Your biological filter requires these major considerations to function efficiently each as important as the other:

The filter in an HRV requires periodic cleaning and should be changed twice a year.

While GAC filters usually cost less than aeration systems, filters can collect radioactivity and may require a special method of disposal.

A quotient filter requires 10-25% more space than a comparable Bloom filter but is faster because each access requires evaluating only a single hash function.

"The precision their filters would require seems greater than the laws of atomistics would allow."

Active filters are implemented using a combination of passive and active (amplifying) components, and require an outside power source.

One example is ADSL applications, where filters typically require 20 bits of accuracy.

This filter requires large-value high-current inductors, however, which are bulky and expensive.

Other filters like cyclonic filters require the airflow to be high on a permanent basis, or else the performance of the filter drops.

But those filters are often 5 to 10 times as expensive and require more powerful air-circulation systems, and so are not used in many buildings.