Engineering Board Exam Reviewer · Environmental Engineering · medium
The total hardness of water is 250 mg/L as CaCO₃ and the alkalinity is 180 mg/L as CaCO₃. What is the noncarbonate (permanent) hardness?
- 250 mg/L as CaCO₃
- 70 mg/L as CaCO₃
- 180 mg/L as CaCO₃
- 430 mg/L as CaCO₃
Answer
B. 70 mg/L as CaCO₃
Solution
When alkalinity < total hardness: carbonate hardness = alkalinity = 180; noncarbonate hardness = 250 - 180 = 70 mg/L as CaCO₃.
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