Fruit grading water easily purified with active carbon filter

Fruit grading water so clean that it may be discharged into the sewage system. This is possible with the system developed by Applied Plant Research (PPO). Legal recognition is the next step.

It is a recurring problem: during the grading period a fruit grower needs to dispose of some 5 to 10 cubic metres of grading water each week. Discharging into the sewage system or into a ditch is no option because the water is too polluted with pesticides residues from the fruits. Discharging into the orchard is possible but this results in the orchard getting too wet.

Filter installation cleans the water

The scientists of PPO have developed a simple method suitable for use by any fruit grader. The installation consists of a plate separator, an ozone installation and an active carbon filter. The plate separator removes the largest possible part of the sludge and organic matter from the water. This is followed by decomposition of the crop protection products in the ozone installation. Purification in the ozone units happens in separate flows. The fruit does not get into direct contact with the ozone water. During the grading period the plate separator and the ozone installation are running continuously. The carbon filter is only used during final discharge and removes the last residues of the crop protection products from the grading water.

The end of the grading tray is fitted with a unit through which the grading water is passing continuously. This is an active carbon filter that filters all organic matter, such as slurry, from the water. And dissolved pesticides and organic matter disappear by oxidation in the ozone installation.

With this method the fruit grader only needs to replace the grading water once every 4 to 8 weeks. And this water is so clean that it could be discharged into the sewage system.

The active carbon filter itself needs to be replaced about once every two years.

The system works to complete satisfaction at two growers’ sites but is not yet legally permitted. The Ministry of Infrastructure and Environment and Waterboard Authorities are still deliberating how it can be safeguarded that fruit growers are using the method correctly. After that, the Ministry can include the system as permitted method in the Activities Decree.