Aeration is provided both by forced negative air flow and agitation from the paddle, which passes through the compost about once a day. It takes 18 to 23 days to move the feedstock from one end of the vessel to the other. One large fan provides aeration for the bed with 13 different zones for control. The fan is sized such that all necessary aeration could be provided without movement of the paddle. At the end of the bed, the material is emptied onto the floor, then moved to the curing area where aeration is provided utilizing in-floor piping.
Air is forced upwards through the material by two fans.
Negative air pressure for the entire building is provided by six additional fans. This is due to a number of factors. First, source separated residential organic material generally has a higher amount of fiber in its organic stream. N ratios far lower than the residential stream, however that material isn't being composted yet. Third, Halifax has never included boxboard in its dry recyclables.