Last week, a collective water treatment plant for greenhouse horticulture was opened in Hoek van Holland, the Netherlands. During the official opening, the greenhouse horticulture sector received compliments for taking steps in the right direction.
95% purification efficiency
There was a meeting of all partners involved in the realization of a PACAS installation. The installation will ensure that more than 300 horticulturists, representing more than 1,000 hectares, have their water centrally purified of crop protection agents. For example, gardeners are still joining after mergers. The sector cooperated with the Delfland Water Board, three municipalities, and the province of South Holland, among others.
Bart van Meurs, the project leader, spoke on behalf of the growers. He discussed how the first steps were taken as early as 2013,in response to legislation demanding 95% purification efficiency for crop protection products.
The initial business strategy was conceived in 2016, with a key focus on securing sufficient irrigation water to facilitate the construction of a plant. This was crucial because the water from the greenhouse, which is not separately identified, merges with a collective pool of wastewater from residential areas and various commercial operations.
Bart van Meurs highlighted figures in his presentation
25% horticultural water
Ultimately, 25% of 'horticultural water' arrives at the Hoek van Holland sewage treatment plant. "For Dutch standards, that's a lot" Bart indicated. Thanks to this initiative, the remaining 75% is also purified of medicine residues, among other things.
At the wastewater treatment plant on the premises of Hoogheemraadschap van Delfland in Hoek van Holland, an extra treatment step has been created so that crop protection agents are removed and the wastewater becomes even cleaner. An additional advantage is that medicine residues are also filtered out of the water. It is a big step towards cleaner surface water.
Werner Krijger, project manager on behalf of Hoogheemraadschap van Delfland
Pressure pipe
Bart has been involved in the project since 2019. In 2020, Waterzuiveringscoöperatie Westland (Water Purification Cooperative Westland) was set up. This includes growers of various kinds. The more growers get involved, the more beneficial it is, including financially.
A significant hurdle for the project, as highlighted in Werner Krijger's presentation, was the unexpected implementation of a much stricter bromate standard in 2021. Until that point, the project had been adhering to a Swiss standard, as Werner pointed out. However, the new regulation is 50 times more stringent. This change has made the use of ozone for purification unfeasible. Consequently, the project is revisiting the use of activated charcoal for purification. This method involves using powdered charcoal, which aids the bacteria in 'eating' the wastewater clean, effectively removing pesticides and medicinal residues and resulting in cleaner treated wastewater.
The project officially opened on 27 November, yet it remains unfinished. A crucial component still under development is a pressure pipeline intended to transport water from growers in De Lier to Hoek van Holland. This pipeline is expected to be operational by 2027. However, Bart emphasized that growers are not simply waiting idly. They have proactively implemented nine measures to enhance water quality.
Janwillem de Jong on behalf of Mobilis Croonwolter & Dros
Compliments
After a presentation by Janwillem de Jong on behalf of Mobilis Croonwolter & Dros, the group visits a sewage treatment plant with two PACAS plants. This ensures that purification can always continue, even if one of the two plants needs maintenance.
South Holland deputy Arne Weverling, Westland municipality alderman Michiel Ferwerda, board member of the Water Purification Cooperative Martin Boers, and high water board member Robert Tieman all spoke briefly just before the official opening. They are positive and state that the sector is helping the entire region with this initiative. Thanks to the PACAS plant, the Hoek van Holland treatment plant is also well on its way to meeting new stringent European treatment standards.
Arne Weverling, Michiel Ferwerda, Martin Boers, and Robert Tieman
Growers pay
The growers affiliated with Waterzuiveringscoöperatie Westland will pay the costs of this collective purification, supplemented by subsidies from the Westland municipality, among others. Discussions are still ongoing with the Ministry of Infrastructure & Watermanagement, and the Province about a possible subsidy contribution.
Jacco Vooijs, chairman of Waterzuiveringscoöperatie Westland: "Treating waste water is not an everyday task for an entrepreneur. We are proud of the realization of the joint PACAS installation together with Delfland, but also of the fact that we managed to unite so many horticulturists in this collective."
Alternative to collective
There are no similar initiatives in the Netherlands. Guus Meis, Policy Specialist Water & Environment at Glastuinbouw Nederland, does point to the Bommelerwaard, where the greenhouse horticulture sector also purifies collectively, but on a smaller scale, and in a different way. The wastewater from the greenhouses enters here separately from regular wastewater. That makes it different. There are no places in the Netherlands where the percentage of wastewater from greenhouse horticulture at a sewage treatment plant is high enough to make an initiative from the sector itself profitable.
In the Westland/Delfland region, not all growers are connected. That doesn't mean they don't have to comply with the treatment rules themselves, or don't take steps themselves. Guus explains that there is a list of purification techniques from which growers can choose individually. This is the BZG list (in Duch).
The Collective Purification was designed by Sweco,Mobilis Croon Wolter & Dros, RWB, and ABB. Construction was carried out by Mobilis Croon Wolter & Dros with RWB as subcontractor.
