Wastewater is a collateral damage of urbanization but can also become a resource.
Urban expansion and population growth inevitably lead to tensions in cities. This tension relates to resources, first of all to drinking water, and then to the consequences of the discharge of wastewater, which increases in proportion to the number of inhabitants and the water consumed. If this wastewater were treated, the needs of cities could be met while reducing the pressure on resources. Furthermore, a recycling policy should be encouraged as far as possible.
Most cities in so-called developing countries do not have wastewater management systems, due to absent, deficient or inadequate infrastructure. The rate of installation of new infrastructure is not keeping pace with needs, particularly in informal slum areas. Technical solutions exist, which vary according to the density of urban or rural areas or according to social and financial conditions. Public authorities must consider the problem of wastewater at the same time and with the same seriousness as access to drinking water at the risk of suffering irremediable pollution.
Wastewater is also a resource that is growing at the same rate as the population. It has long been considered a resource for agriculture.
Provided it is treated, wastewater can be a clean resource, available in quantity and without danger. It can then be used for the needs of agriculture on the outskirts of cities or as an alternative resource for the industrial sector in complete safety. In many places, water is far too precious to be used only once. Whindhoek, the Namibian capital, has a water recycling system that distributes drinking water from wastewater to about 30% of the population.
They are also a cheaper resource than desalinated or imported water, thus a source of savings for cities.
Treating wastewater and reusing it for new uses are the two components of tomorrow's sanitation.
* A global vision of the sanitation issue must be adopted, from the creation of the waste to its treatment to make it neutral for the natural environment or to make it a resource for new uses.
* To deal with the issue, all aspects must be considered for so-called developing countries: technical choice, financial cost, know-how and maintenance capacities over time, climate impact and social acceptability of the different uses.
* While sanitation is costly, its absence hinders the development and safety of cities and creates pollution that makes emerging and developing cities unliveable.