Aquatic Plant Feedstocks such as water hyacinth, micro and macro algae, and sea
weeds are suitable for bioenergy production. These feedstocks have easily
hydrolysable sugars, contain lower lignin, and do not compete with land resources
used as compared to arable food crop cultivation. The co-digestion of alga sludge
and waste paper leading to methane production rate up to 1607 Æ 17 ml/day was
reported. Both water hyacinth and micro algae are mostly used as feed material
because of their higher gas yield.
Farming Residues Farming activities produce plenty of biomass residues as agricultural waste which can be used as feedstock for anaerobic digestion, such as
cotton, maize, and rice residues. However, high lignin content of such residues
can lead to poor biodegradability and minimal biogas production. Pretreated lignocellulosic can improve biodegradability and the biogas production. Several reports
showed sustainable and higher gas yield by using pretreatment, additional nutrients,
and co-digestion of farming residues and other substrates (Chandra et al. 2012; Nges
et al. (2012).
Energy Crops Energy crops such as C-4 plants are good candidate-substrate for
biogas production. Grass is one such substrate, which is easily available throughout
the year and reported to produce high methane content (~70–80%). Corn and Sudan
grass are some of the most popular co-substrates in Germany and Austria. Biogas or
methane production of about 0.655 to 0.72–0.77 m
3 /kg of VSS from maize silage,
and non-acidified or acidified maize, and ~5–181 Nm
3 /tonne from sugarcane were
reported during anaerobic digestion. Although energy crops have potential, lignocellulosic content is still an issue; thus pretreatment prior to anaerobic digestion is
needed for better biogas production. When the sorghum was pretreated with sodium
hydroxide, an increased methane production (from 8% to 19%) was reported.
3.5.2 Community-Based Feedstock
Community-based feedstock includes municipal solid waste, organic fraction of
municipality waste, sewage sludge, kitchen waste (Ziana and Rajesh 2015; Apte
et al. 2013; Ogur and Mbatia 2013), garden waste, institutional waste, wholesale
fruit and vegetable market waste, etc.
Municipal Solid Waste (MSW) MSW comes from housing, institutions, and
commercial establishments. If discarded untreated, it is both burden on treatment
plants and a waste of energy and nutrients, and it could rather be used as a substrate
for biogas production. MSW typically contain ~65% of food waste from the kitchen.
Reports suggest that blending kitchen waste and cow manure as a co-substrate at
mesophilic condition could generate ~ 60–69% methane, and ~10 kg of kitchen
waste could produce ~2.292 m
3 of biogas (Reddy 2017; Singh and Sankarlal 2015;
Haftu et al. 2018).
72
S. Elangovan et al.
weeds are suitable for bioenergy production. These feedstocks have easily
hydrolysable sugars, contain lower lignin, and do not compete with land resources
used as compared to arable food crop cultivation. The co-digestion of alga sludge
and waste paper leading to methane production rate up to 1607 Æ 17 ml/day was
reported. Both water hyacinth and micro algae are mostly used as feed material
because of their higher gas yield.
Farming Residues Farming activities produce plenty of biomass residues as agricultural waste which can be used as feedstock for anaerobic digestion, such as
cotton, maize, and rice residues. However, high lignin content of such residues
can lead to poor biodegradability and minimal biogas production. Pretreated lignocellulosic can improve biodegradability and the biogas production. Several reports
showed sustainable and higher gas yield by using pretreatment, additional nutrients,
and co-digestion of farming residues and other substrates (Chandra et al. 2012; Nges
et al. (2012).
Energy Crops Energy crops such as C-4 plants are good candidate-substrate for
biogas production. Grass is one such substrate, which is easily available throughout
the year and reported to produce high methane content (~70–80%). Corn and Sudan
grass are some of the most popular co-substrates in Germany and Austria. Biogas or
methane production of about 0.655 to 0.72–0.77 m
3 /kg of VSS from maize silage,
and non-acidified or acidified maize, and ~5–181 Nm
3 /tonne from sugarcane were
reported during anaerobic digestion. Although energy crops have potential, lignocellulosic content is still an issue; thus pretreatment prior to anaerobic digestion is
needed for better biogas production. When the sorghum was pretreated with sodium
hydroxide, an increased methane production (from 8% to 19%) was reported.
3.5.2 Community-Based Feedstock
Community-based feedstock includes municipal solid waste, organic fraction of
municipality waste, sewage sludge, kitchen waste (Ziana and Rajesh 2015; Apte
et al. 2013; Ogur and Mbatia 2013), garden waste, institutional waste, wholesale
fruit and vegetable market waste, etc.
Municipal Solid Waste (MSW) MSW comes from housing, institutions, and
commercial establishments. If discarded untreated, it is both burden on treatment
plants and a waste of energy and nutrients, and it could rather be used as a substrate
for biogas production. MSW typically contain ~65% of food waste from the kitchen.
Reports suggest that blending kitchen waste and cow manure as a co-substrate at
mesophilic condition could generate ~ 60–69% methane, and ~10 kg of kitchen
waste could produce ~2.292 m
3 of biogas (Reddy 2017; Singh and Sankarlal 2015;
Haftu et al. 2018).
72
S. Elangovan et al.