Application of Chlorine Sensors in CL₂ Leak Detection in Waterworks

Chlorine disinfection for tap water is currently a common water treatment method worldwide. It can not only effectively eliminate harmful substances in water, but also is recognized globally as one of the efficient and reliable tap water treatment methods due to its low cost. However, with the continuous advancement of modern science, some scientists have proposed that tap water treated with chlorine may contain carcinogens, leading ordinary consumers to lose confidence in tap water quality. Nevertheless, some experts argue that the rational use of chlorine disinfection will not produce toxic substances; on the contrary, it can significantly reduce the cost of tap water treatment, thereby lowering the price of tap water for residents in China. So, does chlorine disinfection of tap water pose any harm to the human body?

Before understanding whether chlorine in tap water is harmful to the human body, we first need to learn about the main principle of chlorine disinfection for tap water:

The core principle of chlorine disinfection for tap water lies in generating chlorine gas through a chlorine dioxide generator. Chlorine is highly soluble in water. When chlorine reacts with water, it produces hypochlorous acid and hydrochloric acid. The generated hypochlorous acid exerts an ideal disinfection effect on microorganisms and pathogens in tap water. The disinfection effect of tap water treatment using a chlorine dioxide generator is superior to that of traditional bleaching powder disinfection and has gained wider recognition.

Then, is chlorine really harmful to the human body?

Firstly, chlorine gas itself does pose certain hazards to the human body. It can irritate organs such as the eyes, nose, and throat, potentially leading to acute pulmonary edema or pneumonia. When chlorine reaches a certain concentration, it can cause severe harm to the human body or even result in death.

However, the residual chlorine content in tap water treated by waterworks in China is far lower than the dose that can cause harm to the human body. Meanwhile, as a volatile chemical substance, chlorine gradually dissipates during the storage of tap water. Additionally, the modern lifestyle of residents also ensures that chlorine will not harm the human body. This is because residents in China usually have the habit of boiling tap water before drinking it. During the boiling process, chlorine in the tap water evaporates. Even if a small amount of residual chlorine enters the human body, it will be excreted through metabolism without causing any harm, let alone inducing cancer. Therefore, it is recommended that you avoid drinking raw tap water directly in daily life and try to boil it before consumption to improve the safety of tap water.

Waterworks draw water from rivers, lakes, and seas into the plant, and after a series of technological processes including coagulation, sedimentation, filtration, disinfection, and storage in clear water tanks, the water is pumped into tap water pipelines by high-pressure water pumps and then supplied to thousands of households.

Tap water is domestic and industrial water that meets certain standards after disinfection and purification. It is an essential guarantee for people's basic daily survival. The disinfection of tap water is directly related to water safety, which in turn affects the health of every user. There are various tap water disinfection methods, and currently, most waterworks in China adopt chlorine disinfection.

Chlorine disinfection has been in use for nearly 100 years due to its unique advantages. It offers excellent disinfection results even at low concentrations, with almost no harm to the human body. Moreover, it features low cost and mature, reliable process technology.

When chlorine is introduced into water (the chlorine dosage for disinfection is strictly regulated by national standards, with liquid chlorine ranging from 1.0 to 2.5g/m³), chlorine reacts with water to form hypochlorous acid, which has strong oxidizing properties.

Up to now, chlorine disinfection remains a relatively mature and widely used water treatment technology, and there is no method that can completely replace it for tap water disinfection. In fact, dozens of disinfection methods have been developed in the early days, such as bleaching powder and iodine. However, chemical disinfection is a double-edged sword, which inevitably produces certain side effects. Therefore, after comprehensive consideration, from the perspective of tap water safety, chlorine disinfection is a better choice.

Chlorine is a toxic gas with a yellow-green color and a strong pungent odor. Exposure to chlorine can cause symptoms such as sneezing, coughing, excessive tearing, and even suffocation. It mainly invades the human body through the respiratory tract and dissolves in the moisture of mucous membranes, generating hypochlorous acid and hydrochloric acid, which cause damage to the respiratory tract mucosa. Hypochlorous acid strongly oxidizes tissues, while hydrochloric acid irritates the mucosa, leading to inflammatory swelling, edema of the respiratory tract mucosa, and excessive mucus secretion, resulting in breathing difficulties. Therefore, a prominent symptom of chlorine poisoning is severe coughing. In severe cases, it can lead to pulmonary edema and subsequent death.

For algae and similar organisms in water, the strong oxidizing property of hypochlorous acid can destroy their cell walls, oxidize the enzymes inside them, and inhibit protein synthesis, thereby causing their death and achieving the disinfection purpose. However, hypochlorite carries a negative charge, resulting in suboptimal disinfection efficacy. For this reason, chlorine is used as a substitute for bleaching powder in disinfection.

Nevertheless, when using chlorine for disinfection, it is crucial to control the chlorine dosage. After all, chlorine is a toxic gas. It mainly enters the human body through respiration, dissolves in the moisture of mucous membranes, produces hypochlorous acid and hydrochloric acid, and damages the upper respiratory tract mucosa. Hypochlorous acid causes strong oxidation of tissues; hydrochloric acid stimulates inflammatory swelling of the mucosa, leading to edema of the respiratory tract mucosa and excessive mucus secretion, which induce breathing difficulties. Hence, a distinct symptom of chlorine poisoning is severe coughing. In critical cases, pulmonary edema may occur, causing circulatory failure and death. Therefore, it is essential to monitor chlorine content strictly when using chlorine disinfection. To address this issue, Shenzhen Wuliang Sensor Technology Co., Ltd. provides a solution: the adoption of the UK DDS Chlorine Sensor GS+4CL2 for real-time CL₂ concentration monitoring. Once the sensor detects that the chlorine content exceeds the preset range, it can immediately send out an alarm signal, enabling relevant staff to make timely adjustments.

From the above introduction, we can conclude that chlorine is highly toxic, but it has a dual nature and plays an important role in the development of human society.

The application of chlorine sensors in tap water disinfection has greatly improved the quality of human life and reduced the occurrence of discomfort. Compared with ozone, chlorine has significant advantages such as lower cost and mature technology, which are beneficial to residents' lives and help keep water prices affordable. With continuous technological upgrading, better tap water disinfection solutions will surely emerge in the future.