Effect of thermal hydrolysis pretreatment on volatile fatty acids production in sludge acidification and subsequent polyhydroxyalkanoates production
[Display omitted] •Thermal hydrolyzed sludge produced 44.6% more VFAs than raw sludge at 35 °C.•High temperature (55 °C) increased the VFAs yield of raw sludge by 15.7%.•High temperature (55 °C) yet reduced the VFAs yield of TH-sludge by 12.2%.•Acidified liquid of TH-sludge achieved a yield 34.6% PH...
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Veröffentlicht in: | Bioresource technology 2019-05, Vol.279, p.92-100 |
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Sprache: | eng |
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•Thermal hydrolyzed sludge produced 44.6% more VFAs than raw sludge at 35 °C.•High temperature (55 °C) increased the VFAs yield of raw sludge by 15.7%.•High temperature (55 °C) yet reduced the VFAs yield of TH-sludge by 12.2%.•Acidified liquid of TH-sludge achieved a yield 34.6% PHAs/DCW in PHAs production.•TH-sludge is a suitable substrate for VFAs and PHAs production.
The study compared the differences in VFAs production between raw sludge and thermal hydrolyzed sludge (TH-sludge) at different temperature (35 °C and 55 °C) in four semi-continuous acidification reactors. Optimal VFAs yield was obtained from TH-sludge at 35 °C (0.22 gVFACOD/gVS), 44.6% higher than raw sludge at 35 °C, since the advantage of TH-sludge in SCOD solubilization overcame its disadvantage of lower carbon biodegradability. Moreover, high temperature (55 °C) was proved to aid the acidification of raw sludge by 15.7% (in YVFAs), but inhibit that of TH-sludge by 12.2%, mainly due to the suppressed microbial activities under heat. Microbial community analysis showed that TH-sludge had a larger proportion of acidogenic microbes than raw sludge, mainly attributing to the increase of Selenomonadales (37.3% vs. 3.7%); high temperature enriched thermophilic proteolytic microbes, Anaerobaculum and Coprothermobacter. Finally, optimal acidified liquid from TH-sludge at 35 °C was applied for PHAs production and achieved a competitive yield of 34.6% PHAs/DCW. |
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ISSN: | 0960-8524 1873-2976 |
DOI: | 10.1016/j.biortech.2019.01.077 |