UV Dose for BWMS (rough empirical estimate)
Order-of-magnitude UV dose for a BWMS reactor as a function of lamp UV-C output, flow, and UV transmittance. Empirical fit only: actual BWMS dose-credit requires biodosimetry.
Formula, assumptions, and limits
This is a vendor-curve fit reduced to a closed form, NOT a derivation from first principles. The constants and together encode the unit conversion (W·s/h → energy per unit volume) and the typical reactor geometry (effective beam area / volume per metre of flow path) of representative gravity-flow medium-pressure UV BWMS. They are NOT physical constants and should not be relied on for an unfamiliar reactor.
The exponent reflects the empirical observation that effective dose falls off faster than linearly with declining UV transmittance: high-turbidity coastal water (UVT 30-40 %) cuts effective dose by 60-80 % vs clean ballast (UVT > 90 %). The 1.5 exponent is a fit to vendor curves, not a Beer-Lambert derivation.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Total lamp UV-C output (germicidal 254 nm) | W | BWMS lamp data sheet | |
| Treatment flow rate | m³/h | BWMS operating setpoint | |
| UV transmittance at 254 nm (percent) | % | UVT sensor / lab | |
| Empirical fit constant (≈ 10 for representative medium-pressure BWMS reactors) | - | vendor-curve fit |