Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
The sanitation system in Indonesia has its own characteristics. Separating
black from grey water introduces high strength domestic wastewater flowing to
the treatment process. Consequently, this calls into question community
practices and perceptions with regard to domestic wastewater. Effluent
wastewater flows out of a primary treatment tank and goes directly to the
groundwater. Users do not realise what the consequences of that impacts are to
the community, and appear to believe that groundwater contamination is some kind
of natural process without any causal factors stemming from it. At the same time
knowledge concerning treatment technologies is absent.
The groundwater of the shallow wells is much affected by organics. NH4-N in
the dry season ranges between 0 and 10.7 mg/l and averages 9.0 mg/l. Fecal
coliform observed in the dry season ranges between 0 and 460,000 and averages
33,000 (MPN/ 100ml).
In Indonesia the septic tank usually treats only black water and therefore
volume intake of septic tanks in Indonesia is estimated to be much less.
The following data in Table 3.5 represent typical physical and chemical
parameter effluent concentrations from septic tanks:
Furthermore, bacteria, viruses, nitrates, metals and inorganic contaminants
can also be detected. Thus the strength of the pollutant load easily leads to
contamination of groundwater. Under Indonesian conditions, the effluent of
wastewater to a septic tank is much more concentrated than in Western conditions
and so it can be predicted that higher concentrations would be found percolating
into the groundwater. To overcome this situation, applied research is required
based on conditions specific to Indonesian in order to determine the options
available. In this case technical alternatives along with socio-cultural factors
seem to be the main considerations.
Table 3.5: Wastewater quality from septic tanks
|(Source: Ir. Caturono, Ir. Gunawan Wibisono,
Dip. ES. and Ir. Laksni Sedyowati Environmental Technology: Application in
Principle and Practice. Existing Domestic wastewater treatment processes.
Paper presented at Universitas Merdeka, Malang)
One district had envisaged installing 2000 latrines as increasing population
densities in the district reduced the number of open places for defecation; a
problem aggravated for women, who face restrictions in public places.
Demonstration pit latrines were provided, but the model sanitation schemes were
not adopted and were eventually abandoned. The failure of this aspect of the
project lay in the fact that the construction cost of US$ 200 per latrine was
far more than most people could afford. Also, the project did not succeed in
developing the necessary motivation, skills, and organisation within the
District Council to enable it to manage the project's software components.
Moreover, the Council was preoccupied with obtaining construction materials for
the water supply schemes.
Obviously then, with only four cities operating full scale systems, septic
tanks are still the most commonly used operation in Indonesia. However, as a
primary treatment system, its efficiency reaches 60% biological oxygen demand
(BOD) removal and recent research indicates that important consideration should
be given to this typical system because it only treats black water from the
toilet, while the grey water flows separately to open drains. Because of this,
BOD in the influent to the septic tank reaches up to 830 mg/L and is therefore
potentially a source of groundwater contamination, especially considering that
the tanks are rarely pumped out (Azwar, 1995). Because groundwater is the main
source of domestic potable water in the high-density areas of most cities in
Indonesia, it is imperative that groundwater contamination be avoided by
selecting appropriate sanitation options.
In the urban centres of more developed countries, such as Australia, Japan,
Singapore and Korea, a high degree of sanitation and treatment for public and
private flush toilets has been achieved.
The disposal of industrial wastewater to the public sewerage system is
controlled in the developed countries. Countries like Australia, Japan, Korea,
Hong Kong, and Taiwan do not allow industrial wastewater to be disposed in the
public sewerage system unless it complies with certain standards, which are
designed to protect the sewage treatment system.
In the developing countries of the Asia Pacific, most of the industrial activities
are generally located within residential and commercial areas. Their wastewater
is discharged into the public drainage system without pre-treatment or control.
This is unacceptable from both environmental and public health points of view,
as hazardous and toxic substances may cause much more serious and longer lasting
damage to the environment than domestic wastewater.