Special Package of Chlorine Dioxide Powder for Aquaculture Water Treatment

Chlorine dioxide can be used for drinking water disinfection, decolorization, and deodorization; sterilization and algae removal in industrial circulating cooling water; and degradation and purification of harmful substances in industrial wastewater and domestic sewage. Traditional liquid chlorine and chlorine gas treatment of tap water can produce teratogenic or carcinogenic substances such as chloroform, chlorophenol, and chloramines. ClO2 _{, however} , does not undergo substitution reactions with organic matter in water to produce these toxic substances, thus attracting considerable attention. Since the 1950s, some European countries have begun using _ClO2 to replace chlorine as a water treatment agent. Through comparison of various disinfection methods, ClO2 is considered the most ideal disinfectant for controlling the production of toxic substances such as chloroform in tap water. Currently, developed European countries widely use _ClO2 as a water treatment agent, and more than ten water companies in China have also begun using it for water treatment _.

1. Application of chlorine dioxide in drinking water treatment

In the United States and Western Europe, almost all water treatment plants have replaced chlorine gas with chlorine dioxide for disinfection. Its characteristics include: the disinfected water tastes good, is safe and non-toxic, can degrade toxic substances, is convenient and safe to use, and has a lower overall cost. It is particularly suitable for use in rivers, lakes, and other bodies of water with high concentrations of humus and algae. Many small water treatment plants in China have already adopted stable chlorine dioxide for drinking water disinfection, and newly built large-scale water treatment plants are also beginning to use it.

Since the early 1990s, water pollution in my country has become increasingly serious, with deteriorating source water quality and exacerbated by secondary pollution, leading to a decline in tap water quality. With rising living standards and increased awareness of health, the quality of drinking water has become a major concern. Currently, most water plants in my country still use the traditional water treatment process of coagulation, sedimentation, filtration, and chlorination. Chlorination, using liquid chlorine, sodium hypochlorite, and bleaching powder, is not very effective at removing organic matter from water and generates various byproducts, including carcinogenic trihalomethanes (THMs). Developed countries in Europe and America have largely abandoned liquid chlorine disinfection, replacing it with chlorine dioxide and ozone to treat drinking water; some countries have even enacted laws and regulations mandating the use of chlorine dioxide. The use of chlorine dioxide for drinking water disinfection in my country is still in its early stages and requires further promotion and widespread adoption.

2. Disinfection effect on drinking water

Chlorine dioxide can kill all microorganisms in water. Its bactericidal effect is achieved by the chlorine gas released from its decomposition in water penetrating cell walls, effectively destroying enzymes containing sulfhydryl groups within bacteria, and rapidly controlling the synthesis of microbial proteins. Therefore, chlorine dioxide has a strong inactivation ability against bacteria and viruses. Its sterilization effect is 10 times that of chlorine gas and twice that of sodium hypochlorite. The effectiveness of chlorine dioxide in killing E. coli is not significantly affected even when the pH of the medium changes greatly. For example, for a bacterial medium containing less than 0.5 mg/L, at a pH of 6.5, both chlorine dioxide and chlorine gas can remove 99% of E. coli within 60 seconds. However, at a pH of 8.5, chlorine dioxide only needs 15 seconds to remove 99% of E. coli, while chlorine gas requires 5 minutes. Chlorine dioxide's ability to inhibit viruses is also 3 times higher than that of chlorine gas. If the dosage of chlorine dioxide is 0.20–0.25 mg/L, it can kill many viruses in water sources, such as Crohn's virus, herpesvirus, and Newcastle disease virus, within minutes, which is much better than the disinfection effect of chlorine gas.

3. Application prospects of chlorine dioxide in drinking water treatment in China

Drinking water disinfectants are a crucial aspect of water quality control, and their effectiveness is of paramount importance. Finding a broad-spectrum disinfectant with strong bactericidal ability, long-lasting disinfection performance, few byproducts (especially toxic byproducts), and safe and convenient use is a common goal for researchers. Humans began using chemical methods for disinfection in the early 19th century, initially using chlorine gas. After the invention of bleaching powder in 1820, it was successfully used for drinking water disinfection, marking the first milestone in chemical disinfection. Subsequently, second-generation disinfectants such as ethylene oxide and third-generation disinfectants such as glutaraldehyde were discovered . Chlorine dioxide is considered the fourth-generation disinfectant. Currently, the World Health Organization classifies it as an A1-level, broad-spectrum, and safe disinfectant, making it an internationally recognized ideal replacement for chlorine-based disinfectants. Its applications are increasingly broad, including industry, agriculture, food processing, cooling water treatment, dyeing wastewater treatment, healthcare, and environmental protection. Its potential for application in drinking water disinfection is particularly significant.

In my country, with rapid economic development, environmental pollution has become increasingly serious, especially the deterioration of the water environment. A 1999 environmental bulletin stated that major lakes in China suffered from severe eutrophication, and major rivers were widely polluted with organic matter. Chlorine dioxide is particularly suitable for water sources contaminated with organic matter. Therefore, the use of chlorine dioxide instead of chlorine in drinking water treatment in my country comprises three components: ① microbial control; ② control of scale and sediment; and ③ corrosion control. Microbial control is perhaps the most crucial aspect of cooling water treatment; failure to control microorganisms can lead to microbial contamination, metal corrosion, and the rotting of the wooden structure of cooling towers.

Water disinfection is now imperative. As early as the Ninth Five-Year Plan period, the Ministry of Construction included chlorine dioxide in its research and promotion of alternative disinfectants. Currently, cities such as Shanghai, Chongqing, and Wuhu have begun using chlorine dioxide for drinking water treatment.

The use of chlorine dioxide for drinking water disinfection in China is still in its early stages, and there are currently no nationwide standards for its application, particularly in drinking water disinfection. Much work remains to be done in standardizing the industry. The safety of chlorine dioxide in its preparation, storage, and transportation requires further research and improvement, and its price needs to be reduced. Therefore, replacing chlorine with chlorine as a drinking water disinfectant with chlorine dioxide still faces many challenges. However, with China's economic development, improved living standards, and increased environmental awareness, the replacement of chlorine with chlorine for drinking water disinfection is an inevitable trend, and it will make a greater contribution to human health.