A transdisciplinary approach that integrates thermochemical conversions and biological transformations for valorizing C-content and chemical energy of anaerobically digested sewage sludge and producing biopolymers (polyhydroxyalkanoates, PHA) and drop-in chemicals (crotonic acid) has been presented here. Hydrothermal carbonization has increased by 10-times the soluble COD of sewage sludge, allowing it to split 44-54% of its COD into an aqueous phase (HTCap) enriched in small fermentable organic molecules; the coupling of acidogenic fermentation and aerobic fermentation converted these substrates first into volatile fatty acids (20% of CODHTCap) and then into PHA (about 20% of CODVFA). The extraction of microbial biomass with dimethyl carbonate (DMC) allowed high quality PHA to be produced, with a high molecular weight (0.9 MDa) and a percentage of medium chain monomers (hydroxyvalerate and hydrohexanoate) close to 12%. The postextraction microbial biomass, still containing a relevant portion of "unextractable" PHA, was last treated at 300 °C to selectively convert the PHA-backbone into crotonic acid with a 42% yield on PHA content basis.
Polyhydroxyalkanoates and Crotonic Acid from Anaerobically Digested Sewage Sludge / Samori C.; Kiwan A.; Torri C.; Conti R.; Galletti P.; Tagliavini E.. - In: ACS SUSTAINABLE CHEMISTRY & ENGINEERING. - ISSN 2168-0485. - ELETTRONICO. - 7:12(2019), pp. 10266-10273. [10.1021/acssuschemeng.8b06615]
Polyhydroxyalkanoates and Crotonic Acid from Anaerobically Digested Sewage Sludge
Samori C.
;Kiwan A.;Torri C.;Galletti P.;Tagliavini E.
2019
Abstract
A transdisciplinary approach that integrates thermochemical conversions and biological transformations for valorizing C-content and chemical energy of anaerobically digested sewage sludge and producing biopolymers (polyhydroxyalkanoates, PHA) and drop-in chemicals (crotonic acid) has been presented here. Hydrothermal carbonization has increased by 10-times the soluble COD of sewage sludge, allowing it to split 44-54% of its COD into an aqueous phase (HTCap) enriched in small fermentable organic molecules; the coupling of acidogenic fermentation and aerobic fermentation converted these substrates first into volatile fatty acids (20% of CODHTCap) and then into PHA (about 20% of CODVFA). The extraction of microbial biomass with dimethyl carbonate (DMC) allowed high quality PHA to be produced, with a high molecular weight (0.9 MDa) and a percentage of medium chain monomers (hydroxyvalerate and hydrohexanoate) close to 12%. The postextraction microbial biomass, still containing a relevant portion of "unextractable" PHA, was last treated at 300 °C to selectively convert the PHA-backbone into crotonic acid with a 42% yield on PHA content basis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
