Evaluating the efficacy of a screen humidity cell in filtering pathogens and other particulates out of air in potato stores


Cold storage (below 4°C) can increase the storage life of the crop by reducing the metabolism of the tuber and slowing or preventing sprouting. At such low temperature, the cool air has a drying effect, causing water loss from the potato. To counteract the drying effect systems that increase the humidity of storage atmospheres can be useful. Historically three types of humidification systems had been available: high-pressure nozzles, centrifugal spinning disks and evaporative media. However, there had been a decline in use of humidifiers that produce mists, and increased interest in evaporative media humidifiers. They pass air through a water laden membrane,  producing air saturated with water vapour. The process potentially provides a filtering effect and the purpose of this work was to examine to what extent an evaporative media humidifier filtered out fungal spores and bacteria from air in potato stores.

The work involved a comparison of the Munters HM2 4000 and an ultrasonic nozzle humidifier and the number of fungi and bacteria in store air were determined by counting the number of colonies that grew on dishes containing a growth medium.

The amount of fungal contamination in the recirculating air was the same irrespective of whether the Munters HM2 4000 or an ultrasonic nozzle humidifier had been in operation. The amount of bacterial contamination in the recirculating air was much higher in the store where an ultrasonic nozzle humdifer had been in operation compared with a store with the Munters HM2 4000. It is likely that the atomised water itself was the source of the contamination.

Project code:
01 June 2006 - 31 December 2006
Project leader:
Jeff Peters


R284_Final Report_2006

About this project

To assess any effects of humidifier cells on levels of pathogens, development of disease, and other particulates in air in potato stores