LTO Groeiservice and Wageningen UR Greenhouse Horticulture organized an information afternoon at Olij Rozen in De Kwakel on Thursday 29 March within the context of the Greenhouse Horticulture Waterproof Substrate Culture project. Approximately 35 growers, suppliers and consultants were present. Researchers provided an explanation for the new results from the research and those present discussed the options for the practical scenario.
Dutch surface water must be OK ecologically and chemically by 2015 in accordance with the European Water Framework Directive. The standards for pesticides and fertilizers are exceeded far too often in Greenhouse horticulture areas because drain water (nutrient solution) is being discharged.
“The solution to the problem starts by analyzing why growers discharge. Next, you can implement measures,” says researcher Erik van Os of Wageningen UR Greenhouse Horticulture. Since the summer of 2010 he has been working on two large "Greenhouse Horticulture Waterproof" projects with a number of colleagues. The projects must provide knowledge about closed circuits in Greenhouse horticulture. One research programme focuses on soilless cultures and the other on soil-bound cultures.
Van Os discussed the results of the research for soilless cultivation and presentations were given of a few purification technologies during the thematic meeting at Olij Rozen. Wageningen UR Greenhouse Horticulture has developed a reliable biotest that can prove growth inhibition. It has also been shown that it is possible to prevent growth inhibition by treating water with advanced oxidation using H2O2/UV. Residue of pesticides in the water are broken down in a large measure with this treatment.
TNO, Bruine de Bruin and Hellebrekers Technieken presented a concept for water recovery. They discussed two innovative technologies for cleaning discharge water: membrane distillation and ultrafiltration with reversed osmosis. They have arrived at the conclusion that it is technically possible to remove pesticide residue from discharge water from literature research and a pilot at Olij Rozen.
Erik van Os believes that there are two bottlenecks when reducing the discharge drainwater: “Firstly, we have a grower's commonsense. Basing oneself on clean water is certainly safe for the cultivation. Secondly, the additional investment into new purification technologies is currently too high for growers.” The next step is, therefore, developing a balanced business.