Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
3.1 Wastewater characteristics (Topic a)
3.1.1 Water supply and sanitation
Across the region, the most significant progress in water supply and sanitation
was made in East Asia (People's Republic of China, DPR Korea, Hong Kong, Japan
and Republic of Korea). With the exception of the People's Republic of China,
the East Asian countries achieved 100 per cent coverage of safe drinking water
supply and sanitation in 1990. The People's Republic of China achieved safe
water supplies for 87 per cent of its urban population. Other sub-regions have
also made great improvements in urban water supply since 1980, particularly
in South Asia. However, progress in sanitation has lagged behind, most notably
in urban India and Bangladesh. Whilst urban areas throughout the region are
now better served with water, sanitation and health services, the urban poor
in slums and squatter settlements have generally been overlooked for the reasons
mentioned earlier (ESCAP 1993).
The volume of wastewater depends upon water supply coverage and industrial
demand. The water supply demand for developed countries is about 250-300
L/person/day, with all of the population having access to water supply service.
In the developing countries the water supply demand is about 160-200
L/person/day, with only 60% of the total population having access to an adequate
water supply. In urban areas the proportion increases to 90% of the population.
Taking the case of Indonesia, the volume of wastewater introduced to a septic
tank system is approximately 160 L/person/day. Typical sources of household
wastewater, expressed on a percentage basis are toilet (30 %), laundry (15 %),
bath (25%), kitchen (10%) and other (7%) (Caturono et al., 1996).
A survey conducted in Vietnam showed that sewage flows have been calculated
on the basis of an average flow of 150 L/person/day, for the year 2015, compared
to the long-term water supply demand, which was estimated as 180 L/person/day.
Table 3.2 shows the estimated domestic public water supply and wastewater flows
for the different types of cities in Vietnam. Wastewater flows are very uncertain
as the flows are not measured in any of the cities. It can be seen that the
estimated wastewater flows for the Class I cities (very big cities with population
> 3 million) are higher than domestic water supply. This may be explained
by the fact that many households are using private water wells and some of these
households might also be connected to public sewers. This is particularly common
in the South, for example in Ho Chi Minh City (HCMC). The data reveal that water
supply is increasing with the city size and that this trend is even stronger
with regards to wastewater. Specific wastewater flow is only 39 L/person/day
in the Class III cities ( big medium cities with population < 1 million),
while Class II cities (big cities with population between 1 million - 3 million)
flow is 69 L/person/day increasing to 125 L/person/day in Class I cities. This
reflects the fact that a smaller proportion of households with flush or pour
flush toilets are connected to public sewers or drains in the smaller cities.
Table 3.2: Public water supply and wastewater flows in Vietnam
|City Class I
|City Class II
|City Class III
With the rapid development of the economy and continued urbanization growth,
the amount of water used for industrial and municipal purpose has been
increasing. Total water consumption in China in the late 1960ís was about
476.7 billion cubic meters, of which 57.2 billion cubic meters of water (about
12% of the total amount) were consumed in urban areas and by industries. The
quantity of water used for industrial and municipal purposes in 1993 was about
114.3 billion cubic meters (about 22% of the total amount). Industrial and
municipal water consumption in China increased by 100% over 15 years (Lin 1999).
Water supply needs in Central Asia in particular are still poorly served. The
progress in sanitation is less impressive, particularly in South Asia where less
than 5 % of the rural population in Bangladesh, Bhutan, India, and Nepal had
access to adequate sanitation by 1994.
Wastewater from industries depends on the type of industry and degree of
industrialisation, which varies from country to country. Volume of wastewater
produced per industrial establishment in the Asia Pacific countries is generally
less than in Europe.