1.5 Chemical Precipitation

What is the primary purpose of chemical precipitation in wastewater treatment?

• Removing suspended solids

• Neutralizing the pH

• Removing dissolved ions and heavy metals

• Adding minerals to the water

What is the purpose of pre-precipitation in chemical precipitation processes?

• Enhancing precipitation efficiency

• Removing impurities before precipitation

• Increasing the pH of the solution

• All correct

Which of the following ions is commonly removed through co-precipitation in water treatment?

• Na+

• Cl-

• Fe3+

• HCO3-

Post-precipitation in chemical precipitation involves:

• Removing precipitates after the primary precipitation

• Increasing the temperature of the solution

• Adding precipitating agents after primary precipitation

• Decreasing the pH of the solution

What is the role of pH in chemical precipitation?

• pH influences the solubility of compounds and thus affects precipitation

• pH does not affect chemical precipitation

• High pH always leads to better precipitation

• Low pH always leads to better precipitation

Co-precipitation involves:

• Precipitating only the target ion

• Precipitating impurity ions before the target ion

• Precipitating a target ion along with other impurity ions

• All correct

The efficiency of chemical precipitation is influenced by:

• Temperature and pressure

• Time of the day

• Atmospheric humidity

• pH and concentration of reactants

Which of the following is a disadvantage of chemical precipitation?

• High efficiency in removing ions

• Environmentally friendly process

• Production of large amounts of sludge

• Low cost

What role does flocculation play in chemical precipitation?

• Breaking down precipitates into smaller particles

• Agglomerating fine particles into larger, settleable flocs

• Increasing the solubility of compounds

• All correct

Which of the following chemicals is used for pre-precipitation to prepare the solution for further treatment?

• Sodium hydroxide (NaOH)

• Sodium chloride (NaCl)

• Calcium carbonate (CaCO3)

• Sodium bicarbonate (NaHCO3)