Physical-water-quality parameters

The physical-water-quality represented by human feeling and laboratory test

Human Feeling

• Sight
• Touch
• Taste or smell

Lab Test

1. Suspended solid
2. Turbidity
3. Color
4. Taste and odor
5. Temperature

One of physical-water-quality is suspended or/and dissolved solids form

The source of solids could be organic (as plant, fibers and biological solids) or organic particles (as clay, silt or other soil constituents) or immiscible liquids.

The measuring unit for (SS) is mg/litre or ppm (part per million) and used to measure the quality of waste water influent , the max allowed standard is 30 mg/l (ppm)


Turbidity

Turbidity is another physical-water-quality and of the extent to which light is either absorbed or scattered by suspended materials in water, turbidity is not a direct quantitative measurement of suspended solids.The source of turbidity as follow:

• For surface water results from erosion of colloidal material such as clay, silt, rock fragments, and metal oxides from the soil.
• From vegetable fibers and microorganism.
• Household and industrial waste water.
• Soaps, detergents and emulsifying agents produce stable colloids.

Turbidity measuring units is NTU (nephelometry Turbidity Unit) and FTU (Formazin Turbidity Unit).For drinking water max turbidity is

• 1 FTU ( EPA standard)
• 0.1 FTU ( AWWA standard)
• 0.3 NTU ( US Gov.)

Normally the pure water is colorless, it's also important physical-water-quality which the color due to suspended matters known as apparent color and the color due to dissolved solids is known as true color.The source of color came from the following:

• Contact with organic debris such as leaves, conifer needless, or wood.
• Iron oxides cause reddish water, and manganese oxides cause brown or blackish water.
• Industrial wastes from textile and dyeing operations, pulp and papers production, food processing, chemical production, mining, refining, and slaughterhouse operations.

Color-comparison tubes containing a series of standards may be used for direct comparison of water samples that have been filtered to remove apparent color.

The measurement units is true color unit (TCU), the instruments used known” Spectrophotometric” technique are usually in use.

In the field work, instrument employing colored glass disks that are calibrated to the color standard are often used.

The color measurement not used for waste water but for potable water and agriculture water.


Taste and odor

A wide variety of taste and odors may be attributed to water by consumers.

Substances that produce an odor in water will almost invariably impart a taste as well.

Sources of taste and odor usually from many substances with which water comes into contact in nature or during human use may impart perceptible taste and odor.

These include minerals, metals, and salts from the soil, end product from biological reactions, and constituents of waste water.Inorganic substances are more likely to produce tastes unaccompanied by odor .

Alkaline material imparts a bitter taste to water, while metallic salts may give a salty or bitter taste.

Organic material is likely to produce both taste and odor, biological decomposition of organic mayalso result in taste and odor, producing liquids and gases in water.

Also certain species of algae secrete an oily substance that may result in both taste and odor.

Taste and odor causing organic can be measured by using gas or liquid chromatography instrument.

Unit of odor ”threshold odor number (TON)”Max allowed for potable water TON of 3 (Public health service), it’s only as guide line, as EPA does not have maximum standard for TON.


Temperature

Temperature is not used to evaluate directly either potable or waste water.

The temperature of surface water governs to a large extent the biological species present and their rates of activity.

Temperature has not effect on most chemical reactions that occur in natural water system.

Temperature also has an assert effect on the solubility’s of gases in water.

Source of temperature in the natural water systems responds to many factors, the ambient temperature being the most universal, shallow bodies of water are more affected by ambient temperature then are deeper bodies.

The use of water for dissipation of waste heat in industry and subsequent discharge of the heated water may result in temperature changes in receiving streams.

Removal of forest canopies and irrigation return flows can also result in increased stream temperature.

Temperature measured by either of following:

Temperature also affects other physical properties of water, the viscosity of water increases with decreasing temperature, the maximum density of water occurs at 4 Deg. Cent., and density decreases on either side of that temperature (4 Deg.Cent.), a unique phenomenon among liquids.


from physical-water-quality to Water education


from physical-water-quality to Home page