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