Question 1006 of 229 · California Water Distribution Operator Exam
Heavily chlorinated water flushed from a main must be dechlorinated before it reaches a storm drain or creek. Which chemical is commonly used?
Exactly one answer is correct.
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Correct answer to question 1006
- C: Sodium thiosulfate
Explanation
Reducing agents such as sodium thiosulfate, sodium bisulfite, sulfur dioxide or ascorbic acid neutralize chlorine. Hypochlorite adds chlorine, and lime and alum do not remove it.
More questions: Disinfection
- 1007Approximately what percentage of available chlorine does calcium hypochlorite (HTH) contain?
- 1008Which form of chlorine is 100 percent available chlorine?
- 1009A chlorine dose of 3.0 mg/L produces a free chlorine residual of 0.8 mg/L after the contact time. What is the chlorine demand?
- 1010Which substances commonly create chlorine demand in a distribution system?
- 1011The total chlorine residual equals which combination?
- 1012Which test is most often used by operators in the field to measure chlorine residual?