Water Quality Parameters: TURBIDITY

→) Occurs in most surface waters due to the presence of suspended clay, silt, finely divided organic and inorganic matters, plankton (algae) and micro-organisms. 

→) The suspended particles that cause turbidity range in size from colloidal dimensions (10 nm) to the diameters in the order of 0.1mm.

Sources:

→) Most turbidity in surface waters results from the erosion of colloidal material such as clay, silt, rock fragments, and metal oxides from the soil.

→) Vegetable fibers & micro organisms also contribute to turbidity.

→) Household and industrial wastewaters also contain turbidity-producing materials.

Impacts:

→)  When turbid water in a small, transparent container, such as a drinking glass, is help up to the light, an aesthetically displeasing opaqueness or “milky” coloration is apparent.

→) The colloidal material associated with turbidity provides adsorption sites for chemicals that may be harmful or cause undesirable tastes and odors and biological organisms that may be harmful.

→) Disinfection of turbid water is difficult because of the adsorptive characteristic of some colloids. 

→) In natural water bodies, turbidity may impart a brown or other color to water depending on the light absorbing of solids.

Measurement:

→) Turbidity is measure by determining the percentage of light absorbed or scattered. The name of the apparatus is Jackson Turbid meter.

→) Another standard method for measuring turbidity is the principles of nephelometry and measuring the light from particles.

→) Unit of turbidity is NTU (Nephlametric Turbidity Unit).

→) A turbidity in excess of 5 NTU is generally objectionable to consumers.