Hospital sewage contains a large number of pathogens and toxic substances. It must be discharged into the sewer after effective treatment and purification measures.
What standards should be followed for hospital sewage treatment?
●In order to avoid pollution and damage during the transportation of hospital sewage, it is necessary to treat it on the spot in the hospital. It is strictly forbidden to arbitrarily discard hospital sewage and dirt into the sewer.
●Hospital sewage treatment should be classified and guided according to the nature, planning, sewage discharge destination, water pollution degree and regional differences of the hospital.
●Effectively remove toxic and harmful substances in sewage, reduce the occurrence of disinfection by-products during the treatment process, control excessive residual chlorine in the effluent, and maintain ecological and environmental safety.
●Fully consider the basic requirements for the discharge of sewage in comprehensive hospitals and epidemic hospitals, strengthen risk control awareness, and improve the ability to respond to emergencies from the aspects of process technology, engineering construction and supervision and management.
● The whole process of hospital sewage generation, treatment and discharge should be controlled; strict control and separation should be carried out at the source of sewage and pollutants, and domestic sewage in the hospital and sewage in the ward should be collected separately, that is, source control and clean and polluted diversion.
What is the process of hospital sewage treatment?
1. Sewage purification
Use hospital sewage treatment equipment to intercept and salvage floating objects; sediment and separate suspended objects; and degrade microorganisms through biological oxidation, so that the physical and chemical properties of the treated sewage meet the discharge standards.
2. Sewage disinfection
Sewage disinfection is mainly to kill pathogenic microorganisms in sewage. Chlorine or chlorine compounds are usually used as disinfectants in China and abroad to hydrolyze into useful chlorine such as hydrochloric acid and hypochlorous acid for sterilization. Commonly used chlorine disinfectants include liquid chlorine and bleaching powder, and chlorine generators can also be used to electrolyze salt water to produce hypochlorous acid.
Liquid chlorine is a strictly controlled toxic item with many purchase procedures. Because of its useful chlorine content and sterilization effect higher than bleaching powder and easy operation, it is the first choice for many hospitals with small discharge volume. During use, liquid chlorine is mixed with water through the vacuum chlorine injection machine to form hydrated chlorine, which enters the contact disinfection pool and is mixed with sewage for disinfection.
The amount of liquid chlorine needs to be effectively controlled. If the amount of chlorine is too small, the sterilization effect is poor. If the amount of chlorine is too large, it will corrode the pipeline equipment and cause chlorine pollution. Generally speaking, the amount of chlorine for primary treatment is about 30-50 mg/L, and the amount of chlorine for secondary treatment is about 15-25 mg/L. The actual amount of chlorine is adjusted according to the results of residual chlorine detection.
Liquid chlorine can cause chemical burns when it contacts the skin and mucous membranes. Therefore, chlorine bottles need to be explosion-proof and high-temperature resistant. The evaporation of chlorine gas is an endothermic process. When the evaporation amount is large, freezing occurs. If a leak is found, it can be temporarily treated by wrapping with a wet cloth or spraying with water. In severe cases, it can be pushed into a nearby alkaline water pool. Ammonia water and chlorine gas react to form white smoke of ammonia chloride, which can be used for leak detection.
3. Harmless treatment of sludge
This procedure mainly uses disinfection, fermentation and combustion to kill pathogenic microorganisms in the sludge discharged from the septic tank, sedimentation and biochemical treatment tanks. In order to make the sewage system work effectively, the sludge needs to be cleaned up regularly. The cleaning time is more than 3 to 7 months for septic tanks, and the adjustment, sedimentation and biochemical tanks are determined according to the sludge sedimentation situation.
Septic tanks have both sedimentation and digestion functions, and can mature sludge by anaerobic fermentation. In the septic tank, the organic pollutants in the sedimented sludge are decomposed by 40% to 50% under the action of anaerobic acid-producing bacteria, and the bacteria, worms and eggs are partially killed.
The sludge sorted out from each pool can be disinfected with chlorine water or mixed with quicklime to a pH value of 12, and then swept away after 7 days of storage. It can also be composted and fermented, using anaerobic bacteria and facultative anaerobic bacteria under anaerobic conditions to decompose organic pollutants and produce a high-temperature killing effect.
4. Sewage discharge detection
The laboratory staff of the sewage treatment station detects the residual chlorine and pH value of the treated sewage, and the other tests are conducted by the environmental protection and epidemic prevention departments. For residual chlorine, the staff on duty at the sewage station will test it at least twice a day; for fecal coliform group, the professional staff will test it at least once a month; for intestinal pathogens, the professional staff will test it at least twice a year; the commonly used method for detecting residual chlorine is the o-tolidine colorimetric method. For pH determination, fine pH test paper can be used to check.
