above the absolute values. The permitted limits for
Standard A and Standard B can be seen in Table 1.1 below.
Table 1.1: Malaysian Design values for BOD 5 and TSS for treated effluent waste water quality. (redrawn
from Sewerage Services Department, 1998)
Parameter Standard A Standard B
Absolute Design Absolute Design
BOD 5 (mg/l)
TSS 2 (mg/l)
20 10
50 20
50 20
100 40
During the project the effluent standard from 1974 was changed. It came to our knowledge after
all the sampling from the pond was done that a new standard was introduced in December 2009.
The new standard is similar to the one of 1974. The permitted limits for BOD 5 and TSS levels are
unchanged. The main difference is the introduction of nitrogen and phosphorous removal
(Department of Environment, 2009). Because no measurements of nitrogen and phosphorous was
not done we will mostly use Standard A and Standard B from 1974 throughout the report. For
more information about the new effluent standard see Table C.1 in Appendix C.
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