VPE 511: Environment and Environmental Hygiene (2+1)

EXERCISE-4: ESTIMATION OF TURBIDITY

Procedure

• 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 and microorganism may also contribute to turbidity. Household and industrial waste waters may contain a wide variety of turbidity producing materials. Soaps, detergents and emulsifying agents produce stable colloids that result in turbidity. Although turbidity is not measured on waste water discharged of waste waters may increase the turbidity of natural bodies of water.

Impacts

• Turbid water has aesthetically displeasing opaqueness and ‘milky’ colouration. The colloidal materials associated with turbidity provides adsorption site for chemicals that may be harmful or cause undesirable taste and odours and for biological organism that may be harmful. Disinfection of turbid waters is difficult because of the absorptive property of some colloids and because of the solids may partially shield organism from the disinfectant. In natural water bodies turbidity may impart born or other colour to water depending on the light absorbing properties of the solids, and may interfere with light penetration and photosynthetic reactions in stream and lake.
• The varying degrees of turbidity present can be classified as clear, dull, opalescent, markedly opalescent and distinctly turbid. These can be recognized by comparing samples with distilled water, keeping them in clear glass flasks, with gentle agitation and observing them against good diffused light.