Ultraviolet light is a part of electromagnetic waves, sewage disinfection with ultraviolet wavelengths of 200 ~ 310 (mainly 254) nm wave spectrum area.
The ultraviolet dose of sewage should be determined by test, can also be determined by reference to similar production and operation experience. No test data, can be determined in accordance with the following standards:
The secondary treatment of the effluent for the 15-22 mws/cm2;
Reclaimed water for the 24-30 mws/cm2.
Ultraviolet irradiation ditch design should meet the following requirements:
Irradiation ditch water flow uniformly, before and after the lamps before and after the canal length should not be less than 1m;
Water depth should meet the flooding requirements of the lamp.
Ultraviolet irradiation canal should not be less than two. When one is used, it is appropriate to set up beyond the canal.
Ultraviolet dose to inactivate some pathogens
Pathogens Ultraviolet dose (unit mWS/cm2)
90% 99% 99.9% 99.99%
Cryptosporidium <10 <19
Giardia <5
Vibrio cholerae 0.8 1.4 2.2 2.9
Shigella dysenteriae 0.5 1.2 2.0 3.0
Escherichia coli 1.5 2.8 4.1 5.6
Salmonella typhimurium 1.8-2.7 4.1-4.8 5.5-6.4 7.1-8.2
Shigella typhi 3.2 4.9 6.5 8.2
Salmonella enterocolitica Salmonella 5 7 9 10
Hepatitis virus 4.1 ~ 5.5 8.2 ~ 14 12 ~ 22 16 ~ 30
Poliovirus 4 ~ 6 8.7 ~ 14 14 ~ 23 21 ~ 30
Coxsackievirus B5 virus 6.9 14 22 30
Rotavirus SAII 7.1 ~ 9.1 15 ~ 19 23 ～26 31～36
Ultraviolet dosage for disinfection in some municipal sewage treatment plants
Plant name Water to be disinfected Ultraviolet dosage (mws/cm2) Built time (year)
Shanghai Changqiao Wastewater Treatment Plant A/A/O secondary effluent 21.4 2001
Shanghai Longhua Wastewater Treatment Plant A/O secondary effluent 21.6 2002
Wuxi Xincheng Wastewater Treatment Plant Secondary Effluent 17.6 2002
Shenzhen Dazhong District Wastewater Treatment Plant (Phase I) Secondary Effluent 18.6 2003
Suzhou New District No.2 Wastewater Treatment Plant Secondary Effluent 17.6 2003
Shanghai Minhang Wastewater Treatment Plant A/O Secondary Effluent 15.0 1999
Shanghai Minhang Wastewater Treatment Plant