Phosphine circulation in stored wheat in a thermosyphoning silo

Research output: Other contribution to conferenceAbstractpeer-review

Abstract

Stored grain requires fumigation to prevent damage from pests, such as insects. A 50 t thermosyphoning silo was outfitted with gas sampling lines at three depths in the grain body and also in the silo headspace. Fifty tonnes of wheat were loaded and allowed to settle for 1 wk. The silo was sealed, pressure tested, and fumigated with aluminum phosphide tablets using an external, ground-level, fumigation chamber attached to the base of the thermosyphoning pipe. Phosphine concentrations were measured each morning using handheld meters. Once the minimum fumigation standards of 200 ppm for 10 d or 300 ppm for 7 d were met, the silo was vented using an integrated blower fan. This process was repeated three times in each calendar season, for a total of 12 fumigation cycles. Results showed that phosphine concentrations rapidly increased and tended to be slightly greater in the lower level of grain compared to other levels, due to a density of phosphine greater than air. Maximum concentrations in a cycle ranged from 400-800 ppm across the 12 fumigation cycles, and phosphine concentration standards were reached and exceeded in all 12 fumigation cycles throughout the year in 12.5 to 22 d, regardless of weather conditions. The silo remained sealed in the final fumigation cycle after the minimum fumigation standards were met, to characterize the sealing ability of the silo. Results showed the phosphine concentration did not fall below 200 ppm until 106 d after fumigation. These results demonstrate the ability of thermosyphoning to rapidly circulate fumigant throughout the grain body and maintain fumigant concentration for periods well in excess of Australian fumigation standards. The thermosyphoning silo also reduced the risk of explosion and improved operator safety by allowing ground-level fumigation to occur.
Original languageEnglish
Pages61
Number of pages1
Publication statusPublished - 2024
Event12th International Conference on Controlled Atmosphere and Fumigation in Stored Products: CAF2024 - Winnipeg, Canada
Duration: 18 Aug 202423 Aug 2024
https://umanitoba.ca/research/caf2024 (Conference website)

Conference

Conference12th International Conference on Controlled Atmosphere and Fumigation in Stored Products
Country/TerritoryCanada
CityWinnipeg
Period18/08/2423/08/24
OtherComplete proceedings attached to PID 532578096

The International Conference on Controlled Atmosphere and Fumigation in Stored Products (CAF) occurs every four years in different locations around the world. They provide a major international forum for reporting advances in research and development on gaseous treatments for the preservation of stored commodities such as cereal grains, legumes, root crops, dried fruits, nuts, vegetables and agricultural products including bulbs and flowers.
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