WTO - Water Treatment Operator Source Water Characteristics Questions and Answers

Question 1

A water treatment plant operator observes a sudden increase in turbidity in the raw water from a river source after a heavy rainfall. Which of the following is the MOST significant and immediate operational concern related to this change?

Accepted Answer

A reduced effectiveness of the disinfection process.

Answer

High turbidity, caused by suspended particles like silt and organic matter, can shield pathogenic microorganisms from disinfectants like chlorine. This shielding effect reduces the effectiveness of disinfection, posing a significant public health risk. The particles can also exert a higher disinfectant demand, consuming the disinfectant before it can inactivate pathogens.

Question 2

Which of the following BEST describes the primary cause of 'hardness' in a source water supply?

Accepted Answer

Dissolved mineral salts, primarily calcium and magnesium.

Answer

Water hardness is primarily caused by the presence of dissolved divalent cations, with calcium (Ca2+) and magnesium (Mg2+) ions being the most common contributors. These minerals are typically dissolved as water percolates through deposits of limestone, chalk, or gypsum.

Question 3

A groundwater well is showing consistently high levels of iron and manganese. Which physical characteristics would an operator most likely observe in the water before treatment?

Accepted Answer

Reddish-brown or black staining and a metallic taste.

Answer

Iron (Fe) and manganese (Mn) are common groundwater contaminants. When oxidized, iron produces a reddish-brown color, while manganese produces a brownish-black color. Both can impart an undesirable metallic taste and cause staining of laundry and plumbing fixtures.

Question 4

What does a high alkalinity measurement in source water indicate about its chemical characteristics?

Accepted Answer

The water is likely to be very soft.

Answer

Alkalinity is a measure of water's capacity to neutralize acids, or its buffering capacity. It is primarily caused by the presence of carbonate, bicarbonate, and hydroxide ions. High alkalinity means the water can resist changes in pH when an acid is added.

Question 5

A water utility is using a surface water reservoir as its source. Which of the following biological contaminants are of greatest concern for requiring filtration and disinfection treatment, especially in surface water?

Accepted Answer

Viruses and protozoa like Giardia and Cryptosporidium.

Answer

Surface water sources are open to the atmosphere and runoff, making them susceptible to contamination from human and animal waste. Pathogenic microorganisms, including viruses and chlorine-resistant protozoa like Giardia and Cryptosporidium, are a major health concern and a primary target for filtration and disinfection processes in surface water treatment.

(WTO) Water Treatment Operator Certification Practice Test

(WTO) Water Treatment Operator Certification Practice Test

WTO - Water Treatment Operator Source Water Characteristics Questions and Answers