Neutralization Quiz

Neutralization is the treatment of industrial waste to adjust its pH to a level that is neither too acidic nor too alkaline for safe discharge. It is important because excessively acidic or alkaline wastes can adversely affect receiving streams.

The volume, kind, and quality of acid or alkali to be neutralized are factors in deciding which neutralizing agent to use.

It is critical to consider the overall cost because material costs vary widely and equipment for utilizing various agents will differ with the method selected.

Mixing of wastes can be accomplished within a single plant operation or between neighboring industrial plants. Proper mixing of acid and alkaline wastes at appropriate times can accomplish neutralization, although this usually requires some storage of each waste to avoid slugs of either acid or alkali.

1. Mixing wastes to achieve a neutral pH, 2. Passing acid wastes through beds of limestone, 3. Mixing acid wastes with lime slurries, 4. Adding concentrated solutions of caustic soda (NaOH) or soda ash (Na₂CO₃) to acid wastes, 5. Adding compressed CO₂ to alkaline wastes, 6. Adding sulfuric acid to alkaline wastes.

A stream is adversely affected by low or high pH values, and this adverse condition is even more critical when sudden sludge of acids or alkalis are imposed upon the stream.

A reservoir ahead of an anaerobic digestion pond can be used to mix various types of plant wastes before treatment. The resulting pH of the reservoir effluent ranged from 6.5 to 8.5.

It requires some storage of each waste to avoid slugs of either acid or alkali.

Adding compressed CO₂ or adding sulfuric acid to alkaline wastes.