16 ENVIRONMENT AND ENERGY
Wastewater and ecosystems
Wastewater, when improperly managed, can have detrimental effects on ecosystems.
Extracted from the United Nations World Water Development Report 2017
Wetlands have a series of natural filters along the water’ s flow path and can also replenish aquifers that can be as deep as a few kilometres.
There are numerous opportunities to create synergies between ecosystem services and wastewater management. These interactions can be examined from two perspectives. First, ecosystem services can contribute to wastewater treatment as an alternative or supplement to conventional water treatment systems. The water purification process provided by aquatic and terrestrial ecosystems can supply clean water suitable for drinking, industry, recreation, and wildlife habitat.
Second, the resources embedded in wastewater— including water, nutrients and organic carbon— can under appropriate circumstances be used for ecosystem rejuvenation and remediation, enhancing ecosystems services, with major benefits for economies and societies.
ROLE AND LIMITS OF ECOSYSTEMS IN WASTEWATER MANAGEMENT There is a clear link between sustainable wastewater management and healthy ecosystems, and if managed well, this relationship can be mutually beneficial. Green infrastructure( GI) refers to natural( e. g. riparian buffers, wetlands and mangroves) or semi-natural ecosystems( e. g. constructed wetlands, rain gardens, bio-retention ponds), which can provide services such as sediment filtration and pollution removal, comparable to certain functions of grey infrastructure( e. g. conventional piped drainage and water treatment systems).
The GI approach relies on the provision of ecosystem services to deliver primary water and wastewater management benefits, accompanied by a wide array of secondary co-benefits( e. g. carbon sequestration, biodiversity protection, recreation), in a cost effective and sustainable manner.
Rory Macnamara – Water, Sewage and Effluent
Protecting and restoring these GI systems benefits human society and contributes to healthy ecosystems. Riparian buffers are vegetated areas next to water resources that act as filters and protect water quality, provide bank stabilisation, and aquatic and wildlife habitat. Natural ecosystems are known as the kidneys of the environment, removing pollutants, regulating water flow and storing sediment. They can be very effective and economical in terms of providing wastewater treatment services, provided that these ecosystems are healthy, the pollutant load( and types of contaminants) in the effluent is regulated, and the pollution-carrying capacity of the ecosystem is not exceeded.
May 2018 Volume 24 I Number 3 www. plumbingafrica. co. za