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Engalls Nursery – Dam water UV disinfection for irrigation of citrus trees


Engalls Nursery, Dural, NSW


Dam water treatment for citrus tree irrigation



Engalls Nursery are specialist growers of citrus. Since 1976 they have been growing citrus and fruit trees at their 4 hectare nursery in Dural, NSW. Their crop is irrigated using dam water stored at the lowest point of the nursery.

Following recommendations by the Nursery and Garden Industry (NGIA), and in order to achieve NGIA certification, Engalls explored their water treatment options. UV-Guard were contacted after UV disinfection was the preferred choice. Key to the decision of the nursery owner was the ability of a UV disinfection system to provide treatment inline in comparison to alternative chemical solutions that required large storage tanks.

A UV-Guard process engineer worked closely with the nursery owner and the NGIA to design a solution that incorporated the correct level of treatment required. Water samples were taken by UV-Guard and the UV Transmittance (UVT) was tested in the UV-Guard laboratory. UV dose requirements were established after considering the pathogens that needed to be controlled. Phytophthora and Pythium were the species highlighted as a risk to the crop at the site.



  • Media filtered dam water treatment
  • UVT of 55%
  • Peak flow rate of 25 m3/hr
  • Required UV dose of 100 mJ/cm2
  • Auto wiping quartz system
  • UV intensity monitoring


  • UVG X4-440 AW

The WaterMark certified UVG X4-440 AW system was selected after completing UV dose calculations with the water quality and UV dose requirement figures established in the pre-design. It meets and exceeds the requirements set out by both the NGIA and the nursery owner and will provide a UV dose of 100 mJ/cm2 at the end of lamp life for a peak flow rate of 27 m3/hr where the UVT is 55%.

spray-machine1The skid mounted UVG X4-440 AW system consists of four 450W low pressure UV lamps. Incorporated into the design is a quartz auto wiping system that is activated by UV intensity values measured by a UV intensity sensor and monitor. When the UV intensity drops to a pre-defined value, the wiping system will initiate and clean the quartz, resulting in the design UV dose being maintained.

The system is controlled by an existing irrigation controller at the nursery. This means that the system is turned on and off only when required. This is a feature that was recommended by UV-Guard in order to prolong UV lamp life whilst also reducing power consumption.

If you have horticulture water treatment enquiry, contact a UV Guard process engineer today.