How to thoroughly remove Legionella in the hotel? Is there a better way? Please recommend it. Thank you.

Air-conditioning cooling tower is an important place for the growth and reproduction of Legionella and the main source of infection for people infected with Legionella. Strengthening the sanitary management of air-conditioning cooling tower system in hotels, restaurants, office buildings and other large buildings with centralized air-conditioning system can effectively reduce the chance of Legionella infection. Daily treatment and preventive measures include: ① When designing air conditioning system, avoid using fresh water cooling tower when it is economically and technically feasible [8]. ② Regularly clean the cooling tower system to keep it clean and reduce the formation of sediment and deposits. ③ Regular use of disinfectant pesticides. Traditional chlorine and bromine preparations are effective. When the residual chlorine concentration is 10-6, the growth of Legionella can be effectively inhibited. However, it should be noted that if it exceeds 10-6, the cooling tower pipeline system will be corroded, and excessive chlorine will easily form toxic compounds with organic substances to pollute the environment. When it is lower than 10-6, the purpose of inhibition cannot be achieved, and the residual chlorine concentration can be adjusted by regularly monitoring and controlling the pH value of water. Bromide is also an effective disinfectant. The effective concentration of bromine does not depend on the pH value like chlorine preparation, which is weak in corrosiveness and rarely produces harmful environmental pollutants [9]. (4) When the cooling water tower is in normal operation, the water will evaporate, while the dissolved substances will remain in the water system, thus increasing the total dissolved substances in the cooling water. The increase of total dissolved substances will lead to metal corrosion, chemical deposition and the growth of bacteria that rely on dissolved solids as nutrients. In order to solve these problems, a small part of water should be discharged (that is, discharged to the drainage pipe) and replaced by supplementary water, thus reducing the concentration of total dissolved substances [8]. ⑤ The injected water of cooling tower should be kept clean, which can reduce the formation of sediment, control the propagation of Legionella and improve the composition of disinfectant. ⑥ The cooling tower should be cleaned, dredged and disinfected regularly. The cleaning frequency depends on the pollution degree of the water tower and the individual site environment. As a guideline, the cleaning frequency should be set to every six months 1 time. If there is relevant performance data to support it, it can be cleaned at a long interval, but it should be cleaned at least 1 year. If the relevant data shows that it is necessary, it should also be cleaned at regular intervals [8]. ⑦ During the service life of cooling tower and evaporative condenser, laboratory tests, including the separation and concentration tests of Legionella, should be carried out to control the concentration of Legionella within a certain hygienic index. 2.2 Hot and cold water piping systems include drinking water, bathrooms, shower water, humidifiers and other water systems used in houses, workplaces, commercial institutions and factories. People are often infected by inhaling water contaminated by Legionella. The water temperature in the hot water system is often lower than 60℃, which often contains scale and sediment. Legionella is easy to breed and often causes people to be infected. Keep the water temperature at least 60℃ and the faucet at least 50℃ every day. Clean the faucet that is not often used before use. Drain the water in the hot water storage device regularly and clean it to avoid the accumulation of oxide, rust, scale and sludge. The number of cleaning depends on the speed of sediment and dirt accumulation in the equipment, and the speed of dirt accumulation mainly depends on the water quality of the water source. In general, it should be cleaned at least once a year 1 time [8]. Once Legionella is found positive and exceeds the standard in the laboratory test, we can take [9]: ① Raise the temperature of hot water above 70℃, keep it for 24 hours, and rinse the tap for 20 minutes. (2) Disinfect with chlorine preparation to keep the residual chlorine in the reservoir at 10-6 or smell obvious chlorine at the faucet. At the same time, the pH value of water is controlled to ensure the concentration of available chlorine. (3) After treatment, it can be used only after it has been tested in the laboratory and meets the health indicators. ④ Ozone, ultraviolet disinfection or metal ion ionization disinfection can also be adopted. ?