Contribution A Letude De La Granulation Thermoplastique En Melangeur Haute Vitesse Et En Lit Dair Fluidise

Author : Sidonie Durieux
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (143 download)

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Download or read book Contribution À L'étude Des Granules Aérobies Et À la Production D'ALE written by Sidonie Durieux and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerobic granular sludge allows multiple reactions and fast-settling among the same tank (Morgenroth et al., 1997). In addition, the potential valorization of ALE (alginate-like exopolymers) seems an interesting route for circular economy of wastewaters (van Leeuwen et al., 2018).Granular sludge processes are already used for domestic and industrial wastewaters treatment (Pronk et al., 2015). This thesis was interested in studying the possibility to valorize ALE from particular (industrial), highly loaded wastewaters. Viability of this valorization from highly loaded wastewaters was first ensured by studying granulation with high OLR (organic loading rate), various COD/N and low COD/P. Following, the impact of operating conditions on slow growers (phosphate- and glycogen-accumulating organisms, PAO and GAO), and their own impact on granulation have been studied. Finally, granulation and ALE production were monitored for high loading rates, that led to modification of operating conditions, in particular the food-to-microorganisms (F/M) ratio.The main objectives of this thesis were:- Get better knowledge on the granulation process under different COD/N ratio in the feeding.- Understand the dependence between the specific organic loading rate (or food/microorganism ratio (F/M)) and the ALE production rate.The approach was based on both experimental studies and modelling. Reactors used were semi-pilot of 17 L. They were operated as bubble column sequenced batch reactors (SBR) with an anaerobic/aerobic cycle. The granulation was obtained by progressive increase of the organic loading rate (OLR) from 1 to 3 kg COD/m3/d. The COD substrates were glucose, VFA (acetate and propionate) and peptone. Modelling was used to interpret the experimentally obtained results using the SUMO software from Dynamita.In the first chapter of this thesis the granulation under high and low COD/N was compared. Whereas granulation was successful for high COD/N, low COD/N led to deflocculation. Studying the microbial activity, it was observed that nitrifiers had been washed out, due to the high selection pressure. This nitrification loss led to an increased ammonium concentration and corresponding free ammonia concentration, causing deflocculation and microbial shift. Those effects were compared with effects of low COD/N on already obtained granules. Granules maintained, even under low COD/N, and could even be favorized.In the second chapter, the role of PAO and GAO in granulation, under high COD/P ratio, was also studied by comparing reactor with and without washout of those slow growers. The presence of PAO and GAO ensured anaerobic consumption of the COD. When they were washed out filamentous growth was observed at the same time as a sharp decrease of the anaerobic COD consumption and phosphates release, indicating the loss of PAO and GAO. A replicable shift of population was observed. Decreasing the selection pressure allowed the formation of granules, thanks to another microbial shift, which relied on completely different metabolisms as the anaerobic COD consumption never rose again. The results obtained were compared with simulation.Finally, the third chapter studied the impact of F/M (0.3 to 0.65 g CODS/g VSS/d) by increasing progressively the OLR, on the aerobic granular sludge system stability and evaluated the ALE production under these conditions. The high organic loading rate imposed a short SRT that led to a low ALE concentration among the obtained granules and the ALE concentration was observed to be correlated to the applied F/M.As a conclusion, different challenges to be faced for valorization of industrial wastewaters have been studied during this thesis, in order to bring new knowledge to better face them.