Florida Drinking Water Operator "B" Practice Test

What organic matter reacts with chlorine to form trihalomethanes?

1. Artificial organic matter

2. Natural organic matter

3. Inorganic compounds

4. Chlorinated organic waste

The correct answer is: Natural organic matter

Natural organic matter is the correct answer because it contains various elements, such as humic substances and fulvic acids, that can react with chlorine during the water disinfection process. When chlorine is added to drinking water to kill harmful microorganisms, it can interact with this organic matter, resulting in the formation of trihalomethanes (THMs), which are a group of chemical compounds that include chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Understanding the significance of natural organic matter is essential, especially in water treatment processes, as the presence and concentration of this organic matter can directly influence the amount of THMs produced during chlorination. This is a critical factor for water operators to monitor, as THMs are regulated contaminants due to their potential health effects. In contrast, artificial organic matter refers to man-made substances that may not typically interact with chlorine in the same way as natural organic matter. Inorganic compounds do not contain carbon-hydrogen bonds and therefore do not become trihalomethanes upon chlorination. Chlorinated organic waste consists of already chlorinated compounds, which are not the primary source of THMs but may contribute to disinfection by-products in different contexts.