UV light plays a key role in numerous commercial and industrial water filtration applications. In these applications, raw or feed water is often contaminated with microorganisms. UV light can penetrate the cell walls of microorganisms, disrupting the cellular structure and thus effectively preventing them from replicating. This approach ensures that microorganisms do not cause human infections and do not pose a hazard to the end product or processing equipment.
What’s UV?
Ultraviolet disinfection is a process that utilizes the ability of ultraviolet (UV-C) radiation to kill bacteria, viruses, fungi, and other microorganisms. It is a type of electromagnetic radiation that lies beyond the violet end of the visible spectrum.UV-C is part of the ultraviolet spectrum, which typically ranges in wavelength from 280 to 100 nanometers, and is highly energetic, destroying the genetic material of microorganisms, thereby preventing them from reproducing and causing infections.
Ultraviolet Disinfection Working Principle
The principle of UV disinfection is that by exposing an object or fluid to UV-C light, photons penetrate the cell walls and nucleic acids of microorganisms, causing damage to DNA or RNA and preventing their replication and growth. In this way, the microorganisms lose their ability to survive and spread, thus realizing the disinfection effect.
UV disinfection is widely used in the fields of wastewater treatment, air purification, medical equipment disinfection, food industry, and laboratory. Compared with chemical disinfection methods, UV-C disinfection has some advantages, such as no need to add chemicals, no by-products produced, and easy operation. However, it should be noted that the intensity of UV-C light and exposure time have an impact on the disinfection effect, so it is necessary to be careful when using the operation.
What does UV sterilization remove?
Outside-line water treatment disinfection mainly through ultraviolet (UV-C) radiation to destroys the genetic material of microorganisms, to achieve the purpose of killing bacteria, viruses, fungi, and other microorganisms. UV water treatment disinfection has a better bactericidal effect on a variety of microorganisms in water, including but not limited to:
- Bacteria: Bacteria including E. coli, Salmonella, etc.
- Viruses: e.g. Norovirus, Adenovirus, and other waterborne viruses.
- Fungi and spores: e.g. molds, yeasts, etc., and their spores.
- Parasite eggs: Includes eggs of all types of parasites, such as various worms.
- Other microorganisms: including algae, cyanobacteria, etc.
UV water treatment primarily targets the DNA or RNA of microorganisms, and therefore does not have a direct removal effect on water contaminants of a physical nature such as chemicals, dissolved substances or suspended matter. UV water treatment is a physical disinfection method that does not introduce chemicals or produce by-products, and is suitable for a wide range of water treatment applications, such as drinking water, swimming pool water, and industrial wastewater.
Comparison Of Three Sterilization Methods
| Features | Ozone | Sodium hypochlorite | Ultraviolet |
| Mechanism | Has strong oxidizing properties and kills microorganisms by oxidation. | By releasing hypochlorite ions, which have a bactericidal effect. | Uses ultraviolet light (UV-C) to destroy the nucleic acids of microorganisms, stopping them from reproducing and growing. |
| Chemical Addition | Adding ozone generator produced by an ozone generator. | Addition of chloride-containing sodium hypochlorite solution. | Uses only UV light. |
| By-products | Harmful by-products are usually not produced. | May produce chloride-containing by-products | Does not produce chemical by-products. |
| Sterilization effect | Strong oxidizing properties make it highly effective in killing bacteria, viruses and organisms. | Good bactericidal effect, but less effective in treating certain organics. | Kills microorganisms better, but has limited removal of organic matter from water. |
| Applicable water quality | Suitable for a wide range of water qualities, including sewage and drinking water. | Suitable for drinking water and swimming pool water, etc. | Suitable for drinking water, swimming pool water, water treatment plants, etc.. |
| Equipment complexity | Precise control of ozone concentration. | Reasonable amount of sodium hypochlorite is administered. | Relatively simple equipment, mainly including UV lamps and reactors. |
| Operating Costs | Ozone generator and oxygen supply costs need to be considered. | Regular monitoring and control of sodium hypochlorite delivery. | Lower |
How to sterilize with UV light?
The use of UV disinfection for water treatment wastewater typically involves the following major steps:
Intake: The introduction of wastewater from the source into the treatment system. This can be raw sewage from a wastewater treatment plant, industrial process, or other raw sweage.
Pre-treatment: Some pre-treatment steps may be required before the wastewater enters the UV disinfection system. Wastewater may contain large solids such as leaves, paper, etc. These large particulate materials are screened out of the water during the initial screening stage using grids, wastewater screen, or other equipment.
Sedimentation: Wastewater enters a sedimentation tank that allows larger solid particles to settle in the water. This settled material forms sludge, which can be further clarifiers of as water treatment. To ensure the clarity and cleanliness of the wastewater and to allow UV light to penetrate the water microorganisms more effectively.
Biological treatment: After initial treatment, the wastewater may still contain organic substances and pollutants. In the biological treatment stage, activated sludge is utilized to degrade these organic substances into simpler compounds, reducing the organic load in the water. Alternatively, an air flotation system using an aeration tank is used to degrade the organisms.
Chemical treatment: the aim is to remove specific yarns such as phosphorus, nitrogen, and heavy metals from the wastewater. This is usually achieved by chemical treatment with wastewater chemicals.
UV disinfection shot: Treated water is passed through a UV disinfection system, which consists of a UV lamp and a reactor. The UV lamps produce UV-C rays that irradiate the wastewater, destroying the nucleic acids of microorganisms in the water and preventing them from reproducing and growing.
Summary
UV disinfection is an efficient, environmentally friendly water treatment method that does not introduce chemicals and is suitable for disinfecting wastewater and meeting discharge standards. Reasonable use of UV disinfection can improve the standard of water quality treatment.
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