Introduction to Environmental Engineering Code No. (PE389) Lec.
4
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Measurement of Water Quality-2
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physical parameters of drinking water quality.
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TURBIDITY Water that is not clear but "dirty," in the sense
that light transmission is inhibited, is considered turbid.
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COLOR AND ODOR Color and odor are both important measurements
in water treatment. Along with turbidity they are called physical
parameters of drinking water quality. Color and odor are important
from the standpoint of aesthetics (visual). If water looks colored
or smells bad, people instinctively (automatically) avoid using it,
even though it might be perfectly safe from the public health
aspect. Both color and odor may be and often are caused by organic
substances Color is measured by comparison with standards. When
multicolored industrial wastes are involved, such color measurement
is meaningless. Odor is measured by successive dilutions of the
sample with odor- free water until the odor is no longer
detectable. This test is obviously subjective and depends entirely
on the olfactory senses of the tester.
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SOLIDS Wastewater treatment is complicated by the dissolved and
suspended inorganic material the wastewater contains. In discussion
of water treatment, both dissolved and suspended materials are
called solids. The separation of these solids from the water is one
of the primary objectives of treatment.
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SOLIDS The usual definition of solids, however, is the residue
after evaporation at 103C (slightly higher than the boiling point
of water). The solids thus measured are known as total solids (TS).
Total solids are divided into two fractions: the total dissolved
solids (TDS) and the total suspended solids (TSS).
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SOLIDS Suspended solids are separated from dissolved solids by
filtering the water through a filter paper. The suspended material
is retained on the filter paper, while the dissolved fraction
passes through. If the initial dry weight of the filter paper is
known, the subtraction of this from the total weight of the filter
and the dried solids caught in the filter paper yields the weight
of suspended solids, expressed in milligrams per liter.
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SOLIDS Solids may be classified in another way: 1. Volatile
Solids. Those that are volatilized at high temperature (600C) 2.
Fixed Solids. Those are not volatilized at 600C. Volatile solids
are usually organic compounds. Obviously, at 600C, the temperature
at which the combustion takes place, some of the inorganics are
decomposed and volatilized, but this is not considered a serious
drawback. Measurement of the volatile fraction of suspended
material, the volatile suspended solids, is made by burning the
suspended solids and weighing them again. The loss in weight is
interpreted as the volatile suspended solids.
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Example Given the following data: Weight of a dish = 48.6212 g.
100 mL of sample is placed in a dish and evaporated. Weight of the
dish and dry solids = 48.6432 g. The dish is then placed in a 600C
furnace, then cooled. Weight = 48.6300 g. Find the total, fixed,
and volatile solids (expressed as mg/L).
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Questions Define turbidity? What is its importance and what is
the units of its measurement How can you determine color &
odor? Define pH? Mention two importance of determining pH? what is
the benefit of a high alkaline water? Mention the classification of
solids