Effects of the operational conditions on the production of 1,3-propanediol derived from glycerol in anaerobic granular sludge reactors

• Published in: Water science and technology 2017-02, Vol.75 (3-4), p.963-970
• Main Authors: Nakazawa, Mitsue M, Florencio, Lourdinha, Kato, Mario T, Gavazza, Savia, Sanz, Jose L
• Format: Article
• Language: English
• Subjects: 1,3-Propanediol; Acetates; Acetic acid; Alternative energy sources; Anaerobic conditions; Anaerobiosis; Archaea; Bicarbonates; Biodegradation; Biodiesel fuels; Bioengineering; Bioreactors; Bioreactors - microbiology; Biotechnology; Calcium chloride; Carbonates; Continuous production; Ethanol; Euryarchaeota - metabolism; Experiments; Fermentation; Glycerol; Glycerol - metabolism; Heat shock; Hydrogen; Inoculation; Methanogenesis; Methanogenic archaea; Microorganisms; Mixed culture; Propionic acid; Propylene Glycols - analysis; Reactors; Sewage - chemistry; Sewage - microbiology; Sludge; Sodium; Sodium bicarbonate; Surface Properties; Upflow anaerobic sludge blanket reactors; Variables; Variance analysis; Yeast; Yeasts; Yields
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2016.577

The aim of this study has been to produce 1,3-propanediol (1,3-PDO) from glycerol (gly) fermentation by means of a microbial mixed culture (granular sludge), as well as to establish the operational conditions of two up-flow anaerobic sludge blanket (UASB) reactors in order to achieve a maximum 1,3-PDO yield. The UASB reactors with initial pH values set at 6.8 and 5.5 were operated at 30 °C during 165 days. Thirteen variables were previously screened by a Plackett-Burman (PB) design; results showed that yeast extract, MgSO and methanogenesis inhibition (by heat shock) showed a positive effect, whereas high glycerol concentration, tryptone and CaCl showed a negative impact on the 1,3-PDO produced by glycerol degradation. Following four experimental periods, the highest average yield of 0.43 mol 1,3-PDO mol gly was achieved when sodium bicarbonate was added to the reactors. Propionate and acetate were also produced and a high microorganism diversity was detected; however, the restrictive operational conditions of the reactors led to the death of the methanogenic archaea. Nevertheless, the continuous production of 1,3-PDO from glycerol within UASB reactors inoculated with granular sludge can be considered highly feasible.