IMPORTANT NOTE:

There is a design flaw in this project, the actual UV leds LZ1-00UA00 are 3W not 5W like in that marketing bullsh|t from their datasheet. 5W is only permitted in short pulses.
I am a bit upset because mine burned out after a year of use since the current regulator was set for this 5W, and they are pretty expensive.

To solve the issue please use 1.8Ohm resistor ( 2x3.6Ohm in parallel )  in the output of the LM317, regulating the current to 700mA.

And use adequate cooling for the whole stuff, these leds are pretty sensitive to high temperature.
I made a new PCB board for them from a 0.3mm thick laminate and glued it to the heatsink, thus having minimum rosin thickness between the copper + led and the heatsink, better dissipating the heat.