Chlorine disinfection is widely adopted in diverse industrial sectors thanks to its cost-efficient performance. Yet there exists a practical trade-off: chlorine can lower the activity of pathogenic microorganisms, while residual chlorine (particularly total residual chlorine, TRC) may bring potential risks to human health. This article delivers a concise analysis on this practical condition.
Mechanism of Chlorine Disinfection and Residual Chlorine Formation
Chlorine gas (Cl₂) refers to a yellow-green gaseous substance with sharp irritating odor and certain toxic properties, which carries notable bacteriostatic effects. Chlorination remains a common water treatment process for municipal tap water supply across China. Tap water generally maintains sanitary conditions, yet external environmental factors may encourage bacterial growth. To limit the reproduction of water-borne microbes, water treatment facilities add chlorine at set intervals with controllable concentration ranges.
Chlorine will engage in quantitative chemical reactions with bacteria, organic substances and other water contaminants — the chlorine consumption volume correlates with the content of harmful substances in water. In actual water treatment operations, it is hard to match chlorine dosage precisely to contaminant load. Unreacted chlorine remaining after disinfection procedures is defined as total residual chlorine (TRC). When TRC levels rise beyond reasonable ranges, human bodies may experience uncomfortable physical responses. For this reason, real-time monitoring via analytical equipment such as the RCl900 Online TRC Analyzer helps operators adjust chlorine dosing volumes appropriately.
Potential Health Concerns Triggered by Elevated Total Residual Chlorine
Higher TRC levels may create short-term and long-term physical discomfort for human bodies:
Short-term impacts: Residual chlorine may irritate the mucous membranes of eyes, nasal cavity, throat and upper respiratory tract, and in severe cases, lead to pneumonia or acute pulmonary edema. Under exceptionally high concentration scenarios, it may suppress respiratory nerve functions and create life-threatening conditions.
Long-term impacts: Continuous exposure to low-concentration chlorine gas may induce cumulative physical discomfort and accelerate cell aging processes. Regular intake of water with excess TRC may relate to dry, fragile hair, skin lightening and allergic reactions. Moreover, heating water containing surplus residual chlorine can generate disinfection byproducts (DBPs), several of which have been associated with elevated cancer risks based on existing research data.
It can be seen that adverse physical responses brought by poorly controlled residual chlorine after disinfection deserve adequate attention.
Application of RCl900 Online Total Residual Chlorine Analyzer
The RCl900 Online TRC Analyzer, developed by Hangzhou Modi, is mainly designed for monitoring wastewater from medical facilities. Analytic devices for municipal tap water and drinking water adopt similar structural frameworks, while they differ in targeted monitoring indexes: one focuses on total residual chlorine measurement, and the other targets free residual chlorine detection.
