1. Comparison of Disinfection Targets
UV disinfection inactivates bacteria by eliminating their reproductive capacity, thus effectively killing most viruses and bacteria.
Sodium hypochlorite disinfection is a type of chlorination disinfection, and its biggest problem is its ineffectiveness against certain viruses and spores.
2. Comparison of Byproducts/Environmental Impact
Because UV disinfection technology does not add any chemical agents, it does not cause secondary pollution to water bodies or the surrounding environment, does not change any components in the water, and has a positive impact on protecting the health of workers.
Sodium hypochlorite disinfection produces disinfection byproducts such as trichloroacetic acid, diaminoacetic acid, and chloroform. Animal experiments have shown that many chlorination byproducts are mutagenic and/or carcinogenic.
3. Comparison of Effects on Subsequent Disinfection
UV disinfection does not provide residual disinfection capacity. After the treated water leaves the reactor, some microorganisms killed by UV light can repair damaged DNA molecules through photoreactivation mechanisms, allowing bacteria to regenerate.
Liquid chlorine, like sodium hypochlorite, is a chlorination disinfectant. After disinfection, a certain amount of residual chlorine remains in the effluent, indicating residual disinfection capacity.
4. Comparison of Water Quality Requirements
UV disinfection is not suitable for water with low UV transmittance (slurry suspended solids (SS) above 30 mg/L). It not only increases energy consumption but also results in poor disinfection effectiveness.
For secondary treated wastewater and reclaimed water, where UV transmittance is generally 40-80%, UV disinfection is a good choice.
Sodium hypochlorite disinfection has low water quality requirements and generally meets the standards for wastewater treatment effluent.
5. Comparison of Treatment Contact Time
Generally, liquid chlorine disinfection contact time is around 10-30 minutes, sodium hypochlorite disinfection time is slightly shorter, and UV disinfection time is the shortest.
6. Comparison of Operation and Management
UV disinfection is powered by electricity, making daily operation convenient. UV lamps and quartz sleeves only need periodic replacement and cleaning.
Sodium hypochlorite disinfectant should not be stored for long periods; generally, only a few days' worth is needed to maintain the disinfection effect.
7. Comparison of Operating Costs per Ton of Water
UV disinfection costs approximately RMB 0.020/ton (including lamp replacement costs), while sodium hypochlorite costs approximately RMB 0.034/ton. (Based on actual data from two different wastewater treatment plants)
It should be noted that disinfection costs and effectiveness are easily affected by factors such as the dosage of disinfectant (or UV dose), contact time, and the quality and quantity of influent. Therefore, the above cost data are only partially relevant for reference.
