Understanding Chlorination Beyond Breakpoint

The question asks to identify the specific water treatment process that involves applying chlorine at levels exceeding the breakpoint chlorination point.

What is Breakpoint Chlorination?

Breakpoint chlorination is a critical concept in water treatment. It refers to the point in the chlorination process where all chlorine-demanding substances (like ammonia, organic matter, and reducing agents) in the water have been oxidized by the added chlorine. Beyond this point, any further addition of chlorine results in a proportional increase in the free chlorine residual in the water. This free chlorine is a powerful disinfectant.

Analyzing the Chlorination Processes:

• Prechlorination: This is the process of adding chlorine to raw water before it undergoes other treatment steps like sedimentation or filtration. Its primary goal is to reduce the formation of disinfection byproducts (DBPs) during later stages and to aid in coagulation. It does not specifically refer to chlorination beyond the breakpoint.
• Super chlorination: This process involves adding a dose of chlorine significantly higher than that required to reach the breakpoint. The water is chlorinated well beyond the breakpoint. The purpose of super chlorination is to ensure the oxidation of troublesome compounds that cause taste and odor problems, remove color, and kill resistant microorganisms. After super chlorination, the excess chlorine is typically removed through a dechlorination process (e.g., using sulfur dioxide). This definition directly matches the description "chlorination beyond break point chlorination".
• Post chlorination: This involves adding chlorine after the water has been treated and filtered. Its main purpose is to maintain a disinfectant residual in the water as it travels through the distribution system, preventing recontamination. It aims for a specific free chlorine residual, not necessarily beyond the breakpoint.
• Dichlorination: This term is not a standard process name in water treatment concerning stages of chlorination relative to the breakpoint. It might refer to the use of specific chlorine compounds or a secondary chlorination step, but "super chlorination" is the established term for chlorinating beyond the breakpoint.

Conclusion:

Based on the definitions, the process specifically described as involving chlorination beyond breakpoint chlorination is Super chlorination. This technique utilizes a high chlorine dose to tackle specific issues like taste and odor, ensuring comprehensive treatment.