Long‐term operation of a two‐stage polyhydroxyalkanoates production process from hardwood sulphite spent liquor

Abstract

ABSTRACTBACKGROUNDThe development of sustainable industrial processes demands the recovery and transformation of their by‐products. The production of polyhydroxyalkanoates (PHAs) by mixed microbial cultures (MMC) is one of the available routes. This study evaluated the possibility of applying a two‐step PHAs production process using an industrial by‐product, hardwood sulphite spent liquor (HSSL), as feedstock for a MMC. The first step consisted in the selection of PHAs‐storing microorganisms using an aerobic dynamic feeding strategy followed by a second step, accumulation.RESULTSThe selected MMC, despite not being able to use the main carbon source of HSSL, lignosulphonates, revealed the capacity to consume acetate and xylose to accumulate poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) and glucose biopolymer. The maximum PHAs content was relatively low, 6.6%, with a maximum production yield of 0.49 C‐mmol HA C‐mmol S−1 during the selection stage.CONCLUSIONA MMC was able to adapt to HSSL by consuming acetate and xylose. The imposed operational conditions resulted in a partial selection of the culture, since only acetate‐consuming organisms experienced a real feast/famine regime, resulting in low PHAs production. © 2015 Society of Chemical Industry