초록
<P><B>Abstract</B></P> <P>This study evaluates the use of non-pretreated thermo-mechanical pulping (TMP) wastewater as a potential substrate for hydrogen production by dark fermentation. Batch incubations were conducted in a temperature gradient incubator at temperatures ranging from 37 to 80 °C, using an inoculum from a thermophilic, xylose-fed, hydrogen-producing fluidised bed reactor. The aim was to assess the short-term response of the microbial communities to the different temperatures with respect to both hydrogen yield and composition of the active microbial community. High throughput sequencing (MiSeq) of the reversely transcribed 16S rRNA showed that <I>Thermoanaerobacterium</I> sp. dominated the active microbial community at 70 °C, resulting in the highest hydrogen yield of 3.6 (±0.1) mmol H<SUB>2</SUB> g<SUP>−1</SUP> COD<SUB>tot</SUB> supplied. Lower hydrogen yields were obtained at the temperature range from 37 to 65 °C, likely due to consumption of the produced hydrogen by homoacetogenesis. No hydrogen production was detected at temperatures above 70 °C. Thermomechanical pulping wastewaters are released at high temperatures (50–80 °C), and thus dark fermentation at 70 °C could be sustained using the heat produced by the pulp and paper plant itself without any requirement for external heating.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dark fermentation of thermomechanical pulping wastewater was studied at 37–80 °C. </LI> <LI> The maximum yield of 3.6 mmol H<SUB>2</SUB> g<SUP>−1</SUP> COD<SUB>tot</SUB> added was obtained at 70 °C. </LI> <LI> Changes of only few °C had clear impact on H<SUB>2</SUB> yield and active microbial community. </LI> <LI> Homoacetogenesis compromised H<SUB>2</SUB> production at temperatures <70 °C. </LI> <LI> Heat from TMP process can be exploited for treating the wastewater at 70 °C. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>