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This post was last edited by Qingfeng Xuchi on 2022-2-11 at 10:09. Hospital wastewater comes primarily from areas such as the hospital’s treatment rooms, laboratories, wards, laundry rooms, X-ray rooms, and operating theaters; its sources and composition are quite complex. Hospital wastewater contains a large amount of pathogenic bacteria, viruses, and chemical agents, and is characterized by spatial contamination, acute transmission, and latent transmission. Compared to industrial wastewater, hospital wastewater is more harmful. During its operation, hospitals generate wastewater that is directly or indirectly infectious, toxic, or otherwise hazardous; this wastewater has a complex composition and contains various biological, chemical, or radioactive contaminants. In addition to containing a large number of pathogenic agents such as bacteria, viruses, and eggs, medical wastewater also includes chemical agents and radioactive isotopes. It presents several characteristics including environmental contamination, acute infection, and latent infection, making it highly hazardous. If medical wastewater containing pathogenic microorganisms is discharged directly into urban sewers without being treated to render it harmless through disinfection or inactivation, it often causes pollution of water and soil; in severe cases, it can lead to various diseases or the outbreak of water-borne infectious diseases. The wastewater generated by different departments and units varies in composition and volume, including heavy metal wastewater, oily wastewater, photochemical processing wastewater, radioactive wastewater, etc. Moreover, the wastewater generated by hospitals of different types also varies greatly. The discharge of hospital wastewater is more complex than that of ordinary domestic wastewater. The sources and composition of hospital wastewater are complex; in addition to ordinary domestic wastewater, it also contains chemicals, radioactive waste, and pathogens. Its COD and BOD values are generally lower than those of urban domestic wastewater, while its levels of E. coli and fecal coliforms are similar to those in medical wastewater; wastewater from certain departments contains pathogens of infectious diseases. Therefore, it must be treated before it can be discharged; in particular, wastewater from wards dealing with infectious diseases such as hepatitis, pneumonia, and the novel coronavirus must be disinfected and further treated before it can be released. In hospitals without centralized sewage treatment facilities, infectious feces must be disinfected separately to render them harmless. Common disinfectants include chlorine dioxide, bleaching powder, liquid chlorine, sodium hypochlorite, etc. Wastewater containing radioactive isotopes should be treated in accordance with the requirements for isotope treatment. During the treatment of hospital wastewater, disinfection is carried out first, followed by dechlorination using sodium thiosulfate, and then secondary biological treatment. Finally, the treated wastewater is disinfected once more in accordance with the regulations applicable to medical wastewater. Principles for hospital wastewater treatment 1. Principle of full-process control. Control the entire process of hospital wastewater generation, treatment, and discharge. 2. Principle of reduction. A strict internal hygiene and safety management system is implemented in the hospital, with strict control and separation at the sources of wastewater and waste. Domestic wastewater from the hospital and wastewater from the patient areas are collected separately, thereby achieving source control and separation of clean and dirty water streams. It is strictly prohibited to dispose of hospital wastewater and waste carelessly into the sewer system. 3. Principle of on-site treatment. To prevent pollution and harm during the transport of hospital wastewater, it must be treated on-site in the hospital. 4. Guiding principles for classification. Provide classified guidance for hospital wastewater treatment based on the nature and scale of the hospitals, the destination of wastewater discharge, and regional differences. 5. The principle of combining compliance with risk control. Fully considering the basic requirements for the compliant discharge of wastewater from general hospitals and infectious disease hospitals, while enhancing awareness of risk control, efforts should be made to improve the capacity to handle emergencies through aspects such as process technology, project construction, and supervision and management. 6. Principle of ecological security. It effectively removes toxic and harmful substances from wastewater, reduces the formation of disinfection by-products during treatment, controls excessive residual chlorine in the effluent, and safeguards the safety of the ecological environment.