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Parallel Session C – University of Copenhagen

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Parallel Session C 

Daniel Meyer-Kohlstock; Bauhaus-Universität Weimar FertiPlus: Local Organic Cycles in Urban Europe

Pelin Kocaturk; Wageningen UR-Alterra & Copenhagen University; FertiPlus: Nutrient recovery from digestate by using biochar and clinoptilolite

Bruno Glaser; Martin Luther University Halle-Wittenberg (Other project): Biochar as option for sustainable resource management

Ulf Raesfeld, Weimar, Biorefine: Integrated nutrient recovery via co-fermentation of wood ash and pig slurry.

Rapporteurs report

The first presentation by Daniel Meyer-Kohlstock (FertiPlus) was about local organic cycles in urban Europe. The main aim of this study was to acquire an open data system to identify and localize methods to process organic waste in urban agriculture system. A tool box system was designed as an innovative approach to quantify and regulate the nutrient contents of waste water sludge, urine and faeces and recycling them into the urban agricultural system. This tool is mainly designed for the urban sites to monitor the nutrient flow from urban waste (organic) into the agriculture.

The second presentation from Pelin Kocaturk (FertiPlus) was about use of biochar and clinoptilolite to recover nutrients from the digestate. It seems from her study that the clay mineral clinoptilolite could be used as a potential source to up concentrate nutrients (NH4+ and K+) in the liquid fraction of the digestate as these nutrients were found to be significantly absorbed onto the clay mineral surface, but was found to be less effective in terms of PO4- sorption. Biochar was found more effective to up concentrate PO4- in the liquid fraction of the digestate than clinoptilolite.

The third presentation given by Bruno Glaser was about biochar’s role in sustainable resource management. It was concluded that biochar from wood biomass is more stable than organic matter and can be used for carbon sequestration purpose, but has a negative result in terms of N availability. In such case biochar pre-treatment (NPK enrichment) prior soil application could be an alternative strategy to get the positive results in terms of crop growth and enhancement in soil properties (physical, chemical and biological). It was also found that biochar aromaticity (H:C ratio) is an important measure to check stability and is inversely related to biochar reactivity (O:C ratio). Legalization of biochar and associated products is necessary to develop specific guidelines.

The fourth presentation made by Ulf Raesfeld (Biorefine) was about integrated nutrient recovery via co-fermentation of wood ash and pig slurry. The main research question derived from his presentation is: “Is there a future for digestate from co-fermentation of wood ash and pig slurry to be used as a potential fertilizer?” It was realized that the effect of the highly alkaline pH of wood ash into slurry on NH3 and other GHGs emissions should be investigated carefully before using such product as fertilizer.

Over all conclusions 

(1) Develop an open data system to identify and localize methods to process organic waste in urban agriculture system.

(2) The clay mineral clinoptilolite could be used as a potential source to up concentrate nutrients (NH4+ and K+) in the liquid fraction of the digestate as these nutrients were found to be significantly absorbed onto the clay mineral surface, but was found to be less effective in terms of PO4- sorption.

(3) The biochar from wood biomass is more stable than organic matter and can be used for carbon sequestration purpose, but has a negative result in terms of N availability.

(4) Is there a future for digestate from co-fermentation of wood ash and pig slurry to be used as a potential fertilizer? (this research is still ongoing and results obtained are preliminary).

Compiled by Raghunath Subedi (ReUseWaste) and Ivona Sigurnjak (INEMAD).

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