Unfortunately, the conventional trickling filter
approach does not recycle nutrients in the wastewater
but merely transforms them into non-toxic
(H2O, NO3) or gaseous forms (CO2, N2) [2].
We studied the possibilities of combining
wastewater treatment in constructed wetlands
with the production of crop plants biomass. The
idea was to use the surface of trickling filters to
grow crop plants, to combine the processes of
nutrient transformation (mainly nitrification) and
nutrient recycling. The original concept was established
by aquaponic producers [3,4], which
achieved remarkable fish to plant production ratios
in market-scale production systems. For each kilogram
of fish produced in feedlot aquaculture, the
nutrients in the resulting wastewater allowed a