The main achievement during the project period has been the construction completion of the DIGESTAIR prototype and its commissioning with real waste, as planned in the DOA. The steps required to achieve this goal are summarized below:
(i) Completion of the assembly of all the components.
(ii) Completion of the installation of the electrical panel and the wiring and automation of all the components of the prototype.
(iii) Programming of the operating automatisms in the PLC (Programmable Logic Controller) of the prototype.
(iv) First operating tests of critical units using water: vacuum transfer system, pasteurization, membrane filtration system.
(v) Inoculum collection and conditioning. Specifically, inoculum was collected from the anaerobic digestion plant for the treatment of the organic fraction of municipal solid waste in San Sebastian. The inoculum has been characterized, and it has been necessary to sieve it, filter it and make a partial dilution to remove undesired contaminants.
(vi) The individual waste streams have been adequately characterized and the BMP tests results showed a higher biogas and methane potential for food waste > bioplastic > manure, where the highest methane production was obtained at mesophilic temperature.
(vii) Collection of waste to be treated in the experimental prototype: food waste from catering, biodegradable plastics and cardboard, pig slurry as "black water", and preparation of the influent mixture according to the previous study carried out to determine the composition of waste generated on board.
(viii) Start-up of the prototype with the conditioned inoculum and the prepared waste mixture.
(ix) Experimental validation of the prototype fed with real waste, similar to that generated in aircraft.
(x) Construction of the calibration layout of the mathematical simulation model: the model that will was used to calibrate the anaerobic co-digestion was constructed by using the WEST® simulation platform under the Plant-Wide Modelling (PWM) methodology developed by Ceit.
(xi) Calibration/Validation of the model: The experimental calibration of the model has consisted in the estimation of the values of the unknown parameters of the mathematical model that make their predictions and reproduces the experimental observations as much as possible.
(xii) Construction of the global DIGESTAIR solution model: the model that have been used to reproduce the functioning of the whole system was constructed by using the WEST® simulation platform under the PWM methodology.
(xiii) Scenario analysis by simulation: Once the anaerobic digestion was calibrated, it was possible to carry out the simulation studies. This evaluation has been based on the following aspects: (1) Determination of the feasibility of proposed technologies -DIGESTAIR solution- to treat the waste generated during the flight; (2); Definition of the optimal theoretical operating conditions of the two-stage anaerobic digestion configuration and the membrane configuration; (3) Comparison of the performance of such treatments in different conditions (different types of flights); (4) Assessment of the transferability of the ADP to other applications such as cruises.
Regarding the exploitation plan, the cost-benefits analysis has been done taking into account three periods: the industrialization period, the entry into market (short & mid-term comprising product launch and references creation) and settlement and consolidation in the market (sales period). In addition, R&D efforts from this project till industrialization would be added to embrace the overall remaining envisage activities since now and finishing with DIGESTAIR maturity enough to propose industrialization. This phase is envisaged to encompass about two years. During the industrialization period, the outcomes of DIGESTAIR will be brought from a TRL6 to a TRL8. This means important expenses in engineering, and material and subcontracting. It will also last another two years.
Finally, numerous dissemination actions have been carried out during the project, including a presentation at 3 international conferences, an article in the most widely read newspaper in Spain and a radio interview.
