WaterThe

Crisis

ChemistM. Nazeih M. GamalAbu Qir Fertilizers Co.

Water

=

Life

WaterProperties

Physical Properties

- Colorless, odorless, and no taste.

- One ml weigh one g at 4oC.

- Its density increase by cooling.

- Molecular weight for water (H2O): 11.11% hydrogen

and 88.89 % oxygen.

Many of the unique properties of water stems from its ability to form hydrogen bonding.

Chemical Properties

Excellent solvent Transport of nutrients and waste products, making biological processes possible in an aqueous system.

Highest dielectric constant

High solubility of ionic substances and their ionization in solution.

Higher surface tension

Controlling factor in physiology; governs drop and surface phenomena.

Transparent to visible and longer wave length fraction of UV light

Colorless, allowing light required for photosynthesis to reach considerable depth in bodies of water.

Higher heat of evaporation.

Determines the transfer of heat and water molecules between the atmosphere and bodies of water.

Higher latent heat of fusion

Temperature stabilized at the freezing point of water.

Higher heat capacity

Stabilization of temperatures of organisms and geographical regions.

Water Sources

Natural Sources.

Industrial Sources.

Water Purposes

House, Industrial, Agriculture, and Others.

Water Distribution in the Earth

Ground water 30%

Lakes and Rivers 1%

others 1%

Two poles and Ice68%

0

20

40

60

80

100

Fresh Water3%

SalineWater 97%

Fresh and saline water

ditributionFresh water distribution

The HYDROLOGIC Cycle

International Law

International water Organizations

International water system

Waters that connected to each other in natural basin, even including any extension from this water inside two state country nations or more.

Involve the main waterway of river and its branches (sources and discharges).

International Law

International Water

Organizations

The four principles of International Law Assembly

Period No 48, 1958, New York

1. Each lakes and rivers system that have one discharged basin, considered

as one completely unit.

2. Except in cases of concords that lay downs between the given states.

3. Respecting of international law.

4. Respecting of another states that occupant on the same river basin.

Non Governmental Organizations

International Water Academy's

World Water Council

Water

Resources

Water

Used

Now and Future

Water Resources Assessment (WRA)

All works that's lead to the best understanding to type and quantity of water sources.

Water Used

Water quantity that need at given time and rate for given purpose like agriculture, drinking, navigation, or industry.

Comprehensive Water Resources Framework

It’s the framework for water resources, in which the water act as only one source with different uses and correlations with ecological, sociological and economical systems.

Water Yield

It’s the water volume that produced by given water system at point at definite time.

Water Balance

It’s the difference between the inside (feeding) and outside (used) water quantity from any water system at giving time.

Water Depletion

Used water < Feeding water

Water SystemFeeding Used Water

The study of Water resources and used is important to

determine the water balance

Steps of study

1. Determine the independent variable (population number) from year 1990, year 2000, then year 2025 depending on International Building and Development Bank data information.

2. Classification of water resources data information to conventional sources (surface and ground water) and non conventional (water treatment, desalination, and re-used), where the non susceptibility of water resources to be increase at limited level must be considered.

3. Analysis of water used according to its uses in domestic house, agriculture, and industry. There is direct functional correlation between the domestic house and population number.

4. The personal share from water resources determined according to its analyzing importance.

Water Resources and used

in EGYPT

YearPopulation

number

Water Resources

 Renewable%

Water Used

Personal

share m3/y

Water resources gap

ConventionalNon

conventional

TotalDrinki

ngIndus

tryIrrigatio

nTotalAB SurfaceGround

Desalination

Treatment

19905255.53.10.024.963.5923.14.649.757.412216.1+11.5+

20006275.57.40.059.174.05844.56.159.970.511943.55+12.05+

20258657.57.40.079.174.078489.8585.4103.2563729.20-11.95-

205112057.57.40.099.174.098410.6413.7111.92136.3161762.26-45.95-

Water Resources and Used in EGYPT

Now and Future

Billion cubic meter/year

Where

Water gap A = Resources - Used

Water gap B = Resources – Used (Depending on the personal

share is 1000 m3)

Facing of Water

Resources Gap

I- Consumption rationalization for available water resources.

II- Development of available water resources.

III- New water resources addition.

Consumption rationalization for available water resources

1. Maintenance and development of water transfer and distributed

networks.

2. Increase the efficiency of field irrigation.

3. Change of crop composition.

4. Development of irrigation systems.

Development of available water resources

1. Dams and reservoirs projects.

2. Decrease the water loss by evaporation from the surface of

reservoirs and water canals.

New water resources addition

Conventional Non

Conventional

Surface water

Ground water Water treatment

Desalination

Non Conventional New Water Resources

Addition

Non Conventional New Water Resources

Addition

(A) Water Treatment

1. Water Treatment and Water Use

The treatment of water may be classified into three major categories:

Purification for domestic use.

Treatment for specialized industrial applications.

Waste water treatment to make it acceptable for release or reused.

2. Municipal water treatment

Examples of water sources may be:

Polluted river with mud and swarming with bacteria.

Well water which may be too hard for domestic use and contains high levels of stain-producing dissolved iron and manganese.

Preliminary screening and comminuting

(grinding)

Grite removal in an aerated chamber

grit

Disinfection

Flash mixing

pH 10.5 – 11.5

5Ca2+ + OH- + 3PO43- Ca5OH(PO4)3 (s)

Lime Alum

Waste water in

Cl2

Major component of physical-chemical treatment of municipal water

Polymer, flocculants

Clarifier

(flocculation)

Recarbonation (lower pH)

CO2

Pressurized filters (10 PSI)

Activated

Carbon

filtersActivated Carbon

Spent Carbon

Receiving water

Schematic of a municipal water treatment plant

3. Treatment of water for industrial use

The kind and degree of treatment of water in this application depends on the end use:

Cooling water: Require minimal treatment.

Boiler feed water: Requires removal of corrosive substances and

scale forming solutes.

Food processing: Requires water free of pathogens and toxic substances.

The effective water treatment at

Minimum cost for industrial use is a

very important area of water treatment

Improper treatment of water for industrial use can cause problems, such as:

Corrosion.

Scale formation.

Reduced heat transfer in heat exchangers.

Reduced water flow.

Product contamination.

External treatment:

Is a basic treatment usually applied to plant’s entire supply, which use process such as aeration, filtration and clarification to remove solid material, hardness, and dissolved gases.

Internal treatment:

Is designed to modify the properties of water for specific applications:

Reaction of dissolved oxygen with hydrazine or sulfite

Addition of dispersants to inhibit scale

Addition of inhibitors to prevent corrosion.

Adjustment of pH.

Addition of chelating agents to react with dissolved Ca2+ and prevent formation of calcium deposits.

Disinfection for food uses or to prevent bacterial growth in cooling water (addition of biocide).

Addition of precipitants, such as phosphate used for calcium removal.

4. Sewage Treatment

Typical municipal sewage contains the following:

Oxygen demanding substances

Sediments

Grease and oils

Pathogenic bacteria and virus

salts

Algal nutrients

Pesticides

Refractory organic compounds

Heavy metals

Characteristics used to describe sewage (Raw water analysis):

Turbidity (NTU).

Suspended solids (ppm).

Total dissolved solids (TDS).

Acidity (pH).

Dissolved oxygen mg/l..

BOD mg oxygen/l.

Hardness as CaCO3 (ppm).

COD mg oxygen/l.

Primary treatment.

Secondary treatment (Biological treatment).

Tertiary treatment (Advanced treatment).

Typical municipal sewage treatment steps are:

Heavy metals removal

Organic Matter

O2

CO2 + H2O + Energy

N , P , Trace metals

New cells

40% C

60% C

Pathways for the removal of BOD in biological waste water treatment

Oxidation

Trickling filter or aeration tank for secondary waste treatment (Biological treatment)

5 .Industrial wastewater treatment

Wastewater to be treated must be characterized fully, particularly with a through analysis of possible waste constituents and their chemical and metabolic products.

)B (Water Desalination

How we can obtain fresh water from saline water by different methods depends on the water stability property.

Desalination process like any converter industry process,

i.e., the effective water desalination at Minimum cost.

Desalination Methods

Chemical Methods

Ion Exchange

Distillation / Evaporation Methods

MSF

Membrane Methods

RO

ED

Ion Exchange

Is the reversible transfer of ions between aquatic solution and solid material (Stationary phase) capable of bonding ions.

Strongly acidic cation exchanger

Reverse Osmosis (RO)

31% of total desalinate water produced by RO.

There are 4517 RO units from the total number 7536 of desalination units in the world, i.e., RO units represents 55% of the total number of desalination units in the world.

The spontaneous flow of water from a dilute solution to a concentrated solution, when the two solutions are separated by a semipermeable membrane.

Principles of Reverse Osmosis, RO

Osmosis:semi-permeable membrane

1 < 2

1 2

Osmotic Pressure:

P

P = (2 - 1) =

21

The pressure that must be applied to a concentrated solution to prevent osmosis.

Reverse Osmosis:

Reversing osmotic flow by applying a pressure in excess of osmotic pressure.

P

P > (2 - 1)

21

Multi – Stage Flash Evaporation (MSF)

* 56% of total desalinate water reproduced by MSF.

* There are 1036 MSF units from the total number 7536 of desalination units, i.e., MSF units represents 14% from the total number of desalination units in the world.

Fresh water is obtained by applying thermal energy to the seawater feed in multiple stages creating a distillate stream for fresh water uses, and a concentrate (brine) stream that is returned to the sea.

The MSF method depending on the fact that:

The MSF process is considered energy intensive, while RO is a lower energy process.

Electro - Dialysis (ED)

Electrodialysis is an electrochemical separation process in which ions are transferred through ion exchange membranes by means of a DC voltage.

(+) AnodeCathode (-)

(e-) Flow of electrons

Cl-

Na+

O2

H+

Cl2

H2

OH-

(+) Anode

Cathode (-)

Cl-Na+

C

A

A

C

C

Cl-Na+

Cl-Na+

Cl-Na+

Cl-Na+

Cl-Na+

(+) Anode

Cathode (-)

Cl-Na+

C

A

A

C

C

Cl-Na+

Cl-Na+

Cl-Na+

Cl-Na+

Cl-Na+

(e-)

DC

A = Anion membrane C = Cation membrane

Hybrid Desalination Methods

Hybrid desalination systems combining both thermal and membrane desalination processes with power generation systems are currently considered a good economic alternative to dual-purpose evaporation plants.

Hybrid (membrane/ thermal/power) configurations are characterized by flexibility in operation, less specific energy consumption, low construction cost, high plant availability and better power and water matching.

In recent years, the concept of simple hybrid multistage flash-reverse osmosis (MSF/RO) configuration has been applied to a number of existing or new commercial desalination plants.

Schematic diagram of commercially available simple hybrid desalination plants.

Schematic flow diagram of dihybrid NF/MSF desalination system.

Schematic flow diagram of trihybrid NF/RO/MSF desalination system.

Comparison between the total production of desalinate water and number of desalination units in Arabian countries and world :

ProcessNumber of unitsTot. production (m3/D)

WorldArabian countriesWorld%Arabian countries

MSF10365797,444,296566,186,967

RO415715574,113,015311,618,879

ED1032513677,6745314,733

Others12844011,063,4128192,925

Total7509305013,298,3971008,313,504

The different limits for facing of water gap

Environmental limit.

Technological limit.

Economical limit.

Sociological limit.

Political and licit limit.

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