Water decontamination

Decontamination of drainage water is an important operational process in every greenhouse

Decontamination of drainage water is an important operational process in every greenhouse. Since the irrigation water is fundamental to crop growth, it must be of a high quality.

Decontamination must provide sufficient protection against the spread of harmful microorganisms such as bacteria, viruses, moulds and nematodes in the recirculation of drainage water since many such microorganisms can cause serious plant diseases with potentially disastrous financial consequences.

There are several different methods of decontaminating water in a recirculating crop cultivation system:

• UV radiation
  The discharge water and/or feed water is decontaminated by exposing it to UV radiation.
• Heating
  The water is heated to kill off harmful microorganisms without damaging fertilisers.
• Hydrogen peroxide
  This oxidises all the organic material present in the water. It is a fast and effective method requiring limited investment.
• Reverse osmosis (membrane filtration)
  In this water purification process, the water is pumped at high pressure through a membrane against the natural osmosis flow direction. This results in the loss of fertilisers.
• ECA
  Electro-chemical activation (ECA) or electrolysis entails an electrical current being passed through a liquid. In the ECA unit, softened tap water containing dissolved potassium chloride is activated by electrolysis to produce an ECA solution.

• Ozonisation
  This oxidises all the organic material present in the water. It is a suitable method for keeping reservoirs clean.
• Copper
  Bacteria and moulds cannot survive or multiply if copper is added to the water. This is also a suitable method for keeping reservoirs clean. However, one disadvantage is the increased copper content in the feed solution.
• Chlorine dioxide
  This oxidises and destroys all the organic material present in the water and the water pipes. Chlorine dioxide does not come into contact with the plants because the gas escapes as soon as it leaves the sprayer.
• Sodium hypochlorite
  This oxidises and destroys all the organic material present in the water and the water pipes. Sodium hypochlorite is dissolved in the irrigation water. It comes into contact with the plants in order to combat the undesirable microorganisms that are on them.

The preferred decontamination method varies from one company to another. Factors which affect the decision include:

• Purpose of decontamination
• Effectiveness
• Capacity
• Investment costs
• User costs
• Integration in the crop cultivation system.

Our specialists would be happy to advise on the right water decontamination system for you.