0000000000068011
AUTHOR
Hanne P. Tähti
Thermophilic hydrogen production from cellulose with rumen fluid enrichment cultures: Effects of different heat treatments
Elevated temperatures (52, 60 and 65 °C) were used to enrich hydrogen producers on cellulose from cow rumen fluid. Methanogens were inhibited with two different heat treatments. Hydrogen production was considerable at 60 °C with the highest H2 yield of 0.44 mol-H2 mol-hexose -1 (1.93 mol-H2 mol-hexose-degraded-1) as obtained without heat treatment and with acetate and ethanol as the main fermentation products. H2 production rates and yields were controlled by cellulose degradation that was at the highest 21%. The optimum temperature and pH for H2 production of the rumen fluid enrichment culture were 62 °C and 7.3, respectively. The enrichments at 52 and 60 °C contained mainly bacteria from …
Hydrogen and methane production in extreme thermophilic conditions in two-stage (upflow anaerobic sludge bed) UASB reactor system
Abstract Two-stage hydrogen and methane production in extreme thermophilic (70 °C) conditions was demonstrated for the first time in UASB-reactor system. Inoculum used in hydrogen and methane reactors was granular sludge from mesophilic internal circulation reactor and was first acclimated for extreme thermophilic conditions. In hydrogen reactor, operated with hydraulic retention time (HRT) of 5 h and organic loading rate (OLR) of 25.1 kg COD/m 3 /d, hydrogen yield was 0.73 mol/mol glucose added . Methane was produced in second stage from hydrogen reactor effluent. In methane reactor operated with HRT of 13 h and OLR of 7.8 kg COD/m 3 /d, methane yield was 117.5 ml/g COD added . These resul…
Effects of heat treatment on hydrogen production potential and microbial community of thermophilic compost enrichment cultures
Cellulosic plant and waste materials are potential resources for fermentative hydrogen production. In this study, hydrogen producing, cellulolytic cultures were enriched from compost material at 52, 60 and 70°C. Highest cellulose degradation and highest H(2) yield were 57% and 1.4 mol-H(2) mol-hexose(-1) (2.4 mol-H(2) mol-hexose-degraded(-1)), respectively, obtained at 52°C with the heat-treated (80°C for 20 min) enrichment culture. Heat-treatments as well as the sequential enrichments decreased the diversity of microbial communities. The enrichments contained mainly bacteria from families Thermoanaerobacteriaceae and Clostridiaceae, from which a bacterium closely related to Thermoanaerobiu…
One-stage H2 and CH4 and two-stage H2+ CH4 production from grass silage and from solid and liquid fractions of NaOH pre-treated grass silage
Abstract In the present study, mesophilic CH4 production from grass silage in a one-stage process was compared with the combined thermophilic H2 and mesophilic CH4 production in a two-stage process. In addition, solid and liquid fractions separated from NaOH pre-treated grass silage were also used as substrates. Results showed that higher CH4 yield was obtained from grass silage in a two-stage process (467 ml g−1 volatile solids (VS)original) compared with a one-stage process (431 ml g−1 VSoriginal). Similarly, CH4 yield from solid fraction increased from 252 to 413 ml g−1 VSoriginal whereas CH4 yield from liquid fraction decreased from 82 to 60 ml g−1 VSoriginal in a two-stage compared to …