Teknologi pengolahan air - Kuis 01

Particles smaller than 1 μm in water are called:

• Coarse particles

• Turbidity particles

• True colloids

• Dissolved solids

What is meant by sedimentation in water treatment?

• Separation of dissolved particles using membranes

• Separation of suspended solids from liquid through gravity

• Addition of chemicals for charge neutralization

• Removal of metal ions from water

The main purpose of the coagulation process in water treatment is:

• Lowering the pH of water

• Filtering dirt

• Neutralizing the charge of colloidal particles

• Adding nutrients

Flocculation involves:

• Lowering the temperature of water

• Redox reactions

• Formation of bridges between colloidal particles

• Deposition of metal ions

The chemical that is often used as an inorganic coagulant is:

• Calcium carbonate

• Aluminum and iron salts

• Silica and magnesium

• Sodium hydroxide

If in the jar test, floc does not form despite a high coagulant dose, the most likely cause is:

• Excess coagulant causes restabilization of particles

• Too strong agitation

• No suspended particles in water

• Too long sedimentation time

If a raw water has a large fraction of negatively charged colloids with neutral pH and low conductivity, the most effective initial treatment strategy is:

• Rapid filtration without pre-treatment

• Coagulation using anionic polyelectrolyte

• Addition of metal coagulant followed by slow flocculation

• Coagulation with strong base to raise pH

What is the main role of pH in the effectiveness of coagulation using alum (aluminum sulfate)?

• Determining flocculation time

• Affecting the isoelectric point of colloidal particles

• Controlling sedimentation rate

• Lowering TDS levels

The main difference between surface filtration and depth filtration is:

• Materials used

• Particle size

• Depth of the filter media that screens particles

• Operating temperature

One of the weaknesses of slow filtration systems is:

• Requires daily backwash

• Cannot remove color

• Requires very low flow rates

• Can only be used for seawater