WTO Disinfection Processes 2

Question 1

What is the primary advantage of using chloramines over free chlorine for disinfection?

Accepted Answer

Chloramines produce fewer disinfection byproducts

Answer

Chloramines are stronger disinfectants

Answer

Chloramines work faster than free chlorine

Answer

Chloramines are cheaper to produce

Question 2

Which parameter most directly affects the disinfection efficiency of chlorine in water treatment?

Accepted Answer

pH

Answer

Water color

Answer

Water hardness

Answer

Turbidity alone

Question 3

A water system switches from free chlorine to chloramine disinfection. What operational concern must be addressed?

Accepted Answer

Nitrification in the distribution system

Answer

Increased formation of trihalomethanes

Answer

Higher turbidity in treated water

Answer

Reduced pH in finished water

Question 4

What does CT value represent in disinfection calculations?

Accepted Answer

Chlorine concentration multiplied by contact time

Answer

Contact time divided by chlorine dose

Answer

Temperature correction factor for chlorine

Answer

Chlorine demand at a given turbidity

Question 5

Why is ultraviolet (UV) disinfection considered ineffective against Cryptosporidium in terms of CT-based comparison?

Accepted Answer

CT tables do not apply to UV; UV efficacy is measured in mJ/cm²

Answer

UV does not inactivate Cryptosporidium at any dose

Answer

UV requires very high temperatures to work on Cryptosporidium

Answer

Cryptosporidium absorbs UV light and becomes stronger

Question 6

Which disinfectant is most effective for inactivating Cryptosporidium oocysts?

Accepted Answer

Ozone or UV

Answer

Free chlorine at typical doses

Answer

Chloramines

Answer

Chlorine dioxide at low doses

Question 7

A operator measures a chlorine residual of 0.0 mg/L in the distribution system. What is the immediate regulatory concern?

Accepted Answer

Potential violation of the Total Coliform Rule and surface water treatment requirements

Answer

Violation of the Lead and Copper Rule

Answer

Violation of the Arsenic Rule

Answer

Only a concern if turbidity also exceeds 1 NTU