You might want to find out vendors who have installed biofilters in cold climate and talk to their customers. Electricity, steam, natural gas, whatever is available. If there is some heat that can be recovered somewhere an used to heat the airstream, that's even better. I personally do not classify biofilters by their genealogy. The biofilter generation is not an indication on how good it is, I take it as a vendor marketing operation.
Performance depends who designs the biofilter, and who operates it.
We were originally thinking of a water scrubber to humidify air to a compost biofilter. You are on the right track, it depends on you raw air temperature and relative humidity, the temperature and loading of you biofilter, and finally the size of your scrubber. I understand the scrubber are existing, they may or may not be appropriate. Maybe additional sprinklers on top of the bed might be sufficient. You are on the right track considering biofilters.