Over the last two years, Wageningen UR Greenhouse Horticulture has conducted research into purification equipment to remove crop protection agents from discharge water. In anticipation of the Dutch and European crop protection and water policy for the next ten years, the Platform for Sustainable Greenhouse Horticulture (Platform Duurzame Glastuinbouw) has formulated the aim of practically zero emissions in 2027. There is political pressure to achieve this objective even sooner. This is why a suitable purification method is urgently required. This can also play an important role in the authorization of new crop protection agents or the re-approval of agents already in use.
The crucial question is what this policy is going to mean in concrete terms for an individual greenhouse horticulture company. Water specialist Nico Enthoven from Priva has a few more questions about this. "Will every company eventually need to have a purification system or is this only required for the use of specific agents? And can growers still use every agent in the future? These are practical questions which require practical answers. Right now, this development appears to be a threat, but with timely anticipation, it can also present opportunities, certainly in the longer term", he says with conviction.
From threat to opportunity
In order to make a correct assessment of the feasibility and affordability of emission reduction measures and sustainable production methods, he believes that it is not only important to examine the costs, but to have insight into the benefits also. This relates to the benefits of making cost savings at a company level, and also to the advantages in the chain and cost savings for society. "Priva's Vialux HD/UV oxidation already allows growers to achieve a reduction of emission of 80 per cent."
It is no surprise that this system did very well in the tests conducted by Wageningen UR. The HD/UV oxidation module is a new component that can be used on the Vialux HD/UV disinfection unit. Disinfecting with UV light with the addition of hydrogen peroxide provides an effective and thorough disinfection of water. This method makes drain water reusable to a greater extent, which results in substantial savings.
Nico Enthoven explains the principle succinctly. "Disinfecting with HD/UV and hydrogen peroxide (H2O2) reinforce each other during the disinfection process. The ultraviolet (UV-C) light kills bacteria and viruses, while the oxidising action of the hydrogen peroxide also eliminates growth inhibitors and crop protection agents in the drain water, basin water or surface water. It's good for the plant, less water is discharged, it's better for the environment; it's cost-effective and also production and quality may be better", he says in summary.
Naturally, Priva has conducted various practical tests with HD/UV-oxidation. The tests, in different cultures, demonstrated that water can be recirculated longer and the crops were healthier. The follow-up project is currently investigating the optimal dosage of HD/UV and H2O2 concentration for removal of crop protection agents.
Nico Enthoven emphasises that there are many advantages to the Priva HD/UV oxidation module. "You can dose very small amounts accurately and equably. The dosing principle is such that air bubbles formed (possibly blocking dosing lines) are sucked away immediately. Also the amount dosed can be regulated easily: the module is fully integrated into existing Priva process computers."
With the oxidation module for the Vialux HD/UV, Priva provides a total solution in the field of accurate fertilization and recirculation. "As a result of the accuracy, the drain water is easier to recirculate", said Priva's water specialist. "This is made possible by the Priva fertilizer dosing systems (Nutri-Line) and the flexible control using Priva Connext/Intégro." The Vialux HD/UV disinfector facilitates safe recirculation. The disinfection dose is monitored continuously. An optimal capacity is guaranteed for (variable) water quality.
Vialux HD/UV provides greater security. More recirculation is possible, which leads to fewer discharges and that means lower costs. The discharged water can be treated using the same equipment and thus contain up to 80 per cent less agents.
On the right road with PrivaNico Enthoven endorses the need for greenhouse horticulturists to seriously consider the purification of discharges. "After all, 2016 is just around the corner." He does not, however, support the assumptions that this leads to extremely high costs for growers. "As mentioned, Priva has an efficient method available, using a small modification to the existing equipment: hydrogen peroxide dosing. This gives growers the opportunity to save costs and reduce substantially emissions into the environment and in doing so to comply with more stringent regulations in 2016. The availability of a good purification method is of great importance for retaining a necessary package of crop protection agents."
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