Agriculture Reference
In-Depth Information
12.10 Microbial Nanofiltration Technology for Exhaustive
Treatment of Drip Irrigation Water
12.10.1 Agricultural Wastewater Reuse Treatment
Technology
The lack of freshwater resources worldwide has become an indisputable fact. A
United Nations report has pointed out that 12 billion people across 80 nations face a
shortage in water resources. With the development of sewage purification techno-
logy, many countries are beginning to consider purification of sewage for supplying
drinking water to the public.
In 1962, Japan started recycling of sewage, and it has been with scale in 70 years.
With constant updating of sewage recycling technology, regeneration and costs
have continued to decrease, and the water quality has continued to improve. As a
result, sewage purification technology has gradually become an important measure
to alleviate the shortage of water resources. At the beginning of the 1990s, a
nationwide survey research was conducted in Japan, and a process design for
wastewater reuse was developed, which thoroughly investigated the feasibility,
operation, and application of wastewater reuse technology. Subsequently, this
technology was widely applied in the arid areas of Japan. As a result, in recent
years, water consumption in Japan has been decreasing, thus achieving initial
success in water conservation. Similarly, it has been reported that in the USA, the
city sewage recycling dosage is 2.6
10 6 m 3 /day and that 62 % of the reclaimed
water is used for agricultural irrigation. Furthermore, Israel has more than 200 sew-
age treatment projects with a capacity from 27 to 2
10 5 m 3 /day, and 100 % rural
sewage and 72 % city wastewater are being treated and reused, of which 75 % is
used for agricultural irrigation (20 % of total irrigation), and the rest is used for
groundwater recharge, industry and municipal constructions, and other purposes. In
Japan, during the mid-1980s, the amount of city sewage reached 6.3
10 7 m 3 /day,
and the regenerated water was used for water reuse system, farmland irrigation, and
river or city supplies. In addition, sewage reuse is also very common in Russia and
Western Europe.
The three levels of sewage treatment, which is composed of chemical coagu-
lation, sedimentation, filtration, and disinfection, have been shown to be effective in
achieving sterilization, removal of particles, turbidity reduction, increased cleanli-
ness of recycled water, and esthetic sense. Furthermore, exhaustive treatment
technologies such as activated carbon adsorption, oxidation, ultrafiltration (UF),
and reverse osmosis (RO) can produce water with a better quality than the tradi-
tional drinking water. Currently, in California, USA, there are more than 50 level
3 sewage treatment facilities with the most strict water quality control criteria (e.g.,
0 % pathogens in the recycled water).
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