I wouldn't bother
There are a few Youtube videos showing how effective these wands are. To kill bacteria on a Microscope slide the wand had to be in near contact with slide for more than a minute to be semi effective. For a 1cm x 3cm area (the maximum these wands can illuminate at near contact) 1 minute and so for a 2 metre long kitchen worktop it would take approx. 60 hours incrementally moving the wand to get the same results. Other videos showing much more powerful UVc lamps being used to expose Petrie dishes after which the remaining bacteria were incubated for 24 hours indicated that a much longer exposure was required. These latter UV lights were the type you wouldn't want to be in the same room with if illuminated.