advantage
Generally, ultraviolet disinfection can be used in areas where the supply of chlorine and hypochlorite is difficult, and where there are strict restrictions on the disinfection by-products of chlorine after water treatment. It is generally believed that UV disinfection is more economical when the water temperature is low.
The advantages of UV disinfection are as follows:
No impurities are introduced in the water, and the physical and chemical properties of the water remain basically unchanged;
The chemical composition of the water (such as chlorine content) and temperature changes generally do not affect the disinfection effect;
Do not increase the smell and taste in the water, and do not produce disinfection by-products such as trihalomethane;
The sterilization range is wide and rapid, and the treatment time is short. Under a certain radiation intensity, the general pathogenic microorganisms can be killed in only ten seconds. It can kill some bacteria that cannot be inactivated by the chlorine disinfection method, and can also control some of them to a certain extent. Higher aquatic organisms such as algae and bloodworms;
Excessive treatment generally does not cause water quality problems;
The integrated equipment is simple in structure, easy to install, compact and light, with little head loss and less land occupation;
It is easy to operate and manage, easy to realize automation, and the equipment operation and maintenance workload of a well-designed system is very small;
Operation and management are relatively safe, and there are basically no potential safety hazards such as toxic, flammable, explosive and corrosive that may be caused by the use, transportation and storage of other chemicals;
The disinfection system has no other noise source except the pump that must be running.
Disadvantage
Spores, cysts and viruses are more tolerant than autotrophic bacteria;
Water must be pre-treated, because ultraviolet rays will be absorbed by many substances in the water, such as phenols, aromatic compounds and other organic substances, certain organisms, inorganic substances and turbidity;
There is no continuous disinfection ability, and there may be a problem of microbial light resurrection. It is best used in the occasions where the treated water can be used immediately, the pipeline has no secondary pollution and the raw water biological stability is good (generally, the organic content is required to be less than 10μg/ L);
It is not easy to achieve uniform radiation in the entire processing space, with illuminated shadow areas;
There is no residual property that is easy to detect, the treatment effect is not easy to determine quickly, and it is difficult to monitor the treatment intensity;
Shorter-wavelength ultraviolet (less than 200nm) irradiation may convert nitrate into nitrite. In order to avoid this problem, special lamp materials should be used to absorb wavelengths in the above range.
