C.R.O.P. is a concept that combines the utilization of solid and liquid organic waste with soilless plant cultivation. The core of the C.R.O.P. system is a microbial trickling filter, which is able to degrade organic matter into inorganic compounds digestible by plants.
C.R.O.P. systems are envisioned for space and terrestrial applications.
The C.R.O.P. Filter
Imitating Soil. Passing through the soil, dirty water gets cleaned. When it reaches the ground-water reserves, it has achieved drinking water quality. Organic matter falls to the ground where it gradually disintegrates and is finally turned into inorganic compounds digestible by plants. These cleaning actions are accomplished by microorganisms, which form trophic networks underground. In the soil, these processes advance slowly. Moreover, regarding life support in space, soil is an unwieldy factor. Thus, in the C.R.O.P. system biofilters take over and accelerate the function of the soil. The growth of a multispecies biofilm composed of soil microorganisms is implemented by inoculation of porous lava particles with dried garden soil, then acting as substrate. The rough surface imitates the varying conditions in the ground providing separate habitats for a great variety of microorganisms.
Flexibility. Containing a community of soil microorganisms similar to those found in nature makes the C.R.O.P. filters flexible with respect to the materials that are to be degraded. Because always such organisms that can metabolize the delivered matter increase in number, the filters automatically shift to the required function.
Stability. Once such a virtually natural community is established in a filter, invasion and settling of undesirable microorganisms such as pathogens is inhibited. As most soil microorganisms are able to form stages resistant to draught, heat, cold and exposure to chemicals, C.R.O.P. filters can regenerate themselves after disturbances.
Urine Utilization. In our C.R.O.P. Biofiltration Lab at the DLR in Cologne we optimize the capability of the C.R.O.P. filters to convert urine into a nitrate containing solution for use in plant cultivation or fertilizer production. Future research will focus on the ability of the filters to degrade micropollutants and the dynamics of the microbial populations in the filters.
Wet Composting. In cooperation with the project :agrohort situated at the University of Bonn, the filters’ capacity to process plant wastes is investigated. Shredded plant residues are liquefied and degraded in pilot plants. Tests on the use of the resulting solution in soilless vegetable cultivation are in progress.