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UV Dose & Disinfection Calculator

Calculate UV lamp requirements, power consumption, contact time, and estimated log reduction for wastewater and potable water disinfection. Accounts for UVT, fouling, lamp efficiency, and redundancy.

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UV Dose & Disinfection Calculator

Enter your process parameters below to calculate design values. All calculations follow industry-standard methodologies.

m³/day
mJ/cm² (default from organism above)
% at 254nm (typical 65-95% for WWTP, >95% for potable)
Watts per lamp (typical 150-500W medium pressure, 30-40W low pressure)
% (typical 25-35% medium pressure, 30-40% low pressure amalgam)
% output reduction (typical 10-20% for wastewater)
% (typical 1+1 = 100% standby, 2+1 = 50%)

UV Disinfection Standards

UV disinfection for wastewater must meet regulatory requirements. In the US, the EPA UV Guidance Manual specifies dose requirements. In Europe, the Bathing Water Directive and Urban Wastewater Treatment Directive set microbiological standards. Common targets include 100 mJ/cm² for E. coli reduction, 400 mJ/cm² for Giardia, and up to 10,000 mJ/cm² for Cryptosporidium inactivation. Biodosimetry testing with MS2 coliphage is the standard validation method.

  • US EPA UVDGM: 100 mJ/cm² for secondary effluent
  • California Title 22: validated with MS2 biodosimetry
  • German DVGW: 400 J/m² (40 mJ/cm²) for potable
  • EU UWWTD: E. coli < 1000 CFU/100mL

UVT and Water Quality

UV Transmittance (UVT) at 254nm is the most critical water quality parameter for UV system sizing. Typical UVT values: potable water >95%, secondary effluent 65-80%, filtered effluent 75-90%, nitrified effluent 60-75%, industrial wastewater 30-70%. Low UVT dramatically increases lamp requirements. Pre-treatment by filtration or coagulation can improve UVT. UV intensity sensors with automatic wiping compensate for fouling.

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