The disinfection of hospital wastewater is a critical measure for healthcare facilities to control the spread of pathogenic microorganisms. By eliminating harmful substances such as pathogenic bacteria and viruses in wastewater, the water quality is improved to meet China’s national wastewater discharge standards prior to discharge. Among various indicators, coliform bacteria serve as one of the key metrics for evaluating the disinfection efficacy of medical wastewater. This paper focuses on the monitoring and analysis of coliform bacteria in medical wastewater.
First, it is essential to clarify the primary habitat of coliform bacteria: they colonize the intestinal tracts of humans and warm-blooded animals, forming a group of enteric bacteria that are excreted with feces. When water sources are heavily contaminated with fecal matter, they will contain high concentrations of coliform bacteria. Such contamination is common in medical wastewater; if discharged without adequate disinfection, it poses significant risks to human health and the environment. Therefore, during medical wastewater treatment, in addition to implementing disinfection and sterilization processes, systematic Wastewater Monitoring is imperative. Monitoring coliform bacteria specifically aims to assess the extent of fecal contamination in the wastewater.
Notably, monitoring requirements vary across different types of hospitals. Relevant authorities should implement targeted supervision, with a focus on establishing robust disinfection systems, enforcing strict management protocols, and ensuring high compliance rates in monitoring. A lack of disinfection awareness among staff may lead to low operational efficiency of wastewater treatment facilities, thereby reducing the compliance rate of coliform bacteria in discharged wastewater. Additionally, most medical institutions use chlorine-based disinfectants, which exhibit poor stability and tend to decompose at high temperatures in summer, resulting in reduced concentration and diminished sterilization efficacy—this also contributes to lower compliance rates for coliform bacteria. It is crucial to emphasize the significance of this issue.
Regarding the testing procedure: prior to formal analysis, staff first measure residual chlorine, neutralizing it using a 5% sodium thiosulfate solution. Subsequently, an appropriate volume of the treated sample is inoculated and incubated. The evaluation criteria for coliform bacteria in water are primarily based on the national standard GB 18466-2005 Emission Standards for Wastewater from Medical Institutions.
In terms of monitoring methods, the enzyme substrate method is applicable. The WECT-900 Online Coliform Analyzer manufactured by Hangzhou Modi utilizes this method, which is based on the principle that the change in optical signals is proportional to the bacterial content in the sample following the enzymatic reaction with bacteria.
