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<Sourcebook of Alternative Technologies for Freshwater Augumentation
in Some Countries in Asia>


The results of the survey are presented below in Table 2 in summary form and in greater detail in Parts B and C. Technologies have been considered in four focal areas; water conservation , wastewater treatment and reuse, freshwater augmentation, and upgrading the water quality of natural waters.

Water conservation technologies include: water recycling in industries (i.e., cleaning wastewater for reuse in the same or other processes), dual distribution systems with drinking water in one system and water of marginal quality for non-potable uses in another, and mono-molecular organic surface films on the surfaces of water storage reservoirs to reduce evaporative losses.

TABLE 2. Summary Evaluation of Alternative Technologies for Freshwater Augmentation in Asia.

Wastewater treatment and reuse technologies include: reuse of irrigation water by tapping return flows from the drainage system for further irrigation use downstream, the use of sewage effluent in aqua-culture (primarily the use of night soil and fecal-contaminated surface waters for fertilizing fish ponds, and irrigation), primary wastewater treatment (in which organic and inorganic materials are removed from waste water through sedimentation and filtering), secondary wastewater treatment (in which also the non-settleable solids are removed, primarily through biochemical processes, to promote the degradation of organic pollutants), advanced wastewater treatment such as carbon adsorption, microstraining, and desalination, and water treatment by lagoons and wetlands (as a form of secondary wastewater treatment utilizing the naturally occurring processes in these areas).

Freshwater augmentation technologies include: rainwater harvesting from roofs into jars and pots or small dams, fog and dew harvesting to condense air-borne moisture into liquid water for drinking water supplies or irrigation, small-scale water storage facilities including small ponds, tanks, surface reservoirs, and underground reservoirs formed by subsurface obstructions or dams, artificial groundwater recharge using infiltration from the surface or injection via deep wells, and cloud seeding.

Technologies for the upgrading of the quality of natural waters through desalinization include distillation, reverse osmosis and electrolyte systems.


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