ISHS Acta Horticulturae 548: International Symposium on Growing Media and Hydroponics
DISINFECTION OF RECIRCULATION WATER FROM CLOSED CULTIVATION SYSTEMS BY HEAT TREATMENT |
| Authors: | W.T. Runia, J.J. Amsing |
| Abstract:
In the Netherlands crops are grown nowadays mostly in closed cultivation systems. Pollution of the ground and surface water with nutrients and pesticides have led to a law which prohibit growers to let the excess nutrient solution run off. Reuse of excess nutrient solution however implies a risk of dispersal of plant pathogens. Disinfection of excess nutrient solution before reuse can eliminate this risk. Currently water disinfection by heat treatment, ultra-violet radiation, ozonation, slow sand filtration or lava filtration is applied on approximately 1800 nurseries. Up to now the advice for heat treatment is to treat the water for at least 30 seconds at 95oC. An extra boiler is required to realize this temperature. Moreover most beneficial organisms can’t survive this temperature. With a commercial heating installation several exposure times and temperatures were tested for efficacy against Fusarium and tomato mosaic virus. Both pathogens were eliminated at 85oC during 3 minutes. In a laboratory set-up adults and juveniles of the burrowing nematode Radopholus similis were killed at 48, 50 and 52.5oC during 5 and 2 minutes and 30 seconds, respectively. | |
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