I would be grateful for any advice on how to clean up small amounts of zinc powder that includes a very small percentage of mercury. Currently we use vacuum cleaners with an activated carbon filter however our supplier will no longer supply us with filters due to "a change in legislation which means it is no longer legally compliant to use this method of cleaning up mercury in the EU."The substance is in powder form although negligible amounts of mercury vapour can be detected when using this type of equipment. Employees are subject to regular biological monitoring with results well below guidance values. The spillages occur at quality control stations or when maintenance is carried out on the machinery and involve small amounts of powder/dust.

It's probably only the older laboratory scientists like myself who remember the universal use of mercury in glass thermometers, and especially those which seems to break as soon as you looked at them. Zinc dust was, and still is, the easy approach to spill management, plus occasional clearing of sink traps and U-bends. There are now ready to use spill kits based largely on the same zinc dust. We always swept treated spillages into a pot using a stiff 1" paintbrush, finishing off with a piece of damp paper towel to remove and zinc dust residues. The game becomes more difficult if you have teach benches designed and manufactured in the pre-war years, but now the design and construction standards should eliminate all of the nooks and crannies into which mercury will find its way. Where those little cracks and gaps become contaminated, a simple hand held vac pump , perhaps operating from a Venturi on a nearby tap will suffice. A simple trap bottle can be cobbled up, or you might purchase one if you don't subscribe to the Blue Peter generation. Works a treat.

Myself, I would go for this method, outlined by Ian: "We always swept treated spillages into a pot using a stiff 1" paintbrush, finishing off with a piece of damp paper towel to remove any zinc dust residues." Or even just use damp paper towel if the spillages really are small. Vacuuming does not remove all dust anyway, so has only partial effectiveness.

We also used the same procedure as outlined by Ian. The zinc mercury “mix” was then labelled and taken away by our special waste contractor. We also used this procedure outside the lab environment as on one occasion, an overseas visitor broke a very old mercury thermometer in a sink in student accommodation. We never did discover what he was doing as he did not report it before leaving. Fortunately the broken glass was spotted by our domestic staff and reported.

Why do you want to pfaff around with a filter when you can use a trap? If you have a suitably low vacuum line, or a water Venturi connected by a simple rubber hose to first a trap bottle, possibly 2 traps in sequence if you want to be certain, and finally a probe or sucker of suitable bore, it is likely to do the trick for you. I used to use one fashioned from glass tube and glass bottles but use whatever you have to hand. Fill traps with water to an appropriate level, and make sure you keep them upright with the inlet and outlet tubes at the appropriated inferential levels. I'm sure you could knock it up for pennies and quickly convince yourself how effective it will be. Bring back Auntie Val, toilet roll tubes and sticky backed plastic. Life was so much easier then