Stabilised BW from anaerobic digestion systems (AnMBR or dAD, Solution S7), will be used as compost for local gardening (public parks, training activities in schools, etc.) substituting commercial compost. For that, on the one hand, reliability of different low-cost options for stabilisation of AnMBR digestate (from S7a) such as drying (AIGUASOL, LEITAT), domestic co-composting by mixture with fresh BWs (LEITAT) and vermicomposting (LEITAT) will be compared at laboratory before selection optimisation and scale-up and demonstration at pilot scale in Frontrunner buildings. Target foreseen includes the mass conversion yield of 0.55kg compost/kg digestate.
On the other hand, an innovative compost cultivator prototype (developed by ALCN) will co-compost digestate from dAD in S7b solution together with fresh biomass clippings from the garden and greenhouse and will generate plants at the same time in a self-irrigating system. Any odours will also be eliminated by the plants and their roots in the closed system. A liquid fertiliser will be collected at the bottom of the system, hygienised, and can be sold or traded for organic waste with the neighbours. The best service model for this process will be co-elaborated with local and regional stakeholders. This model can possibly be expanded to bigger scale for decentralised urban composting activities. The operational performance of the prototype will be firstly tested before demonstration and installation in Demo 3 at building scale. Replication of the optimal solution will be offered to stakeholders as renting/leasing service.