Activities

Tests were conducted in a nursery that produces potted plants. Pots were laid on top of a sand filtration trench which collected the nutrient solution draining from the pots. The spent nutrient solution was gathered, enriched and fed again to the plants. To test the reduction of disease-causing microbes, Fusarium oxysporum (a fungus attacking tissues that transport nutrients) was added to the system in a massive innoculation. Then the amount of Fusarium o. and other disease-causing microbes was measured in the nutrient solution, the drained solution before entering the filter, within the filter substrate (sand) and the solution coming out of the filter. (see "additional information" field below for more information on the results of the project)

Additional comments

The abstract is extracted from the following article:

Penafeta-Boldú FX; Trillas I; Viñas M; Guivernau M; Cáceres R; Marfá O. (2017) Effectiveness of a full-scale horizontal slow sand filter for controlling phytopathogens in recirculating hydroponics: From microbial isolation to full microbiome assessment. Science of the Total Environment 599-600, 780-788

Additional information

Results showed a significant reduction of fungi in the system, which is mainly attributable to their adhesion to sand surface. In the long term, the microbe populations growing in the sand of the filter play a more important role in the control of disease causing microbes.



The project found that the sand filter not only reduced disease risk in the hydroponic system but also collected rain water and helped to reduce water consumption. The sand filter is part of CLEANTECH water recycling system which also counts on a pond to purify water pollutants. Both the clean water and the biomass produced in the pond can be reused in the nursery, reducing operation costs.