Explain in detail process of equalization and neutralization.

Mumbai university > Civil > SEM 8 > Industrial Waste Treatment

Marks: 10M

Year: May 2015, May 2014

1 Answer


  • It is the method of retaining waste in a basin so that the effluent discharge is fairly uniform in its characteristics.

  • The main objective is to minimize or control fluctuations in waste water characteristics in order to provide better condition for subsequent treatment.

  • The purpose of equalization is to provide adequate damping of organic fluctuations inorder to prevent shock loading of biological treatment.

  • It also provide adequate pH control or to minimize the chemical requirements for neutralization.

  • It helps in providing continuous feed to biological systems once a period, when the manufacturing plant is not operating.

  • It helps in preventing high concentration of toxic materials from entering the biological treatment plant.

  • There are 2 types of equalization:

    • Inline equalization: In the inline equalization all of the flow passes through the equalization basin. This arrangement can be made to achieve a considerable amount of constituent concentration and flow rate damping.

    • Offline equalization: In the offline arrangement only the flow above some predetermined flow limit is diverted into the equalization tank although the pumping requirement are minimized in this arrangement. The amount of constituent concentration clamming is considerably removed. Offline equalization is sometimes used to capture first flush from combined collection.


  • The excessively acidic or alkaline waste should not be discharged without treatment into a receiving stream, sewer, and effluent treatment plant or on land.

  • There are many acceptable methods for neutralization of acidic or alkaline waste water and they are as follows:

  • Neutralization of acidic waste:

    • Mixing the waste by the waste from other industry.
    • Passing acidic waste through beds of lime stone.
    • Mixing acidic waste with lime slurry
    • Adding proper proportion of caustic soda or soda ash.
    • Neutralization of alkaline waste:
    • Use of waste boiler flue gas
    • $CO_2$ treatment for alkaline waste
    • Producing $CO_2$ in alkaline waste
    • $H_2SO_4$ treatment
  • Acid waste neutralization in industrial process.

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