24
ENVIRONMENT AND ENERGY
Municipal and urban wastewater( Part 1)
In this edition, Plumbing Africa discusses the sources and impacts of municipal and urban wastewater, highlighting the prospects for wastewater production and looking at the opportunities for water reuse and recycling.
Extracted from United Nations World Development Report
Figure 1: Percentage of population served by different types of sanitation systems.
Municipal wastewater originates from domestic, industrial, commercial and institutional sources within a given human settlement or community. Urban wastewater includes both municipal wastewater and urban runoff. Since municipal and urban wastewater production is heavily dependent on the form and function of urban systems, the current and future patterns of urbanization must be critically examined in order to develop more sustainable approaches to wastewater management in the coming decades.
Figure 1 shows a breakdown of sanitation coverage by region, and hence of formal wastewater collection. It is clearly evident that sewers for wastewater collection are the favoured choice for much of the developed world, in spite of the use of on-site services in many rural areas and in areas undergoing unplanned urbanisation.
URBANISATION AND ITS IMPACT ON WASTEWATER PRODUCTION Urban areas around the world are facing enormous challenges. The acceleration of urban growth, changes in family and work practices, and the expansion of informal settlements will increasingly challenge the provision of services.
This is compounded by the impact of extreme events, climate change and migration in areas in conflict. Changing patterns of urbanisation have resulted in more inequity, with the poor in some developed regions facing the same challenges as those from developing regions.
By 2030, global demand for energy and water is expected to grow by 40 % and 50 %, respectively( UN- Habitat, 2016). Most of this growth will be in cities, which will require new approaches to wastewater management.
At the same time, wastewater management may also provide some of the answers to other challenges, including food production and industrial development.
URBAN FORMS The definition of rural and urban is most commonly based on national technical definitions related to geographical boundary considerations rather than population density or other defining characteristics.
However, in order to understand municipal wastewater production, it is necessary to consider a further analysis of‘ urban’, as differing urban forms do not only produce wastewater in different ways, but also guide the potential choices for the collection, treatment and use of wastewater( see Table 1).
September 2018 Volume 24 I Number 7 www. plumbingafrica. co. za