MHTV is connected to the vent line leaving your boats toilet waste holding tank. Then, before any air can travel from your holding tank to the vent it must first pass through the filter.
MHTV works by passing the vent line air through a filter comprised of activated carbon pellets before it escapes. Activated carbon is a special type of highly porous carbon. The effective surface area of just one gram of Alpha-Pure carbon is over 500 square meters!
The actual toilet odor that comes from your holding tank is made up of tiny particles of various types. Since the holes in the activated carbon pellets inside of the MHTV are so small, the odor particles are trapped as they pass through the filter.