Which one of the following method is used for the estimation of the chlorine demand of water?
**Core Concept**
The chlorine demand of water refers to the amount of chlorine required to oxidize the organic and inorganic impurities present in the water. This is an important concept in water treatment, as it helps determine the amount of chlorine needed to achieve a safe and effective disinfection.
**Why the Correct Answer is Right**
The correct answer involves the concept of chlorine demand, which is typically measured using a method called the "chlorine demand test". In this test, a known amount of chlorine is added to a sample of water, and the residual chlorine concentration is measured after a specified contact time. The chlorine demand is then calculated as the difference between the initial amount of chlorine added and the residual chlorine concentration. This method is widely used in water treatment plants to ensure that the water is adequately disinfected.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not relate to the estimation of chlorine demand. Chlorine demand is a critical parameter in water treatment, and it is not measured using a method that simply adds chlorine to the water without considering the contact time or residual concentration.
**Option B:** This option is incorrect because it refers to a method of measuring chlorine residual, not chlorine demand. While chlorine residual is an important parameter in water treatment, it is not directly related to the estimation of chlorine demand.
**Option C:** This option is incorrect because it refers to a method of measuring pH, not chlorine demand. pH is an important parameter in water treatment, but it is not directly related to the estimation of chlorine demand.
**Clinical Pearl / High-Yield Fact**
A common mistake in water treatment is to add too little chlorine, which can lead to inadequate disinfection and the presence of harmful bacteria and viruses in the water. To avoid this, it is essential to accurately measure the chlorine demand of the water to ensure that the correct amount of chlorine is added.
**Correct Answer: B. Nephelometric Turbidity Units (NTU) measurement is not relevant to the estimation of the chlorine demand of water.