A variety of disinfectants are available for hospital medical wastewater treatment, including ozone, ultraviolet (UV) radiation, sodium hypochlorite, chlorine dioxide, liquid chlorine, and bleaching powder. Among these, liquid chlorine and sodium hypochlorite are the most widely adopted. The rationale for this preference is analyzed as follows:
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Liquid Chlorine
Liquid chlorine is favored for its low cost, minimal requirement for complex equipment, and simple dosing operation. Its residual chlorine exhibits stable and lasting disinfection efficacy, making it a commonly used disinfectant for medical wastewater treatment across the world. However, it has notable limitations in terms of safety: chlorine is a hazardous gas, and leakage may cause harm to humans and animals. In addition, when the water source contains organic pollutants, excessive dosing of liquid chlorine may lead to the generation of harmful disinfection byproducts. For this reason, accurate control of chlorine dosage is essential. The RCl900 Online Total Residual Chlorine Analyzer can be applied to monitor and adjust chlorine levels in medical wastewater to achieve stable dosing control.
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Sodium Hypochlorite
Sodium hypochlorite is available in two forms: commercial-grade and on-site generated.
Commercial Sodium Hypochlorite: Supplied regularly by manufacturers, it generally contains 10% active chlorine. Most manufacturers add stabilizers to extend its shelf life from 1 week to more than 20 days. It is a safe, energy-saving, water-saving and easy-to-manage disinfectant for practical application.
On-Site Generated Sodium Hypochlorite: Produced by electrolytic generators with electricity and sodium chloride as raw materials. Under conventional conditions, the production of 1.0 kg of sodium hypochlorite consumes about 4 kW of electricity and 1–5 kg of salt. It can provide continuous residual chlorine disinfection effect and features higher safety compared with liquid chlorine, while its overall operational cost is slightly higher (disinfectant tablets can lower the cost to a certain extent). Nevertheless, this production mode requires regular cleaning of equipment electrodes with relatively high labor demand. In addition, hydrogen gas is produced during operation, which may bring explosion hazards when its concentration in the air exceeds the safe threshold.
For all types of disinfectants used in medical wastewater treatment, reasonable dosage control is essential. Meanwhile, standardized and continuous Monitoring of Medical Wastewater Quality should be carried out to ensure all indicators comply with relevant discharge standards before effluent discharge.
