C.R.O.P. – Combined Regenerative Organic food Production. A base for an easy to use system for wastewater reclamation

The basic idea of the project C.R.O.P. is to design a flexible waste processing system for all kinds of liquid and solid organic wastes. The system is envisioned to be combined with soilless plant cultivation for life support purposes during long-term space missions. The core of the C.R.O.P.-System is a microbial trickling filter which is inoculated with a diverse community of soil microorganisms. These are capable to degrade organic matter of all kinds into inorganic compounds, which can be taken up by plants. With regard to wastewater reclamation on Earth the C.R.O.P.-Filter can provide an easy to use and easy to maintain treatment plant for the processing of nitrogenous wastewater into nitrate fertilizer solutions for agricultural use. In our testing facility at the German Aerospace Center in Cologne a set of C.R.O.P.-Filters in operation are monitored regarding their long-term performance in nitrate production. It could already be shown that nitrification occurs in the filters. Ammonium is turned into nitrate so quickly that odour nuisance and toxicity are reduced to a minimum. The application of the resulting solution as fertilizer is currently tested

C.R.O.P. – Combined Regenerative Organic Food Production: Employing the Benefits of Natural Communities

The reutilization of nutrients bound in organic wastes for food crop cultivation is a central topic of BLSS (Bioregenerative Life Support System) research. The conversion of organic wastes into inorganic compounds utilizable by plants proceeds stepwise and each step is carried out by specific microorganisms with varying environmental demands. In BLSS design different steps are often allocated to different treatment units. Each unit is inoculated with selected microbial cultures and provides optimal growth conditions for these. The compartmented set-up is also often used in public wastewater treatment. But as wastewaters usually carry their decomposers with them, specified inoculates are only applied in special cases. Due to the highly variable composition of wastewater, diverse communities of microorganisms are found in treatment plants enabling these to cope with the unpredictable substrate. Although in isolated space habitats, microorganisms necessary for degradation will also be present on wastes and in wastewaters, their diversity will be limited to those species introduced into the system until launch. Therefore, it is crucial to establish a stable microbial community in the waste processing system that is capable to degrade all kinds of wastes, including micropollutants like pharmaceutical residues, before launch. The C.R.O.P. project aims at combining the utilization of liquid and solid organic wastes with soilless plant cultivation. The envisioned waste processing system is a trickling filter designed to join all required functions in one compartment thus reducing size and weight. To achieve this, the filter medium provides habitats with differing conditions so that a diverse microbial community grows as biofilm on its surface. We assume that, once established, such a quasi-natural community makes the system multifunctional with regard to the substrates that can be degraded, and stable with regard to invasion of undesirable microorganisms. Our current research focuses on the characterisation of the system's capability to degrade different substrates like urine and plant wastes and the usability of the filtrate as fertilizer. Molecular analyses revealed a variety of different microorganisms in the filters. Future research will address the question how to introduce specialised microorganisms into the system to enable it to degrade micropollutants, and the question how to maintain these during periods of absence of their substrate

C.R.O.P. - Combined Regenerative Organic food Production: Using trickling filters for wet composting of organic waste in hydroponic greenhouse cultures

In the past decades the upcoming shortage of mineral oil caused intense public debates and research efforts on the subject of alternative fuels and the recycling of plastics. The limited availability of environmentally compatible fertilizer for food production purposes attracted muss less public interest, but is of equal importance. C.R.O.P. is a sustainable concept for the improvement of organic wastes and wastewaters, which combines microbial trickling filters for waste processing with hydroponic plant cultivation on the basis of the resulting nutrient containing solutions. Although the trickling filters are designed as waste processing plants for closed environment systems in the first place, they are also suitable for nutrient recycling in modern hydroponic greenhouse cultures. Wet composting of plant wastes comprises two steps, the first of which is the liquefaction of the solid parts and the second the mineralization of the organic matter. These processes require the presence of several microbial species with differing environmental demands. To enable the simultaneous growth of the necessary organisms in one filter unit, the filter medium has to provide the corresponding habitats. Therefore, our trickling filters contain porous lava rock as filter medium. The small pores of the lava particle form different habitat zones under the growth of the biofilm in which the outer layers provide oxic habitats for aerobic bacteria and anoxic habitats for anaerobic bacteria. Presently, three full-scale trickling filters of the type described with special adaptations for solids processing located at AgroHort Campus Klein-Altendorf of the University of Bonn are in operation. Each filter unit consists of a tank that contains 800l of water and a filter that contains 250l of lava. The water is constantly circulated through the lava filter. Between 5 to 15 kg of shredded plant wastes were added every fortnight to the water (total amount approximately 120 kg). The waste was carried along in the flow, thus also passing the filter, and was liquefied within days. The process resulted in a clear and almost completely odour-free solution. Alter the measurement of mass concentrations of inorganic compounds by ion exchange chromatography the solution is used as stock solution for liquid fertilizer application in growth tests, which are currently in progress. To date we can state that nutrients, especially micronutrients, have to be added when the filter units are solely fed with plant wastes but the consumption of conventional fertilizer is reduced

C.R.O.P. – Combined Regenerative Organic-food Production: Using trickling Filters for Wet Composting in Hydroponic Greenhouse Cultures in Space and on Earth

In the past decades the upcoming shortage of mineral oil caused intense public debates and research efforts on the subject of alternative fuels and the recycling of plastics. The limited availability of environmentally compatible fertilizer for food production purposes attracted much less public interest, but is of equal importance. C.R.O.P. is a sustainable concept for the improvement of organic wastes and wastewaters, which combines microbial trickling filters for waste processing with hydroponic plant cultivation on the basis of the resulting nutrient containing solutions. Although the trickling filters are designed as waste processing plants for closed environment systems in the first place, they are also suitable for nutrient recycling in modern hydroponic greenhouse culture. Wet composting of plant wastes comprises two steps, the first of which is the liquefaction of the solid parts and the second the mineralization of the organic matter. These processes require the presence of several microbial species with differing environmental demands. To enable the simultaneous growth of the necessary organisms in one filter unit, the filter medium has to provide the corresponding habitats. Therefore, our trickling filters contain porous lava rock as filter medium. The small pores of the lava particles form different habitat zones under the growth of the biofilm in which the outer layers provide oxic habitats for aerobic bacteria and anoxic habitats for anaerobic bacteria. Presently, three full-scale trickling filters of the type described with special adaptations for solids processing located at Campus Klein-Altendorf of the University of Bonn are in operation. Each filter unit consists of a tank that contains 800 l of water and a filter that contains 250 l of lava. The water is constantly circulated through the lava filter. Between 5 to 15 kg of shredded plant wastes were added every fortnight to the water (total amount approx. 120 kg). The waste was carried along in the flow, thus also passing the filter, and was liquefied within days. The process resulted in a clear and almost completely odour-free solution. After determination of mass concentrations of inorganic compounds by ion exchange chromatography the solution is used as stock solution for liquid fertilizer application in growth tests, which are currently in progress. To date we can state that nutrients, especially micronutrients, have to be added when the filter units are solely fed with plant wastes but the consumption of conventional fertilizer is reduced