3.9 Metal Removal

Why is metal removal important in wastewater treatment?

• To enhance the aesthetic appeal of treated water.

• To prevent contamination of natural water bodies.

• To reduce the cost of wastewater treatment.

• To increase the pH of wastewater.

Which of the following metals is often targeted for removal due to its toxic nature in wastewater?

• Iron

• Aluminum

• Mercury

• Potassium

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

• To increase the pH of the wastewater.

• To convert dissolved metals into solid particles.

• To decrease the temperature of the wastewater.

• To increase the conductivity of the wastewater.

What is the most common method used for cyanide destruction in wastewater treatment?

• Chemical oxidation

• Biological treatment

• Physical adsorption

• Activated carbon filtration

Which chemical is commonly used for alkaline chlorination cyanide destruction?

• Sodium hypochlorite

• Hydrogen peroxide

• Potassium permanganate

• Ferric chloride

What is the purpose of adding a reducing agent in the Sulfur Dioxide (SO2) cyanide destruction method?

• To increase pH

• To neutralize residual chlorine

• To convert cyanide to thiocyanate

• To enhance reaction kinetics

What is the main advantage of using hydrogen peroxide for cyanide destruction?

• Rapid reaction rate

• Low cost

• Low toxicity

• Long shelf life

What is the major byproduct of the alkaline chlorination method for cyanide destruction?

• Ammonia

• Thiocyanate

• Nitrate

• Sulfate

Which cyanide species is more difficult to treat in wastewater due to its stability?

• Free cyanide (CN-)

• Complex cyanides

• Metal-cyanide complexes

• Organic cyanides

Which of the following cyanide destruction methods is suitable for batch treatment but not continuous flow systems?

• Electrochemical oxidation

• Alkaline chlorination

• Biological treatment

• Thermal treatment