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<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

Section 2
Environmentally Sound Technologies and Practices


1. Overview of the Sound Technologies and Practices section

Technologies which are environmentally sound are technologies which help protect the quality of the environment. It may be argued that technologies used to manage wastewater and stormwater are inherently environmental technologies, because without these technologies the pollutants in wastewater and stormwater will negatively affect the environment (Section 1). Some of these technologies may utilise less energy than others, produce less air pollution or hazardous sludge, or more suited to wastewater and sludge reuse. Hence some of these technologies are more sustainable. The application of a technology is dependent on local physical factors of land availability, its topography, climate, soil, availability of energy and existing land uses. Sound technology practice is therefore dependent on being able to fit the technology to the local conditions.

Sound practice is also dependent on the context of the local community where the technology is to be applied. Long term sustainability is a function of community resources (funds, skills) to afford the technology and its willingness to pay for the technology and its operation. Sound practices are therefore practices which fit into the environmental, economic, social, cultural and institutional setting of the community.

In this Section wastewater and stormwater characteristics are described to set the context for technologies that need to be used to manage the pollutants they contain. The description is also meant to indicate the resources that are contained in human excreta, and therefore its potential for reuse. Technologies for collection, treatment, reuse and disposal are then described, so that options for the different local environmental, economic and social contexts described above can be evaluated. The description is not meant to be exhaustive, but to enable the scientific basis of the technologies to be understood. The relationship between processes in engineered systems and natural purification processes is also presented, so that simple engineered systems that are more akin to natural systems can be appreciated. Sludge is produced from treatment systems, and a section is devoted to its characteristics, treatment, reuse and disposal. Finally sound technology practices are reviewed in the context of environmental, economic and social conditions of a community.


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