Chloride levels in water can be considerably increased through specific treatment processes in which chlorine or chloride is used. This is a primary method by which human activities directly influence the chloride concentration in water sources.
The Role of Water Treatment Processes
Based on available information, a significant way to increase chloride in water is through its treatment. Water treatment plants, both for drinking water and wastewater, often utilize chemicals containing chlorine or chloride as part of their processes.
- Disinfection: The most common example is the use of chlorine-based disinfectants. When chemicals like chlorine gas (Cl₂), sodium hypochlorite (NaClO), or calcium hypochlorite (Ca(ClO)₂) are used to kill bacteria and viruses, they introduce chlorine into the water. As these chemicals react with water and organic matter, or simply decompose, they can break down to form chloride ions (Cl⁻), thereby increasing the overall chloride concentration in the water. For example, chlorine gas reacting with water produces hydrochloric acid (HCl), which dissociates into H⁺ and Cl⁻. Similarly, hypochlorite ions can ultimately convert to chloride ions.
- Other Chemical Additions: While less common as a method specifically intended to increase chloride levels in potable water, other treatment processes might use chemicals that contain chloride salts as part of their composition. If these are used in significant quantities, they could contribute to raising chloride levels, although the primary purpose of such chemicals is usually different (e.g., coagulation, pH adjustment, etc.). However, the reference specifically highlights processes where chlorine or chloride is used, strongly implying active chemicals or processes like disinfection.
Essentially, any water treatment activity that adds a chemical source of chlorine or chloride ions to the water will result in an increase in its chloride content. This is a direct outcome of the chemical reactions and additions employed during purification or sanitation stages.
In summary, the deliberate or incidental addition of chlorine or chloride compounds during water treatment is a key factor in raising chloride concentrations in water.
