Sanitation sewage and treatment in big cities Two study cases:
Sanitation in big cities
Big cities with little sanitation infrastructure can easily be swamped by human waste. In Jakarta, with a population of nine million people, less than three per cent of the 1.3 million cubic meters (enough to fill more than 500 Olympic swim- ming pools) of sewage generated each day reaches a treat- ment plant – there is only the capacity to process 15 swimming pools’ worth. Compare this to a city like Sydney, with a popula- tion of four million, where 100 per cent of urban wastewater is treated to some degree. Sewage treatment plants process 1.2 million cubic metres per day (each person in Sydney produces nearly three times as much wastewater as a person in Jakarta).
In Jakarta there are more than one million septic tanks in the city, but these are poorly maintained and have contaminated the groundwater with faecal coliform bacteria. When tanks are emptied their contents are often illegally dumped untreated into waterways (Marshall, 2005). Jakarta has a network of ca- nals, originally built to control flooding but these have been partially filled with silt and garbage. This coupled with severe subsidence due to groundwater water extraction (60 per cent of residents are not connected to the water grid so rely on wells), results in increasingly severe flooding. Flooding and stagnant stormwater create conditions for mosquitoes and the incidence of dengue fever and other water related diseases such as diarrhoea and leptospirosis is increasing.
1.3 million cubic metres
1.2 million cubic metres
Daily generated sewage
Portion of sewage that reaches a treatment plant
Sources: this report. Figure 8: Case study to compare two urban centres. 1 million people