To determine the taste and Odor value of given water sample
Discussion:
Odor
Water odor is mainly due to the presence of organic substance. Some odors are indicative of increased biological activity, others may originate from industrial pollution. Sanitary surveys should always include investigations of possible or existing sources of odor, and attempts should always be made to correct an odor problem.
The odor of drinking water may be defined as the sensation that is due to the presence of substances having an appreciable vapor pressure and that stimulate the human sensory organs in the nasal and sinus cavities. The sense of smell with generally responds to much lower concentrations (a few micrograms per liter or less of a substance than will be sense of taste (a few milligrams per liter).
The non specific fishy, grassy and musty odors normally associated with biological growth tend to occur most frequently in warm surface water in the warmer months of the year.
Taste
Generally, the taste buds in the oral cavity specifically detect inorganic compounds, such as magnesium calcium, sodium, copper, iron, and zinc. Certain salts, such as sodium bicarbonate and calcium chloride, must be present in the water at concentrations similar to those in the saliva to make the water seem tasteless.
Chlorination may produce chlorine residues that are perceptible by the consumer, but lowering the chlorine dose to overcome taste problems must not compromise the microbiological safety of the water.
Changes in the normal taste of a public water supply may point to changes in the quality of the raw water source or deficiencies in the treatment process. As water should be free of objectionable taste and odor for the majority of consumers, the guideline value is “not offensive to most of the consumers”
ODOR (Quantitative Estimation) –
Equipments / Glassware / Chemicals
Hot Plate. Erlenmeyer Flask 500 ml, Watch Glass, Pipettes, Activated Carbon Filter
Procedure
- Boil a quantity of distilled water until free from odor, or pass the water through a filter of activated carbon until odor-free. Cool to room temperature,
- Clean six 500-ml. Erlenmeyer flasks and remove the last traces of odor by boiling water in them for 5 min.
- Discard the water cool the asks and cover them with watchi glasses
- Determine the approximate odor as follows:
- Place 100 ml. of odor-free water, in each of two flasks..
- War to 60 °C and add to one flask 5 ml. of the sample.
- Shake both tasks vigorously. Remove the cover and determine if the water in the flask receiving the simple has an odor when compared with that in the other flask.
- If the odor is present, repeat using a smaller sample.
- knowing the approximate odor, a more accurate determination may be made as follows:
- Add 100 ml, of the odor-free water to each of the several flasks.
- Cover with watch glasses and warm to 60 °C.
- To the first live flasks add increasing volumes of the sample. Including the volume determined by the approximate method. For example, if the odor was found using 5 ml. of the sample in the approximate method odd 3, 4, 5, 6, and 7 ml, respectively, to the live flasks.
- Shake vigorously and determine the flask in which the odor first appears.
Note: If more than 5 ml. is required, reduce the volume of odor-free water used so that the total volume is not over 105 ml.
Calculations:
Result: