5.7
Strategies to Enhance Biogas Production
There are various strategies to enhance biogas production (Keanoi et al. 2014; Gu
et al. 2015; Amnuaycheewa et al. 2016; Soam et al. 2017). To enhance biogas
production, cow dung addition and effect of other factors have been studied (Keanoi
et al. 2014). The benefit of addition of cow dung and codigestion along with rice
straw was attempted in different mode; as a result, 1650 mL/day methane was
obtained when natural water, rice straw, cow dung, and water hyacinth is used in
the ratio of 2:1:1:1. The recommended C:N ratio was 32: 25. Mustafa et al. emphasize on biological pretreatment strategies to improve the digestibility of substrate,
and worker used Pleurotus ostreatus. According to a report, addition of increasing
amount of goat manure, dairy manure, with other agricultural waste, such as straw
material, for example, wheat straw (WS), corn stalks (CS), and rice straw (RS) (at C/
N ratio of 35:61), is helpful in increasing biogas production. A similar report was
given by Li et al. (2014) where biogas was enhanced by adding dairy manure with a
mixture of three straw rice straw, corn stalks, and wheat straw. In another attempt
C/N ratio was improved by adding urea, in optimized condition 1% NaOHpretreated rice, and biogas was obtained after 15 days, 514 L/kg VS/day.
In another attempt, biogas production was enhanced by optimizing inoculum to
substrate ratio (Candia-García et al. 2018). The optimum condition was temp. 5
C to
27
C time 60 days and biogas produced was 410 L/kgVS at 0.8 of I/S ratio, and
methane obtained 70%.
5.7.1 Enhancing Biogas Production via Application of Microbial
Consortia in Pretreatment
Recently, some workers reported use of thermophilic microbial consortium (MC1)
(Yuan et al. 2014). This pretreatment method is novel in the sense that it has
opportunity to digest lignocellulosic biomass with high efficiency to produce biogas
and methane because of high mass of ethanol, acetic acid, propionic acid, and
butyric acid.
A novel microbial consortia was developed named as BYND-5 which was based
on mixture of microbes from mesophilic microbes that were mixed in order to digest
the rice straw. Digestion efficiency of BYND-5 was checked for rice straw which
was around 49% after 7 days (Yan et al. 2012). The species were identified by
molecular techniques called as ARDRA (Amplified ribosomal DNA restriction
analysis).
5.7.2 Improved Biogas Production by Bioaugmentation Technique
Another method to improve biogas production reported was bioaugmentation technique by use of two fungi in anaerobic two-stage system for digesting two substrates,
corn silage and cattail (Table 5.3).
5 Biogas: An Effective and Common Energy Tool – Part III
131
Strategies to Enhance Biogas Production
There are various strategies to enhance biogas production (Keanoi et al. 2014; Gu
et al. 2015; Amnuaycheewa et al. 2016; Soam et al. 2017). To enhance biogas
production, cow dung addition and effect of other factors have been studied (Keanoi
et al. 2014). The benefit of addition of cow dung and codigestion along with rice
straw was attempted in different mode; as a result, 1650 mL/day methane was
obtained when natural water, rice straw, cow dung, and water hyacinth is used in
the ratio of 2:1:1:1. The recommended C:N ratio was 32: 25. Mustafa et al. emphasize on biological pretreatment strategies to improve the digestibility of substrate,
and worker used Pleurotus ostreatus. According to a report, addition of increasing
amount of goat manure, dairy manure, with other agricultural waste, such as straw
material, for example, wheat straw (WS), corn stalks (CS), and rice straw (RS) (at C/
N ratio of 35:61), is helpful in increasing biogas production. A similar report was
given by Li et al. (2014) where biogas was enhanced by adding dairy manure with a
mixture of three straw rice straw, corn stalks, and wheat straw. In another attempt
C/N ratio was improved by adding urea, in optimized condition 1% NaOHpretreated rice, and biogas was obtained after 15 days, 514 L/kg VS/day.
In another attempt, biogas production was enhanced by optimizing inoculum to
substrate ratio (Candia-García et al. 2018). The optimum condition was temp. 5
C to
27
C time 60 days and biogas produced was 410 L/kgVS at 0.8 of I/S ratio, and
methane obtained 70%.
5.7.1 Enhancing Biogas Production via Application of Microbial
Consortia in Pretreatment
Recently, some workers reported use of thermophilic microbial consortium (MC1)
(Yuan et al. 2014). This pretreatment method is novel in the sense that it has
opportunity to digest lignocellulosic biomass with high efficiency to produce biogas
and methane because of high mass of ethanol, acetic acid, propionic acid, and
butyric acid.
A novel microbial consortia was developed named as BYND-5 which was based
on mixture of microbes from mesophilic microbes that were mixed in order to digest
the rice straw. Digestion efficiency of BYND-5 was checked for rice straw which
was around 49% after 7 days (Yan et al. 2012). The species were identified by
molecular techniques called as ARDRA (Amplified ribosomal DNA restriction
analysis).
5.7.2 Improved Biogas Production by Bioaugmentation Technique
Another method to improve biogas production reported was bioaugmentation technique by use of two fungi in anaerobic two-stage system for digesting two substrates,
corn silage and cattail (Table 5.3).
5 Biogas: An Effective and Common Energy Tool – Part III
131