3.9
Factors Affecting Biogas Production Operational
Parameters of Biogas Production
Anaerobic digestion is a convenient technology to generate energy from wastes. For
the successful process, number of factors needs to be optimized. Every bacterium
has different living environment. The acidogenic bacteria requires different environment than methanogenic archaea. In the case of mixed culture, the need of the
methanogenic bacteria should be considered with priority because of its nature (strict
anaerobes, longer RT, and slow growth). To avoid the imbalance of AD, the
two-stage process has developed. Here, each group of microorganisms have the
optimum environmental condition (Table 3.8).
Factors Which Affect the Production of Biogas Are Follows
1. pH
2. Temperature
3. Organic loading rate
4. Hydraulic retention time
5. Ratio of carbon to nitrogen (C/N)
6. Toxicants
7. Mixing/agitation
Table 3.7 The methanogenesis reaction
Acetate
CH 3 COOH ! CH 4 + CO 2
Carbon monoxide
4CO + 2H 2 0 ! CH 4 + 3H 2 CO 3
Dimethylamine
2(CH 3 ) 2 NH + 2H 2 O ! 3CH 4 + CO 2 + 2NH 3
Formate
4HCOOH ! CH 4 + CO 2 + 2H 2 O
Hydrogen
4H 2 + CO 2 ! CH 4 + 2H 2 O
Methanol
4CH 3 OH ! 3CH 4 + CO 2 + 2H 2 O
Methylamine
4(CH 3 )NH 2 + 2H 2 O ! 3CH 4 + CO 2 + 4NH 3
Methyl mercaptans
2(CH3) 2 S + 3H 2 O ! 3CH 4 + CO 2 + H 2 S
Metals
4Me
+ 8H
+ + CO 2 ! 4Me
++ + CH 4 + 2H 2 0
Trimethylamine
4(CH 3 )NH + 6H 2 O ! 9CH 4 + 3CO 2 + 4NH 3
Modified from Demirel and Scherer (2008)
Table 3.8 Different steps and important parameters to carry out a successful anaerobic digestion
process
pH
Redox
potential
Temperature
C/N
ratio
C/N/P/S
ratio
Trace
elements
Hydrolysis/
acidogenesis
5.2–6.3 +400 to
À300 mV
25–35
C
1 0 –45 500:15:5:3 –
Acetogenesis/
methanogenesis
6.7–7.5 <
À250 mV
Mesophilic
30–40
C
20–30 600:15:5:3 Ni, Co,
Mo, Se
Thermophilic
50–60
C
90
S. Elangovan et al.
Factors Affecting Biogas Production Operational
Parameters of Biogas Production
Anaerobic digestion is a convenient technology to generate energy from wastes. For
the successful process, number of factors needs to be optimized. Every bacterium
has different living environment. The acidogenic bacteria requires different environment than methanogenic archaea. In the case of mixed culture, the need of the
methanogenic bacteria should be considered with priority because of its nature (strict
anaerobes, longer RT, and slow growth). To avoid the imbalance of AD, the
two-stage process has developed. Here, each group of microorganisms have the
optimum environmental condition (Table 3.8).
Factors Which Affect the Production of Biogas Are Follows
1. pH
2. Temperature
3. Organic loading rate
4. Hydraulic retention time
5. Ratio of carbon to nitrogen (C/N)
6. Toxicants
7. Mixing/agitation
Table 3.7 The methanogenesis reaction
Acetate
CH 3 COOH ! CH 4 + CO 2
Carbon monoxide
4CO + 2H 2 0 ! CH 4 + 3H 2 CO 3
Dimethylamine
2(CH 3 ) 2 NH + 2H 2 O ! 3CH 4 + CO 2 + 2NH 3
Formate
4HCOOH ! CH 4 + CO 2 + 2H 2 O
Hydrogen
4H 2 + CO 2 ! CH 4 + 2H 2 O
Methanol
4CH 3 OH ! 3CH 4 + CO 2 + 2H 2 O
Methylamine
4(CH 3 )NH 2 + 2H 2 O ! 3CH 4 + CO 2 + 4NH 3
Methyl mercaptans
2(CH3) 2 S + 3H 2 O ! 3CH 4 + CO 2 + H 2 S
Metals
4Me
+ 8H
+ + CO 2 ! 4Me
++ + CH 4 + 2H 2 0
Trimethylamine
4(CH 3 )NH + 6H 2 O ! 9CH 4 + 3CO 2 + 4NH 3
Modified from Demirel and Scherer (2008)
Table 3.8 Different steps and important parameters to carry out a successful anaerobic digestion
process
pH
Redox
potential
Temperature
C/N
ratio
C/N/P/S
ratio
Trace
elements
Hydrolysis/
acidogenesis
5.2–6.3 +400 to
À300 mV
25–35
C
1 0 –45 500:15:5:3 –
Acetogenesis/
methanogenesis
6.7–7.5 <
À250 mV
Mesophilic
30–40
C
20–30 600:15:5:3 Ni, Co,
Mo, Se
Thermophilic
50–60
C
90
S. Elangovan et al.