3:45 PM - 4:00 PM
△ [15p-B7-9] Inactivation of Bacteria Using Discharge Plasma under Liquid Fertilizer in Hydroponic Culture System
Keywords:discharge plasma under water, bacteria inactivation, agriculture application
We developed a system using discharge plasma under water for inactivating bacteria in hydroponic culture system, and evaluated the performance of the developed apparatus in a greenhouse for the period of 5 months using tomato plants in hydroponic culture system. The plasma reactor consisted of a wire electrode which was placed in an insulating circular cylinder, and a grounded electrode on cylinder outside. The reactor was sunk under the liquid fertilizer and atmospheric air was injected into the cylinder using a gas pump. The air is released through the holes of cylinder. Holes are 0.5 mm in a diameter and 2 mm separation one another. Repetitive nanosecond pulses were applied to the wire electrode, using a magnetic pulse compression (MPC) pulsed power generator. The amount of dissolved ozone into 100 L solution after one minute plasma treatment was obtained to be approximately 1.34 mg. The performance of the developed system was also evaluated using hydroponics solution contaminated with Ralstonia solanacearum, plant pathogenic bacterium. The number of CFU of R. solanacearum in the solution was decreased from 107 to 102 CFU/mL for 100 minutes operation. The bacterial wilt disease was significantly suppressed by the plasma treatment, while, all seedlings in a positive control wilted and died by infection of R. solanacearum. Then, the stability of the developed system was examined in a greenhouse environment. As a result, the developed system worked for 5 months in stable. The all plant bodies grew and produced fruit bodies healthily without growth inhibition due to oxidative stress or infection.