Newsletter and Technical Publications
<Sourcebook
of Alternative Technologies for Freshwater Augumentation in Some
Countries in Asia>
5. RESULTS OF THE SURVEY
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.
|