UV-Oxidation Technology for Disinfection of Recirculation Water in Protected Cultivation

Recirculation water of agricultural or horticultural crops may be infected with root pathogens.
Disinfestation of the water before re-use eliminates the risk of dispersal of pathogens.
Options for water treatment are heat treatment, ultraviolet irradiation (UV), ozonation or slow filtration.
With the objective to reduce the energy input in comparison with UV-irradiation at an equal efficacy, UV-oxidation technology was tested against Fusarium oxysporum. The optimum concentration of hydrogen peroxide (H₂O₂) proved to be 1 mmol L^-1. After injection of 1 mmol L^-1 of H₂O₂ in recirculation water with a UV transmission value (T₁₀) of 20%, just before passage along the UV-lamp, the D₁₀ value (90% reduction) was 18 mJ cm^-2 at a pH of 6 and 13 mJ cm^-2 when the pH was 4. Without application of H₂O₂ the required UV-C doses under the same conditions where 20 mJ cm^-2 and 18 mJ cm^-2, respectively.
When the T10 of the recirculation water with pH 4 was 10%, the D₁₀ value amounted to a UV-C dose of 51 mJ cm^-2 when 1 mmol L^-1 of H₂O₂ was applied and to 65 mJ cm^-2 without H₂O₂. In this study UV-oxidation technology, applied for the treatment of recirculation water, reduced the energy input with 10% to 28% in comparison with solely UV-irradiation.

International Symposium on Growing Media and Hydroponics

W.T. Runia, S. Boonstra

D₁₀, Fe-DTPA, Fe-EDDHA, Fusarium oxysporum, hydrogen peroxide, hydroxyl radicals, pH, rockwool, T₁₀, UV/H₂O₂

https://doi.org/10.17660/ActaHortic.2004.644.73