Hospital wastewater refers to low-concentration sewage containing organic and inorganic substances, as well as a variety of viruses, bacteria and parasites, with complex compositional characteristics. Direct discharge of untreated hospital wastewater may cause contamination to surrounding water bodies and soil, and pose potential risks to human health. Therefore, standardized treatment and effective monitoring of hospital wastewater are of great practical significance. This paper briefly discusses the basic specifications for medical wastewater treatment and monitoring, as well as prevalent practical problems in operational processes.

Multiple disinfection technologies are currently applied in medical wastewater treatment. Taking chlorine disinfection as a typical example, this paper elaborates on its treatment process and corresponding monitoring requirements.

Core Specifications for Medical Wastewater Treatment and Monitoring

1. Complete wastewater disinfection treatment is a fundamental requirement. After disinfection, all water quality indicators shall be tested via professional monitoring equipment to ensure compliance with national discharge standards, with full attention paid to each indicator parameter.
2. Each treatment procedure is equipped with standardized time requirements. For instance, the hydraulic retention time of wastewater in septic tanks shall be no less than 36 hours, and operational procedures shall be implemented in accordance with specifications.
3. The dosage of different disinfectants is subject to standardized control to avoid excessive addition. For chlorine disinfectants, the recommended dosage is 30–50 mg/L for primary treatment and 15–25 mg/L for secondary treatment. Other types of disinfectants also follow corresponding dosage specifications for standardized application. Excessive chlorine dosage may produce harmful toxic and carcinogenic substances. Additionally, the residual chlorine concentration at the outlet of the contact tank shall be maintained within the range of 2–8 mg/L. Daily detection of total residual chlorine at the discharge outlet is required to control chlorine dosage within a reasonable range and avoid adverse effects from improper dosing. The RCl900 online total residual chlorine analyzercan achieve stable and accurate real-time monitoring for this indicator.
4. Coliform bacteria are a key monitoring indicator for medical wastewater. The monitoring frequency for coliform bacteria is lower than that of residual chlorine, with a regular detection cycle of at least once a month. Meanwhile, sampling and detection shall be conducted every four hours during daily operation to ensure the indicator meets standard limits. The Hangzhou Modi WECT-900 Online Coliform Analyzer can track dynamic changes of coliform bacteria in wastewater, providing effective data support for indicator control.

Prevalent Problems in Practical Operation (Three Typical Issues)

1. The number of hospital patients fluctuates periodically, leading to unstable wastewater flow. Fixed-timing disinfection dosing may fail to adapt to flow changes, easily resulting in substandard residual chlorine concentration or excessive coliform bacteria in treated wastewater.
2. Long-term use of highly corrosive chemical disinfectants may cause corrosion and damage to wastewater conveying pipelines. Timely inspection and maintenance are required; otherwise, pipeline leakage may occur, leading to the outflow of untreated wastewater before the completion of disinfection.
3. The overall workflow of wastewater disinfection and monitoring involves multiple sequential procedures, which requires standardized operation and effective coordination among staff to ensure the stable and orderly operation of the entire treatment and monitoring system.