发布时间：2022-07-02 09:47:07 人气：91 点赞：0
Hospital effluents, in addition to general domestic effluents, contain chemicals, radioactive effluents, and pathogens. Therefore, it must be treated before discharge, especially the effluent discharged from infectious disease wards such as hepatitis, and should be sterilized before discharge. Hospitals without centralized wastewater treatment equipment, with infectious feces, must be individually sanitized to render them harmless. Common disinfectants are chlorine dioxide, bleach powder, liquid chlorine, sodium hypochlorite, and ozone. For effluents containing radioactive isotopes, they should be treated according to the requirements of isotope treatment.
Hospital sewage during treatment, the precipitated sludge contains a large amount of bacterial, viral, and parasitic eggs, which should be sterilized (common slaked lime disinfection) or left behind by high-temperature composting to be used as fertilizer. The functions, facilities, and personnel composition of all departments in the hospital are different, and the main departments and facilities that generate sewage are: diagnosis and treatment rooms, chemical laboratories, wards, washing rooms, radiographic wash prints, animal rooms, isotope therapy diagnostics, operating rooms, and other drains. The domestic sewage discharged by hospital administration and medical staff, cafeteria, single quarters, family quarters. The composition and water volume of wastewater generated by different departmental departments are different, such as heavy metal wastewater, oily wastewater, wash printing wastewater, radioactive wastewater, and so on. And the sewage produced in hospitals of different nature is very different. The discharge situation of hospital sewage is more complicated than that of general domestic sewage.
The source and composition of wastewater in hospitals are complex, containing pathogenic microorganisms, toxic, harmful physicochemical pollutants and radioactive pollution, which have the characteristics of space pollution, acute infection and latent infection, and without effective treatment can become an important route for the spread of an epidemic disease and severely polluted environments. Therefore, hospital sewage tends to have the following characteristics:
The water quality of hospital effluents is characterized by the presence of a large number of pathogens - bacteria, viruses and parasite eggs. As TB hospital sewage, several hundred thousand to several million tuberculous bacilli can be detected per liter. Hospital effluents also contain many chemicals such as disinfectants, agents, and reagents. Effluents from hospitals utilizing radioisotope medical means also contain radioactive materials. The volume of sewage in a hospital is related to factors such as the nature, size of the hospital and the climate of the region in which it is housed, and generally ranges from 200 to 1000 l per bed per day. Hospital wastewater treatment is mainly disinfection, i.e. killing pathogens. Common methods are chlorination or disinfection with ozone (see disinfection of water, wastewater oxidative treatment method). Radioactive wastewater discharged from the hospital is commonly treated by the storage attenuation method. Commonly used radioisotopes in hospitals such as 131 iodine, 32 phosphorus, 198 gold, 24 sodium, etc. are isotopes with short half lives, so radioactive wastewater can be stored in dedicated underground decay tanks for a storage time of 10 times the half-life, lowering the radioactivity concentration to the extent that it is tolerated for discharge. If the concentration of radioactive wastewater is low and the amount of water is small, it can also be treated by dilution method. China's radiological protection regulations require that each micro Curie radioisotope reach the allowable emission concentration with a volume of diluted water of 1.67m 3. When the concentration of radioactive wastewater is very high and the half-life of radioactivity is so long that it is not easily treated by storage and dilution methods, it can be treated by evaporation, ion exchange, or coacervation precipitation (see radioactive wastewater treatment). The sludge drained during the wastewater treatment of a hospital is, according to each hospital bed, an average of 0.7-1 l per day, with 95% water content and 70-80% of the total amount of pathogens contained in the effluent, which must be treated with disinfection. Disinfection methods are heat and disinfect, chemical agents γ Ray disinfection et al. Heat sterilized heat sources are usually steam, electricity, or bioenergetics (high-temperature compost), and areas can be covered with solar energy. Or disposal by incineration (see sludge incineration). Chemical agent disinfection may be done using bleach powder, lime, ammonia, liquid chlorine or caustic soda, etc. The effective chlorine amount was about 2.5% of the sludge amount when bleaching powder or liquid chlorine. With basic agents, the pH of sludge reaches 12 and then remains more than half an hour with the best results. γ Radiographic disinfection may be used as a source of radiation with 60 cobalt or a mixture of some fission products at a radiation dose of 20-300 000 roentgenomes. Disinfection of sludge with this method does not produce stink gas and improves sludge dehydration and sedimentation, but at a higher cost. Therefore, hospital wastewater treatment often requires the following:
Principles of full process control. The complete process of wastewater production, treatment, and discharge from hospitals is controlled.
The principle of reduction. The internal hygiene and safety management system of the hospital should be strictly controlled and separated at the source of sewage and dirt generation, and the domestic sewage in the hospital should be collected separately from the effluent in the hospital area, that is, source control, and decontamination diversion. The ad libitum abandonment of effluents and dirt from the hospital into the sewer is strictly prohibited
Principles of in situ processing. To prevent contamination and hazards during hospital effluent delivery, in situ treatment is necessary in hospitals.
Classification guidelines. The classification of nosocomial wastewater treatment is guided by the nature, size, where the effluent is discharged, and regional differences.
Compliance combined with risk control principles. Comprehensive consideration of the basic requirements of the effluent standard discharge of comprehensive hospitals and infectious disease hospitals, while strengthening the awareness of risk control, from process technology, engineering construction, and supervision and management, to improve the ability to respond to unexpected events.
Principles of ecological safety. Effectively remove toxic and harmful substances from wastewater, reduce the production of disinfection byproducts in the treatment process and control the excessive remaining chlorine in the effluent, and protect the safety of the ecological environment.
Aerated biofilter method for hospital wastewater treatment
Hospital effluents mainly come from the effluents discharged from diagnosis and treatment rooms, wards, chemical and laboratory rooms, operating rooms, washing rooms, and administrative departments as well as cafeterias, quarters, etc., and the main contaminants are organic pollutants, pathogenic microorganisms and viruses. The hospital sewage is now only discharged by grid residue removal and disinfection and post-treatment, using chlorine dioxide disinfectant, chlorine residue and bacteriological indicators can be up to standard, but organic matter is not removed. In order to comprehensively meet the standard, the hospital has added an aerated biofilter wastewater treatment process to treat the sewage. Considering the limited footprint of the wastewater treatment plant in this hospital and the characteristic that water contains a certain amount of disinfectant, it was decided to adopt an Aerated Biofilter Process with high load, low footprint, and good adaptability to the organic concentration range of the influent.
The aerated biofilter has the following characteristics:
(1) High organic loading with little footprint
(2) Large biomass, high activity and shock resistance
(3) It has the dual function of biodegradation reaction and filtration without the requirement of a double sink cell
(4) High oxygen utilization due to the cleavage of the filter
(5) Operation stable and reliable, management convenient hospital wastewater treatment by the chlorination method
(1) Sodium hypochlorite method. Sodium hypochlorite is a common chemical reagent and is more convenient to transport, store and purchase. Sodium hypochlorite is soluble in water to produce hypochlorite ions, which can be used for disinfection and sterilization, but it is unstable, light, moisture is easy to break down, and the disinfection ability is very weak.
(2) Liquid chlorine method. Liquid chlorine in water can rapidly produce hypochlorite ions. This method has been widely used for wastewater disinfection in hospitals. The effective chlorine content in liquid chlorine is 5-10 times higher than that in sodium hypochlorite solution, and the disinfection capacity is strong and inexpensive. Since chlorine is a strong irritant toxic gas, it is to be stored with a dedicated storage facility.
(3) Chlorine dioxide method. Chlorine dioxide (ClO2) is a strong oxidant that is five times more soluble in water than chlorine, and its oxidizing capacity is about 215 times that of chlorine gas. It can kill all microorganisms while effectively destroying trace organic pollutants in water, and well oxidizes some metal ions in a reduced state in water. Its greatest advantage lies in the fact that reaction with humic substances and organics produces few divergent Organohalides, does not generate and inhibits the production of carcinogenic trihalomethanes, nor does it react with ammonia and amino compounds, thus making it very suitable for use in hospital wastewater treatment.
The non compliance of hospital wastewater treatment has always been an important factor that endangers the environment. After a long-term survey research on relevant departments has revealed that the following factors mainly contribute to the incomplete wastewater treatment in hospitals.
1. Triage the agents used in wastewater are all highly targeted in order to reduce costs. Thus, it causes the wastewater of each classification to be treated well, the comprehensive water or the treatment is not up to standard.
2. Use large quantities of lime for water quality clarity and for cost reduction. But it produces a lot of sludge, often 30% of the cost of waste water treatment - 40% is generated from treating sludge.
3. The pH value of the coming water varies greatly, and the pH control of the reaction pool is not stable. PH instability causes cloudy precipitate pools. The effluent water quality also follows the instability, time good and time bad.
4. Water handlers are not very responsible, the operations are not attentive enough, and do not pay attention to the details. For example: the coming water has problems, and do not stop in time for emergency treatment. Various gauges, probes are not routinely corrected for washing. Formulation the drug product concentration is not formulated according to the process requirements, and it is private to raise the concentration.
5. Products from the surface treatment industry must undergo extensive pre-treatment prior to surface treatment, which uses an emulsifier contained in the oil removal powder, and large amounts of emulsifiers not only affect the COD content, but also the alum flocculent of the precipitation tank, which is not ideal for sludge formation, resulting in poor precipitation, and a large amount of the suspension follows the upper clean water to flow out of the precipitation tank, redissolve the influent while pH callbacks, As a result, heavy metal ions in the discharge port are exceeded.
Treatment methods for medical wastewater
There are three categories of basic methods for the treatment of medical wastewater: physical, chemical and microbiological methods, at present, the more adopted methods in hospitals are chemical methods, and the physical methods mainly target hospital wastewater for precipitation, separation, cold and heat treatment and other operations. The chemical methods are more widely used in hospital wastewater treatment, and the current common methods include: chlorination disinfection method, oxidant disinfection method, radiation disinfection, etc., microbial treatment, as the current method of high added value to science and technology, has gradually been favored.
Precipitation filtration method
The precipitation method is an important aspect of the physical treatment of medical wastewater, and the main principle is to use different densities and contaminants of suspended wastewater in medical wastewater, in accordance with the principle of gravity sedimentation, to separate the suspended matter in medical wastewater. The filter medium is used to intercept the suspended material in sewage. There are steel bars, screen mesh, sand cloth, plastic, micro hole tube, etc., the commonly used filtration equipment is grid, gate, micro filter, sand filter, vacuum filter, press filter, etc., to separate the sewage.
In hospital medical wastewater treatment, wastewater containing suspended contaminated materials is rotated at high speed by a method that is separated due to different magnitudes of centrifugal force that the suspended particles (such as emulsified oil) and effluent are subjected to. The commonly used centrifugal equipment can be divided into two types according to the manner of centrifugal force generation: a vortex separator, which produces centrifugal force by rotation of the water flow itself, and a centrifugal separator, which produces centrifugal force by rotation of the equipment while also driving rotation of the liquid. Swirling separators are divided into two types, pressure and gravity. It has been widely used for wastewater treatment on rolled steel and pretreatment of river water with high turbidity in recent decades because of its advantages of small size and high treatment capacity per volume. There are many kinds of centrifuges, and there are regular speed centrifuges and high-speed centrifuges by separation factor. Chemical treatment methods chlorinated disinfection method chlorinated disinfection method is the most widely used method in our country. Common ones are sodium hypochlorite method, liquid chlorine method and chlorine dioxide method, etc. Sodium hypochlorite, which is relatively common chemical agent in medical use, is a light yellow transparent liquid with an pungent odor, which can be used and stored more conveniently, but it has instability, easy to decompose, weak disinfection ability, oxidation. This method is mainly used to treat medical wastewater in two ways: first, it is easy and convenient to dispose sodium hypochlorite or calcium hypochlorite in medical wastewater, which is less expensive and suitable for use in health institutes or township hospitals where medical wastewater is less produced. These hospitals have small numbers and simple waste water compositions, but it is difficult to accurately grasp the volume to be delivered because of the manual addition of pharmaceutics. The second is to use automatic sodium hypochlorite generator equipment for wastewater treatment, according to the waste water type and amount for automatic dosing agents, and the treatment effect is relatively stable. This method is relatively costly and highly demanding in technical staff quality, and it is suitable for large comprehensive hospitals with a larger number of patients and more medical wastewater. Its principle of disinfection: liquid chlorine in water can rapidly produce hypochlorite ions, and the chemical nature is active. The content of available chlorine in liquid chlorine is high, so the disinfection ability is strong, and it is widely used in the wastewater treatment of hospitals. Since chlorine is a strong irritant toxic gas, specialized storage equipment should be employed. Its principle of disinfection is: chlorine dioxide is a strong oxidant, which, when dissolved in water, will produce hypochlorite ions and chlorite ions, damage the body's absorption of iodine, and damage red blood cells. Chlorine dioxide is a highly effective fungicide that has been widely used in European and American countries since its application as a disinfectant for wastewater treatment. Chlorine dioxide generator, both in terms of installation and use
All have a lot of superiority, chlorine dioxide is bound to be one of the effective products for hospital medical wastewater treatment. Disinfection of medical wastewater using chlorine dioxide can effectively remove inactivated viruses, Cryptosporidium, etc., and chlorine dioxide disinfection is not affected by pH value and does not form organic halides such as chloroform. Chlorine dioxide can also effectively oxidize iron, manganese, sulfuric acid and many other organics, but again does not react with ammonia and does not form bromate. Contact the sewage treasure specifically or see http://www.dowater.com More relevant technical documents.
Oxidant disinfection method
Ozone is also a highly effective disinfectant, with an irritating odor, and it is unstable. Ozone has a high redox potential and is able to effectively explain organics, destroy cells that break down bacteria, and eventually kill cells. Ozone can eliminate microbes such as lifethreatening viruses and spores. After ozone treatment, the bacteria removal rate was up to 99.985% - 99.998%, the nitrite removal rate was 79.5%, and the removal rate of colority was 77%. Ozone sterilization is thorough and fast, and it is not affected by the external environment. But ozone disinfection also has some limitations, that is, ozone itself is unstable, can easily decompose in water, and ozone disinfection equipment is expensive.
Radiation disinfection method
Radiation disinfection mainly refers to the disinfection of disposable medical supplies using the ability of ionizing radiation to kill pathogenic microorganisms. Ultraviolet disinfection is one of the most economical and convenient methods, as well as a physical disinfection method, which uses the function of ultraviolet light to eliminate pathogenic microorganisms. The bactericidal disinfection effect of ultraviolet light at the wavelength (280-200 nm) was the best. The principle of ultraviolet disinfection for medical wastewater treatment: using the energy of ultraviolet photons to destroy the genetic material DNA of various viruses and bacteria in water, damage its DNA structure, and achieve the purpose of eliminating bacteria. The advantages of this medical wastewater treatment method are low cost, small investment, and short time.
Aerated biofilter method
Medical wastewater mainly comes from operating rooms, wards, washing rooms, etc., and its main contaminants are viruses, microorganisms and their organic contaminants. Disinfection such as using the chlorination method can be up to standard, but cannot effectively remove organic matter. In order to better control the sewage, and comprehensively to be up to standard, hospitals can also apply biofilter wastewater treatment methods, which is a novel biofilm based wastewater treatment process. Aerated biofilters have the following characteristics: less footprint and high organic loading; Because the filters have a cutting effect, the oxygen utilization is higher; Has a dual function of biodegradation reaction and filtration; High biological activity, large quantity and shock resistance; Run reliable and easy to manage.
Biological contact oxidation method
This method is a biofilm process intermediate between biofilters and activated sludge method. There is a filler inside the contact biological oxidation tank, to which the surface of the filler is attached microorganisms existing in the form of biofilms and some microorganisms existing in flocs, to use these biofilms and sufficiently win-win oxygen for the oxidative decomposition of organic matter in wastewater, and finally to achieve the effect of purifying water quality. Under biochemical conditions, the proposed method is efficient and energy-saving, small footprint, and convenient for operation. Biological contact oxidation methods are usually compared with conventional eliminationBiological contact oxidation methods are often used in combination with traditional disinfection methods. Such as the A / O secondary intensive biological contact oxidation process chlorine dioxide process and so on, these methods have been widely used in wastewater treatment in larger hospitals.
Membrane bioreactor treatment
In medical wastewater microbial treatment, membrane bioreactor treatment is a very common method, membrane bioreactor is mainly a novel water treatment technology that combines a biological treatment unit and a membrane separation unit, in this process, mainly membrane components are used to replace the traditional double sediment tank, which can achieve effective separation of solids and liquids and prevent the occurrence of sludge expansion, water quality instability., With the characteristics of high efficiency of water treatment, prevention of secondary pollution, strong sealing, less footprint, and rapid achievement, the membrane bioreactor treatment approach is the main aspect adopted for the current medical wastewater treatment.
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