Co-digestion of Cheese Whey With Sewage Sludge for Caproic Acid Production: Role of Microbiome and Polyhydroxyalkanoates Potential Production

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The main aim of this work was to evaluate the efficiency of producing caproic acid and other volatile fatty acids using a co-digestion between cheese whey and sewage sludge in a continuous reactor. The effect of two different feeding regimes (one and two per day) and three hydraulic retention times (HRT) (15, 10 and 6 days) on the organic acids production were studied. The optimal conditions for the process were 10 days HRT, 2 feeding cycles per day, reaching a maximum degree of acidification of 44%. Under these conditions, the most abundant organic acid was caproic acid. The analysis of the microbial community dynamics in the reactor during the HRT changes revealed a microbiome enriched in organisms involved in caproic acid production. Additionally, the production of polyhydroxyalkanoates using the organic acids stream as feeding was verified in a fed-batch experiment obtaining a copolymer formed by hydroxybutyrate, hydroxyvalerate and hydroxyhexanoate.This study received funding from the European FEDER framework program CTQ2017-88292-R and from the Spanish Ministry of Economy and Competitiveness (MINECO), also by Xunta de Galicia under the grant agreement for Competitive Reference Research Groups (GRC) (ED431C 2017/66). The authors would like to thank the companies EMALCSA S.A., and INNOLACT S.L. for their contributionXunta de Galicia; ED431C 2017/6