Medical wastewater cannot be directly discharged and must be treated beforehand. This requirement has been emphasized repeatedly to remind relevant staff not to cut corners by discharging untreated medical wastewater directly, which would cause unnecessary harm. So, is disinfectant indispensable for medical wastewater treatment? Absolutely!
Disinfecting hospital premises is routine work, and medical wastewater disinfection is equally essential. Disinfectants are irreplaceable in medical wastewater treatment. Below is a brief introduction to several chlorination methods for medical wastewater treatment:
1.Sodium Hypochlorite Dosing Method (Sodium Hypochlorite Generator)
Sodium hypochlorite (NaClO) is one of the earliest wastewater disinfection methods. It is widely applied thanks to easy access to raw materials, stable and safe finished products, and convenient transportation.
Sodium hypochlorite is commercially available and can also be produced on-site. At present, small hospitals generally adopt the electrolytic salt method for on-site production of sodium hypochlorite. However, it features weak disinfection capacity and generates waste residue during treatment, so it is gradually being replaced by other disinfection products.
2.Liquid Chlorine Method
With strong disinfection performance and low cost, liquid chlorine is widely used in the disinfection of tap water and hospital sewage. It has an extremely high chlorine content of over 99%, 5 to 10 times higher than sodium hypochlorite solution.
Nevertheless, chlorine gas is a yellow toxic gas with a pungent odor, requiring dedicated storage and chlorination equipment. Typical chlorination equipment includes manual timing start-up type and automatic lift type.
Research data shows that liquid chlorine (Cl₂) reacts with ammonia to form monochloramine, dichloramine and trichloramine, consuming liquid chlorine. It also produces trihalomethanes (THMs) with carcinogenic risks, along with incomplete disinfection effects. For these reasons, the application of liquid chlorine disinfection is restricted.
3.Chlorine Dioxide Disinfection Method
The solubility of chlorine dioxide (ClO₂) in water is 5 times that of chlorine, and its oxidation capacity is about 2.15 times that of chlorine gas, making it a strong oxidant.
Recognized internationally as a high-efficiency disinfectant among chlorine-based disinfectants, it can kill all types of microorganisms, including vegetative bacteria, bacterial spores, fungi, mycobacteria and viruses.
It can effectively degrade trace organic pollutants in water such as benzopyrene, anthraquinone, chloroform, carbon tetrachloride, phenols, chlorophenols, cyanides, hydrogen sulfide and organic sulfides. It can also effectively oxidize reduced metal ions in water such as Fe²⁺, Mn²⁺ and Ni²⁺.
The outstanding advantages of chlorine dioxide are that it hardly produces volatile organic halides when reacting with humus and organic matter, does not generate and inhibits the formation of carcinogenic trihalomethanes, and does not react with ammonia and amino compounds.
Due to its chemical instability, chlorine dioxide is difficult to produce, transport and store, and generally must be generated on-site. Its main raw materials for preparation include chlorine-containing inorganic salts (mainly sodium hypochlorite, sodium chlorate, etc.) and chlorine gas.
In the process of medical wastewater treatment, medical wastewater monitoring must not be neglected. Water quality indicators are tested to evaluate the effect of disinfection and sterilization.
In addition, if chlorine-based disinfectants are used for wastewater disinfection, the total residual chlorine in the wastewater must be monitored simultaneously. The RCl900 Online Total Residual chlorine analyzer can monitor real-time changes of residual chlorine in water to ensure water quality safety.
