32
2 High-Efficient Anaerobic Fermentation Technology of Organic …
the maximum total gas production was 704 mL, which happened in the process of
drying treatment. Similar results of biogas production were found in the control test
and treatments with aeration and ultrasonic, suggesting that these methods failed
to enhance the production efficiency of H 2 of the PADRs (Fig. 2.14). Whereas, the
cumulative production of biogas of the PADRs subjected to pre-treatment of acid,
heat, alkali, and chloroform were all less than that of the control test (631 mL). This
indicated that these treatments were able to inhibit the hydrogen-consuming bacteria
as well as the hydrogen-producing bacteria in the PADRs.
Hydrogen and carbon dioxide are main building blocks of the generated biogas,
as well as small quantities of methane in several treatments. The proportions of
H 2 and CH 4 on conditions of using the various treatment methods are illustrated
in Fig. 2.14. The results are obtained on conditions of a fixed initial pH (6.0) and
10 g/L consumption of glucose for 48 h. The hydrogen displayed higher fractions
in the treatment reactors, than in the control test (32.42%), except for the treatments
with acid and chloroform. The results indicated that the highest proportion of H 2
was 49.13% while using the drying treatment method, and 47.23% and 31.88%,
respectively in treatments with alkaline and acid. The hydrogen accounted for 48.20%
and 49.13%, respectively in the total biogas during the heat and drying treatments,
without observation of methane production in either of them.
Hence, the selection of a suitable temperature at which the PADRs were treated
thermally is a critical link for the search of an effective approach for enriching bacteria
producing hydrogen while suppressing bacteria consuming hydrogen. Dissimilar to
the BES treatments, the hydrogen only displayed a concentration of 2.1% in the case
that CHCl 3 was utilized for inhibiting the production of methane from acetate and
H 2 /CO 2 . These results of biohydrogen production revealed that one can effectively
apply the optimal conditions for drying (49.13%) and BES (46.93%) treatments to
prompt production of hydrogen and inhibit methanogens. Whereas, the application of
BES costs high, and BES has other effects on bacteria producing hydrogen: it is also
capable of inhibiting production of methane downstream if methane and hydrogen
were the co-produced. Among the eight treatment methods, the most effective one for
enriching bacteria producing hydrogen and providing the highest yield of hydrogen
(172.94 mL H 2 /g glucose) is drying for 24 h at 60 °C.
2.2.3.2 Effects of Pre-treatment on pH
It can be seen that the final pH changed in the range of 4.11–5.68 for each treatment
reactor. Among the eight treatments, the drying, BES, and aeration treatment methods
showed the final pH values of 5.68, 5.67, 5.66, respectively, which were approximate
to 5.59, final pH of the untreated PADRs. In comparison, for fermentation reactors
using the PADRs treated with acid, alkaline, and heat the final pH values were
all below 5.0, which inhibited the production of bacteria producing hydrogen. The
optimal pH value for hydrogen production is in the range of 5.5–6.0. These results
indicated that, due to anaerobic fermentation, the various treatments led to dissimilar
buffering capacity in the production systems of bio-hydrogen.
2 High-Efficient Anaerobic Fermentation Technology of Organic …
the maximum total gas production was 704 mL, which happened in the process of
drying treatment. Similar results of biogas production were found in the control test
and treatments with aeration and ultrasonic, suggesting that these methods failed
to enhance the production efficiency of H 2 of the PADRs (Fig. 2.14). Whereas, the
cumulative production of biogas of the PADRs subjected to pre-treatment of acid,
heat, alkali, and chloroform were all less than that of the control test (631 mL). This
indicated that these treatments were able to inhibit the hydrogen-consuming bacteria
as well as the hydrogen-producing bacteria in the PADRs.
Hydrogen and carbon dioxide are main building blocks of the generated biogas,
as well as small quantities of methane in several treatments. The proportions of
H 2 and CH 4 on conditions of using the various treatment methods are illustrated
in Fig. 2.14. The results are obtained on conditions of a fixed initial pH (6.0) and
10 g/L consumption of glucose for 48 h. The hydrogen displayed higher fractions
in the treatment reactors, than in the control test (32.42%), except for the treatments
with acid and chloroform. The results indicated that the highest proportion of H 2
was 49.13% while using the drying treatment method, and 47.23% and 31.88%,
respectively in treatments with alkaline and acid. The hydrogen accounted for 48.20%
and 49.13%, respectively in the total biogas during the heat and drying treatments,
without observation of methane production in either of them.
Hence, the selection of a suitable temperature at which the PADRs were treated
thermally is a critical link for the search of an effective approach for enriching bacteria
producing hydrogen while suppressing bacteria consuming hydrogen. Dissimilar to
the BES treatments, the hydrogen only displayed a concentration of 2.1% in the case
that CHCl 3 was utilized for inhibiting the production of methane from acetate and
H 2 /CO 2 . These results of biohydrogen production revealed that one can effectively
apply the optimal conditions for drying (49.13%) and BES (46.93%) treatments to
prompt production of hydrogen and inhibit methanogens. Whereas, the application of
BES costs high, and BES has other effects on bacteria producing hydrogen: it is also
capable of inhibiting production of methane downstream if methane and hydrogen
were the co-produced. Among the eight treatment methods, the most effective one for
enriching bacteria producing hydrogen and providing the highest yield of hydrogen
(172.94 mL H 2 /g glucose) is drying for 24 h at 60 °C.
2.2.3.2 Effects of Pre-treatment on pH
It can be seen that the final pH changed in the range of 4.11–5.68 for each treatment
reactor. Among the eight treatments, the drying, BES, and aeration treatment methods
showed the final pH values of 5.68, 5.67, 5.66, respectively, which were approximate
to 5.59, final pH of the untreated PADRs. In comparison, for fermentation reactors
using the PADRs treated with acid, alkaline, and heat the final pH values were
all below 5.0, which inhibited the production of bacteria producing hydrogen. The
optimal pH value for hydrogen production is in the range of 5.5–6.0. These results
indicated that, due to anaerobic fermentation, the various treatments led to dissimilar
buffering capacity in the production systems of bio-hydrogen.