Question

Why liquids like grease, oil and soap rise to the top in sedimentation tank?​

Answer 1

Answer:

Because oil is less dense than water, it will always float on top of water, creating a surface layer of oil. ... As a result, detergents can bind to both water and oil molecules

Answer 2

Answer:

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Removal requires chemical addition to lower the pH followed by addition of dissolved oxygen or nitrogen to remove the emulsified oils as they break free from the wastewater. Dissolved Oil is a true molecular solution within the water and can only be removed with biological treatment.