Global stabilisation of continuous bioreactors: tools for analysis and design of feeding laws

[EN] This work revisits the dynamic behaviour of stirred continuous reactors in which a single bioreaction with unknown kinetics occurs. Conditions on the feeding strategy to avoid washing out the biomass and falling in batch operation are obtained. These conditions derive in a closed positively invariant region including the desired operating point. It is stated that no closed orbits may exist in this region and, furthermore, that no fixed point exists but on one of its borders. Therefore, global stability is achieved by finding a feeding law that fulfils the aforementioned invariant conditions and gives a single equilibrium for a first-order dynamics. These results are useful to determine the stability properties of different control laws and, more importantly, to design new ones. The main advantages of the proposed approach are its simplicity and that, differing from previous results, input saturation does not affect stability results. The potentiality of the developed tools is illustrated by means of classical and novel feeding laws. (C) 2017 Elsevier Ltd. All rights reserved.Financed by I216-2016 (UNLP), PICT2014-2394 (ANPCyT) and PIP112-2015-01-00837 (CONICET), Argentina; and by DPI2014-55276-C5-1-R MINECO/AEI/FEDER, UE. The material in this paper was not presented at any conference.De Battista, H.; Jamilis, M.; Garelli, F.; Picó, J. (2018). Global stabilisation of continuous bioreactors: tools for analysis and design of feeding laws. Automatica. 89:340-348. https://doi.org/10.1016/j.automatica.2017.12.041S3403488

Exploring the Biochemical Methane Potential of Wholesale Market Waste from Jordan and Tunisia for a Future Scale-Up of Anaerobic Digestion in Amman and Sfax

3 Figuras.-- 2 TablasLocal open markets, trading fruits and vegetables, are widespread in Mediterranean countries, such as Tunisia and Jordan, producing large amounts of organic waste. Applying an anaerobic digestion process on this substrate makes it crucial to evaluate the waste mixture composition and seasonal variability properly. In this study, after defining an average composition of the fruit and vegetable waste (FVW) mixture produced in Sfax (Tunisia) and Amman (Jordan) in three seasonal intervals (autumn–winter, spring, and summer), the biochemical methane potential (BMP) of an artificially created FVW mixture was individually determined by three European institutions located in Spain, Italy, and Greece. The average BMP from all three seasons and laboratories was 286 ± 52 NmL CH4 g CODadded−1, close to the theoretical maximum yield of 350 NmL CH4 g CODadded−1, indicating a high biodegradability of the waste. Τhe biochemical methane yields of the spring mixtures were not statistically different across the three labs. The most significant differences among the BMP results were obtained for the autumn/winter and the summer mixtures used in Spain, likely due to the variety or ripeness of fruits and vegetables collected in the local markets. In the other two labs in Italy and Greece, no statistical difference was observed for the BMPs of the three season mixtures within the same lab. Therefore, not a critical difference in the biodegradability of such FVW is expected along the different seasons, indicating that the operation of a full-scale digester over a whole year would constantly benefit from the supplementation of a high biochemical methane potential feedstock. Graphical Abstract: [Figure not available: see fulltext.]This work was funded by the project entitled “Employing circular economy approach for OFMSW management within the Mediterranean countries – CEOMED” number A_B.4.2_0058, funded under the ENI CBC MED 2014–2020 programmePeer reviewe