沙漠研究 19-1, 291- 294 (2009 )Journal of Arid Land Studies“Desert Technology IX ”
Refereed Paper

A Proposal of a New Supply System of Fresh Water for Afforestationof the Desert in the Middle East
N. SAHO1, S. YOSHIZAKI2, A. MOCHIZUKI3
Abstract: Many countries that import energy resources, such as crude oil and liquefied naturalgas, from the Middle East have a lot of domestic wastewater, most of which is discharged intorivers and the ocean after being purified by a high-class treatment. Meanwhile many Middle
Eastern oil-producing countries that export energy resources have vast deserts and a large
demand for the fresh water needed for irrigation. Meanwhile, large crude oil carriers andLNG tankers that are used to transport energy resources need to load and discharge a large
amount of ballast water to safely voyage across the ocean. However, that ballast waterpollutes oceans on a global scale by diffusing foreign aquatic microbes. This paper suggest a
new system in which large tankers load highly purified recycled water as ballast water, voyage
to Middle East, and discharge it for use in irrigating the desert there. Thus the system will
provide a solution to some of the environmental issues that these oceanic ships cause andcontribute to preserving the global environment.
Keywords: Afforestation, Ballast water, Fresh water

1. Introduction
In the oil producing country of the United Arab Emirates (UAE), desert is being afforested in order toimprove the living environment and protect farmland from sand and wind (Allison, 1964; Yoshizaki, 1992).
The afforested area has been expanding since 1970 and reached 200,000 hectares in total in 1991 (Al-Asam,1992). Due to most of the irrigation for afforestation relies on groundwater, the groundwater level has
lowered and salinization is in progress because of excess pumping to catch up with the expansion of theplantation. In order to maintain afforest, a new water source must be secured in the near future.
Meanwhile, a wary eye has turned to the ballast water drained from ocean ships that causes serious
oceanic pollution because of worldwide diffusion of foreign organisms (Fukuyo, 2000). In February 2004,
the International Maritime Organization (IMO) adopted the international treaty on ballast water(International Conference on Ballast Water Management for Ships, 2004). Once this treaty goes into
effect in 2009, the amount of residual microorganisms in the ballast water from ships will be strictlyregulated.
Many countries importing crude
oil from the Middle East have theOil-producing country
Ship
Oil-importing countryin Middle East
water resource which is not exploited
Sewage,effectively. Most of the produced
rain water
Crude oilwater by a high-class treatment
Crudeoiltank(hereafter "recycled water") fromdomestic wastewater is discharged
Crude oil tankinto rivers, lakes, or the ocean. This
recycled water contains a large
Crude oil tanker
Recycling
Recycled
amount of nitrogen and phosphorus
plantwater
which becomes a cause ofeutrophication and it is one of theAfforestation inreasons which are not reused.
Recycled water
Recycled water desert.
Ballast water tank
tankThis paper proposes a watertankcycle system that contributes toFig. 1. Flow of new circulation system with recycled water.
preserving the global environment by
1

Mechanical Engineering Research Laboratory, Hitachi, Ltd. Ibaraki, Japan
Faculty of Environmental and Information Studies, Musashi Institute of Technology, Japan
3
Research and Development Group, Hitachi Plant Technologies, Ltd. Tokyo, Japan2292

Table 1. Comparison of quality of recycled water and river/lake water in Japan.
CODT-N
T-PColi.
Type ofSSBOD(O2mg/L)(mg/L)(mg/L)(MPN/mL)
water(mg/L)(O2mg/L)
Recycled

2

3.6

7.3

6.9

0.5

2River

10.0

1.4

3.1

2.6

0.10

31

Lake25

4.0

8.2

1.9

0.15

74

SS: suspended solid, cfu: colony forming unit, BOD: biological oxygen demand, T-N: total nitrogen, COD: chemical
oxygen demand, T-P: total phosphorus, Coli.: Coliform

providing a solution to the problems of two different regions linked by maritime trade. In this system, as
seen in Figure 1, a tanker has separate tanks for ballast water and oil. In an oil importing country, the oil
is unloaded, and then recycled water is loaded from storage tanks near the port of call.
The tanker returns to an oil producing country in the Middle East and unloads the recycled water
before loading crude oil. The unloaded recycled water is stored in tanks near the port for use in irrigation.
The tanker is filled with crude oil and voyages to an oil importing country.
This water cycle system offers many benefits: (1) Pollution of the ocean’s biological environment isprevented by removing ballast seawater that contains various microorganisms inhabiting the seas of oil
importing countries. (2) Ballast seawater will not need to be purified before dumping, which as a result
reduces the cost of such water purification operations. (3)Using fresh water for ballast decreases
corrosion on ballast tank walls and lessens the inclusion of sludge that may be pumped up together withseawater in a shallow sea. Additionally, this reduces maintenance costs of the tanks (such as periodical
painting and cleaning deposits on the ship's bottom).
Table 1 lists the qualities of recycled water, river water, and lake water in Japan. The quality ofrecycled water (Northern Purification Center, 2004) was measured at the recycling plant near the port ofcall, and the listed values are yearly averages for 2003. The water quality value of the river isTonegawa’s annual average water quality (River Bureau, 2005). The water quality value of the lakes is
Kasumigaura’s annual average water quality (River Bureau, 2005). The quality of river and lake waterrunning through urbanized areas is comparatively eutrophicated. The items that differ considerably inquality between recycled water and river/lake water are the values of total nitrogen (T-N), total phosphorus(T-P), and coliform bacillus. The T-N and T-P values are high in recycled water— specifically theconcentration of T-P is three to five times higher than that of river/lake water. It is known that nitrogen andphosphorus are essential to grow plants, so their comparatively high concentration in the recycled water
will not negatively affect the afforestation. Since recycled water is sterilized during treatment, it contains
far less coliform bacillus compared with river/lake water. The values of BOD and COD of recycled water
are nearly the same as river/lake water.
2. Methods
2.1. Standard form of afforestation in desert region.
The standard form of afforestation in the desert region in UAE (Yokota et al., 1997) is shown inFigure 2. To protect the afforested area from feeding damage by camels, sheep, etc., it is surrounded by afence of two meters or higher, inside of which trees are densely planted to form a belt for protection.
Inside the belt, the main afforestation trees are planted at intervals of seven meters with an average densityof 200 trees per hectare. As for standard irrigation, in the first year, 31.82×10-3 m3 (seven gallons) ofwater are given to each tree a day, in the second year, 22.73×10-3 m3 (10 gallons) of water are given to eachtree every other day, and in the third and later years, 30.31×10-3 m3 (20 gallons) of water are given every
three days. The amount of irrigation water each time is averaged, but the frequency is adjusted by taking
into consideration the water leaching below salty soil layers underground. For irrigation, water isdripped.

293

Fence

Protect ed tree

3.5 m
Main tree

3.5 m

7m
7m

Fig. 2.

Standard form of afforestation in desert regions in UAE and photograph of afforested area.
Recycled water from urban households used for some of the water for irrigating these woods.

In the UAE, 85% of groundwater is used for agriculture and afforestation, and the remaining 15% isused for drinking water (Al-Afifi, 1993). Since the water necessary for irrigation is taken fromunderground, lowering water levels and salinizing the underground water are becoming serious issues.
One way to secure water for afforestation is to use the recycle water. Mixing the treated water and theunderground water is being attempted in order to dilute the salinized water for use in afforestation in UAE.
2.2. The amount of ballast water to the Middle East.
The amount of oil
Table 2. Amount of oil exported from Middle Eastern countries. Estimatedexported from the UAE andamount of transportable recycled water and estimated tree plant area.
the all of the Middle East
Crude oil export volume data from 2002. Amount of recycled water(JapanPetroleum
assumed to be 35% of crude oil export weight and 0.8 of crude oil density.
Development Associationand Japan National Oil
Exported
Estimated afforestation
Recycled water
Corporation, 2003), theItem
crude oilarea
6 3(10 m /year)(106m3/year)(ha)estimatedamountofrecycled water which canJapan and UAE
58.1
16.27
7,352
be carried for irrigation byJapanand Middle
oceanic
ships,
and216.3760.58
27,381Eastestimated plantable area
World and Middle
which can be maintained
1140.63309.38
144,342Eastby the imported recycledwater are shown in Table 2.
The potential amount of recycled water that can be carried from Japan to the UAE and the all of the Middle
East is about 16,270,000 m3 and 60,580,000 m3 per year, respectively. Including all areas of the world,
the figure becomes 309,380,000 m3 per year.
3. Results and Discussion
3.1. Estimated afforestation area in a desert.
Estimated irrigating areas shown in Table 2, which can be maintained by the imported recycled waterof 16,270,000 m3, 60,580,000 m3 and 309,380,000 m3 per year, are a vast 7,352, 27,381 and 144,342
hectares, respectively. If salinized underground water is used for afforestation after being mixed withrecycled water, the maintainable area will be further expanded. As a base of comparison, the annual
amount of discharge recycled water from Northern Purification Center was 25,550,000 m3. At the sametime, the use of recycled water partly solves the problems of the lowering underground water levels and294

salt-coagulated soil.
From the viewpoint of global warming, afforesting deserts is currently attracting attention because it
contributes to reducing the green house effect gas by sequestrating carbon dioxide from the atmosphere.
In Middle Eastern countries, when oil is exported by tankers, recycled water can be imported on theirreturn trips. In this water cycle system, water for irrigation is thus steadily secured for the long term.
3.2 Environmental preservation effect.
At the same time, oil importing countries benefit from exporting recycled water as ballast water
because nitrogen and phosphorus that cause eutrophication at home can be transported and used abroad.
Assuming the concentrations of nitrogen and phosphorus in recycled water are 6.9 mg/L and 0.5mg/L (thevalues in Table 1) respectively, the annual amount of nitrogen exported from Japan to UAE and the all ofthe Middle East will be 112 and 418 tons, and that of phosphorus will be 8 and 30 tons, respectively. The
annual amount of nitrogen and phosphorus transported from the rest of the world to these countries will be2,204 and 160 tons respectively, and all of these compounds will be consumed as nutrients for afforestation.
From these data, it is clear that supplying such nitrogen and phosphorus to afforested areas preventseutrophication in the water environments in oil importing countries as well as been helpful in maintaining
the soundness of the recycled water-released environment.
4. Conclusions
The water cycle system (Saho et al., 2005) in this report can prevent the contamination of the ocean’s
biological environment, which is caused by ballast water discharged from tankers offshore oil producing
countries. Recycled water used for the ballast water in tankers on return trips has the potential to irrigate
146,320 hectares of desert for afforestation in the Middle East. Oil importing countries will benefit byfinding an environmentally safe use for the recycled water produced at their wastewater treatment facilities.
This system can be applied not only to oil tankers but also LNG tankers, ore or coal carriers, and bulkers.
References
Al-Afifi M.A.R. (1993): UAE’s agriculture offers business and food security, Agriculture and Equipment International, 44: 122-123.
Allison L.E. (1964): Salinity in relation to irrigation. Advance in Agronomy, 16: 139-180.
Yoshizaki S. (1992): Desert Revegetation in the United Arab Emirates. Japan Greenery Research and Development Center, 19: 15-20.
Al-Asam M.S. (1992): Country report for the United Arab Emirates, Symposium on the Greening of the G.C.C. Countries,
Proccedings: 135-166,
Fukuyo Y. (2000): Increases of Frequency and Geographical Distribution of Harmful Plankton and Possible Responsible Mechanisms
for the Increase. NAVIGATION, 145: 13-18,
International Conference on Ballast Water Management for Ships (2004): International Convention for the Control and Managementof Ships’ Ballast Water and Sediments. IMO, BWM/CONF/36: 22
Japan Petroleum Development Association and Japan National Oil Corporation (2003): Oil Resource Development Data 2003, 8-92.
Northern purification center (2004): Outline of the Northern Purification Center -Wastewater Treatment Plant- 2003. Mie Prefecture
Sewage Works Public Corporation.
River Bureau (2005): Water quality of TONEGAWA in 2003, Japanese River Water Quality Yearbook 2003. Ministry of Land,
Infrastructure and Transport:288.
River Bureau (2005): Water quality of KASUMIDAURA in 2003: Japanese River Water Quality Yearbook 2003. Ministry of Land
Infrastructure and Transport: 574.
Saho N., Isogami H., Mizumori T., Mochizuki A., Imamura Y. (2005): Freshwater Supply System, IRAN Patent, Registration Number
P31139.
Yokota H., Abe M., Shoji T., Kiriiwa Y., Ozawa K., Yoshizaki S., Oishi A. (1997): Effect of irrigation water salinity on the growth oftrees for revegetation in the United Arab Emirates. Proceeding of International Plant Nutrition Colloquium, 415-416.