November 23, 2016 10:30 pm
Acidity is the level of acid present in the waste water
Indicator Method
Pipette 20 ml or a suitable aliquot of sample into a l00-ml beaker. The sample size shall be so selected so that not more than 20 ml of titrant is needed for the titration. Determine the pH of water. If pH is less than 3.7, add two drops of methyl orange indicator into the first sample beaker and titrate with standard 0.02 N sodium hydroxide solution until the colour changes to the faint orange characteristic of pH 3.7. Record the volume of sodium hydroxide used. To the second sample beaker, add 2 to 3 drops of phenolphthalein indicator and titrate with 0.02 N sodium hydroxide solution to the appearance of faint pink colour characteristics of pH 8.3. Record the volume used.
Potentiometric Method
Pipette 20 ml or a suitable aliquot of sample into a 100 ml beaker. Acidity test with standard sodium hydroxide solution to pH 3.7 and pH 8.3. Record the volume of standard sodium hydroxide used. No indicator is required.
Calculation
Application of Acidity data
Carbon dioxide determinations are particularly important in the field of public water supplies.
Many underground supplies require treatment to overcome corrosive characteristics resulting from carbon-di-oxide. The amount present is an important factor in determining whether removal by aeration or simple neutralization with lime or sodium hydroxide will be chosen as the treatment method.
Most industrial wastes containing mineral acidity must be neutralized before they may be discharged to rivers or sewers or subjected to treatment of any kind.
Quantity of chemicals, size of chemical feeders, storage space, and costs are determined from laboratory data on acidity.
Conclusion
Acidity is thus an important factor in determining the quality of water which helps in determining the treatment method & the facilities needed.
Disclaimer
The details given are for general understanding. References should be taken from respective authorized agencies.