Our work

Daylight driven water treatment for greenhouses

TNO is developing photocatalytic oxidation (PCO) as a possible new, sustainable water treatment and purification method for greenhouse horticulture. In PCO processes, inert, non-toxic, inexpensive catalysts (such as TiO2) are used in combination with oxygen (from air), water, and UV-A light to generate OH radicals. The radicals have a strong oxidative effect and can purify water and break down pesticides.

Photocatalytic oxidation (PCO) uses inexpensive, non-toxic catalysts, and UV-A light to create radicals. These radicals can kill germs and break down organic substances. TNO research, in collaboration with PT, Priva TTO, and WUR, has demonstrated that daylight-driven PCO can break down more than 90% of pesticides. Effectiveness and costs are competitive with conventional techniques. PCO also has a wide range of applications in the greenhouse and therefore opens the way for new additional sterilization/decomposition concepts. Use of artificial light reduces the required surface areas.


Competitive relative to conventional techniques:

  • Immobilized TiO2 in combination with UV-A for treatment of discharge water
  • PCO for removal of impurities from discharge water with upstream TOC removal

Promising concepts:

  • Integration of TiO2 in concrete growing floors
  • Use of immobilized TiO2 as temporarily deployable additional aid for breakdown of pesticides and/or sterilization (e.g. as roll-out film or additive)
  • Use of optical fibres (light at any desired location) and innovative reactor concepts (more compact systems)

Follow up

  • Continued development + evaluation of promising concepts
  • Selection of most promising PCO concept
  • Demonstration of PCO on location

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