Hospital sewage technical solution: water volume calculation, disinfection technology, Tushan environmental protection

2022-06-08 0 By

Chapter I Introduction to hospital sewage 1.1 Nature of hospital sewage 1.1.1 Sources and Main pollutants Of hospital sewage The main departments and facilities of hospital sewage discharge include: consulting room, laboratory, ward, laundry room, X-ray printing, animal room, isotope therapy diagnosis, operating room, etc.In addition, there are dining halls, family dormitories and other discharge of sewage.One of the main pollutants in hospital sewage is pathogenic microorganism.The second is toxic, harmful physical and chemical pollutants, including conventional organic pollutants with COD, BOD5 expression: the third is radioactive pollutants.Table 1 shows the drainage situation and main pollutants in each department of the hospital.1.1 Amount of Hospital Sewage According to gbJ15-88 Code for Design of Building Water Supply and Drainage and GBJ49-88 Code for Architectural Design of General Hospital, the water consumption of hospitals, sanitariums and other facilities is shown in Table 2.According to the design code for hospital sewage treatment, the displacement of general hospitals is as follows :(1) the average daily sewage volume of large hospitals with well-equipped equipment is 400 ~ 600L/ (bed d), K= 2.l ~ 2.2;(2) For small and medium-sized hospitals with general equipment, the average daily sewage volume is 300-400L/(bed d), K= 2.2-2.5;(3) The average daily sewage volume in small hospitals was 250-300L/bed d, K=2.5.Chapter II Hospital Sewage Disinfection Process In hospital sewage treatment, the use of physical or chemical methods to kill pathogenic bacteria and other harmful microorganisms in the water, so that the number of microorganisms in the water to meet the requirements of human health process, is called disinfection.Disinfection method is very much at present, tell from classification, can divide for physical method and chemical method two kinds, physical law has heat disinfection, freeze, radiation, ultraviolet ray disinfection, ultrasonic disinfection lamp, chemical law adds chlorine or chlorine ammonia method disinfection and ozone disinfection.At present, chemical method is usually used in China.There are many kinds of disinfectants commonly used in chemical treatment of hospital sewage, which can be mainly divided into chlorinated disinfectants and oxidized disinfectants.Chlorinated disinfectants mainly include liquid chlorine, bleaching powder, bleaching powder essence, triplet two, sodium hypochlorite, etc., among which liquid chlorine and sodium hypochlorite are more commonly used.Chlorinated disinfectants mainly react with water to generate hypochlorous acid, which has strong bactericidal ability, thus killing harmful bacteria in sewage.The most important technology in hospital sewage treatment is disinfection to kill all kinds of pathogenic bacteria in sewage.Disinfection mainly includes ozone disinfection, liquid chlorine disinfection, ultraviolet disinfection, chlorine dioxide disinfection and other processing technology.1.1 Ultraviolet disinfection Ultraviolet disinfection is not to kill microorganisms but by removing its reproductive ability to eliminate, is a physical disinfection method.The ultraviolet rays used for disinfection are c-wave ultraviolet rays with wavelengths ranging from 200 nm to 275nm, and 250-270 nm is the most effective for sterilization.Ultraviolet disinfection technology is the use of special design of high power, high strength and long service life of c-band ultraviolet generator produces strong uv light water, make all sorts of bacteria, viruses, parasites in the water, algae and other pathogens by ultraviolet C irradiation dose, the DNA structure in cells from damage and loss of activity,Thus kill bacteria, viruses and other pathogenic bodies in water, to achieve the purpose of disinfection and purification.Because ultraviolet sterilization has the advantages of fast speed, good effect and no secondary pollution, it is a new generation of disinfection technology in the world.However, the concentration of suspended matter in water is required to be low to ensure good light transmittance.Ultraviolet disinfector structure there are two forms: (1) open structure: sewage under the action of gravity through UV disinfector microorganisms are killed.(2) Closed structure: closed UV sterilizer is a pressure type, with a metal cylinder and quartz tube UV lamp to be sterilized water closed.If the ultraviolet disinfection process is used in untreated or only primary treated sewage (SS high 30mg/L sewage), it will not only increase energy consumption but also cause poor disinfection effect, that is, it is not suitable for water with low uv penetration.1.2 Liquid chlorine disinfection (CL2) Liquid chlorine disinfection is the most common one in hospital sewage disinfection. Its principle is to add liquid chlorine (CL2) or hypochlorite (such as NaCLO) to the water.Chlorine is a strong oxidant and broad spectrum fungicide, not only effectively kill bacteria and viruses in sewage, and can continue to disinfect.Liquid chlorine disinfection system is mainly composed of chlorine storage cylinder, chlorine machine, water injector, solenoid valve, chlorine pipe, chlorine room and liquid chlorine storage room.When disinfection, chlorine will react with ammonia nitrogen and organic nitrogen in water to produce inorganic chloramine and organochloramine with poor disinfection effect, known as combined chlorine.The disinfection effect of chlorine is affected by exposure time, dosage, water quality (nitrogen compound concentration, SS concentration), temperature, pH and control system.The biggest advantage of liquid chlorine disinfection is that the process is simple, the technology is mature, the reagent is easy to obtain, the dosage is accurate, and it has the following disinfection effect and the raw material is cheap, the sterilization force is strong, and it does not need huge equipment.However, because chlorine gas is toxic and corrosive, it should be avoided as far as possible in operation and management.The scope of application of liquid chlorine disinfection: ① For large scale (>1000 beds) and high management level of hospital sewage treatment system far away from the population settlement.② When hospital sewage is discharged to surface water or used as water for greening, chlorine disinfection should not be applied, because the excess chlorine in the water after chlorine disinfection will cause the death of aquatic organisms in surface water.1.3 Ozone disinfection (O3) Ozone (O3) is an allotroph of oxygen (O2). Pure O3 is a blue gas with a special pungent odor at room temperature and pressure. It is internationally recognized as a green disinfectant.Ozone sterilization process is a physical, chemical and biological reaction.It has the following three functions: ① Ozone can oxidative decomposition of bacteria internal oxidation of glucose necessary enzymes, so that bacteria inactivated death.② Directly interacts with bacteria and viruses to destroy their cell walls, DNA and DNA, and the metabolism of bacteria is destroyed, resulting in death.③ Can penetrate the cell membrane tissue, invade the membrane of lipoprotein on the outer membrane and the internal lipopolysaccharide, so that the bacteria have permeability distortion, dissolve death.Ozone disinfection has the following advantages: first, fast reaction, less dosage;Secondly, it has strong adaptability, no secondary pollution and stable disinfection performance in the range of pH5.6 ~ 9.8 and water temperature 0 ~ 37℃.Finally, ozone disinfection is not affected by NH3 and pH in sewage, which can not only oxidize organic matter, but also sterilize and remove color, smell, taste, etc., and its final products only carbon dioxide and water, do not produce carcinogens.But ozone disinfection also has its disadvantages, such as: no continuous disinfection function, can only be used in field production, ozone disinfection method equipment cost is higher, power consumption is larger.1.4 Chlorine dioxide disinfection (CLO2) The only highly effective disinfectant in chlorine-containing disinfection recognized internationally is chlorine dioxide.The reasons are as follows: first, chlorine dioxide is highly oxidizing (5 times more soluble in water and about 2.5 times more oxidizing than chlorine gas), and second, it is very safe when dissolved in water.Due to the unstable nature of the actual need to use chlorine dioxide generator field preparation, chlorine dioxide generator mainly has two kinds: ① to sodium chlorate, hydrochloric acid as raw material compound chlorine dioxide generator;② Pure chlorine dioxide generator with sodium chlorite and hydrochloric acid as raw materials.Compound chlorine dioxide generator is a mixture of sodium chlorate and hydrochloric acid to prepare chlorine dioxide, supplemented by chlorine gas, which is most widely used at present.Its scope of application is: (1) away from the population settlement, small-scale hospital sewage treatment system, is not suitable for densely populated areas and large-scale hospital sewage disinfection.② It is suitable for the hospital sewage treatment system with high management level, because the concentration of chlorine dioxide in air and water will explode when it reaches a certain level.③ It is suitable for large scale (not less than 500 beds) hospital sewage treatment disinfection system.④ When the hospital sewage should be discharged to the surface or used as irrigation water, chlorine dioxide should be carefully used for disinfection.Although chlorine dioxide has many advantages, the preparation of chlorine dioxide with low chlorine content is complicated and NaClO2 is more expensive than other disinfection methods, so it is not widely used.