Keeping Water Clean

NZ Hothouse, a leading New Zealand provider of fresh produce, has opted to use UV technology to disinfect water used for soilless plant cultivation in its greenhouses.

Located near Auckland on North Island, NZ, Hothouse consists of almost 50 acres of greenhouses on two sites growing tomatoes, peppers, and cucumbers for national and international distribution.

The source of the water used for irrigation is a combination of rain water and borehole water that is stored in large outdoor holding ponds. The main microbial challenge in the water includes fungi such as Pythium, Phytophthora, and Fusarium, bacteria such as Clavibacter, and viruses such as tomato mosaic virus.

No conventional microbiological checks are carried out, but NZ Hothouse uses what it calls “bait tests” with very young plants to see if they fall victim to any of these waterborne pathogens.
To combat these pathogens, the company has installed two Aquionics PMD200 medium pressure systems, one for each site, treating up to 18,000 gallons of water per hour. UV treatment is said to be ideal for this application as it is a clean technology that introduces no chemicals or unwanted disinfection by-products into the water and does not alter the water’s pH.

The UV systems feature an automatic wiper which prevents the build-up of deposits on the quartz tube, ensuring optimum UV dose at all times.

For more information, contact Aquionics Inc. at 800-925-0440; [email protected]; www.aquionics.com