related to the conversion of the carbon source into methane,
while maintaining the activity of the microbial community
requires the supply of balanced amounts of macro and
microelements.
A microbial cell is formed mainly by CHONPS, constituting approx. 95% of its weight; the rest are micronutrients
such as potassium, calcium, magnesium, zinc, among others.
In biodigesters, micronutrient deprivation results in a less
stable and efficient process with changes in the microbial
community, especially the decrease in the concentration of
Methanosarcina
(a
high-performance
methanogen)
(Wintsche et al. 2016). A biodigester kept in operation for
long periods can begin to suffer acidification even with the
decrease in the feeding rate, which may be the result of
nutritional imbalance. Lebuhn et al. (2008) demonstrated the
recovery of a collapsed system with the addition of
micronutrients. Different studies point to several limiting
micronutrients, the most common of which are cobalt,
nickel, molybdenum, tungsten and selenium (Pobeheim et al.
2011; Plugge et al. 2009; Banks et al. 2012; Munk and
Lebuhn 2014). Therefore, the feeding of a biodigester must
be well evaluated and planned in order to provide all the
nutrients necessary for the survival and multiplication of the
microorganisms present there, which makes it essential to
know the microbial community present. A well-diversified
microbial community is essential in cases where food and
environmental conditions are constantly changing (Kallistova et al. 2014).
Olive oil, for example, despite having enormous methane
production potential, probably could not be used as an
exclusive feed in a biodigester due to the absence of nitrogen
and minerals such as phosphorus, zinc magnesium, copper,
manganese and selenium, essential for cell multiplication
and activity. However, this material can be used in codigestion with another material so that the balance of nutrients
is established and the gas productivity has little impact.
Other advantages of codigestion are positive synergistic
effects on microorganisms, better process stability and
Table 2 Characterization of the
solids content and the
biochemical potential of methane
production of diverse food wastes
carried out at the CIBiogás
Biogas Laboratory
Substrate
ST
(g/kg)
SV
(g/kg)
LN biogas /
kg sv
LN CH4 /
kg sv
LN biogas /
kg subst
LN CH4 /
kg subst
Methane
content (%)
Chocolate
powder
950.0
878.4
371.7
234.7
310.2
195.8
63
Black beans
848.0
961.5
564.3
332.3
460.1
271.0
59
Olive oil
999.1
999.9
1237.9
868.0
1236.5
867.1
70
Oil
973.3
996.1
1127.0
778.7
1092.6
754.9
69
Animal fat
999.5
999.9
1103.5
655.7
1103.1
655.4
58,8
Meat
321.4
971.9
781.4
562.8
244.1
175.8
72
Sausages
354.8
925.1
958.3
665.7
314.6
218.5
69
Onions
90.3
936.5
605.8
320.4
51.2
27.1
53
Garlic
345.0
950.7
157.4
36.8
51.6
12.1
23
TS = total solids, VS = volatile solids in dry base, LN = normal liters, subst = substrate
Fig. 5 Methane production
potential and concentration in
biogas for different types of food.
NL CH4 = normal liters of
methane
Bioconversion of Food Waste to Biogas
105
while maintaining the activity of the microbial community
requires the supply of balanced amounts of macro and
microelements.
A microbial cell is formed mainly by CHONPS, constituting approx. 95% of its weight; the rest are micronutrients
such as potassium, calcium, magnesium, zinc, among others.
In biodigesters, micronutrient deprivation results in a less
stable and efficient process with changes in the microbial
community, especially the decrease in the concentration of
Methanosarcina
(a
high-performance
methanogen)
(Wintsche et al. 2016). A biodigester kept in operation for
long periods can begin to suffer acidification even with the
decrease in the feeding rate, which may be the result of
nutritional imbalance. Lebuhn et al. (2008) demonstrated the
recovery of a collapsed system with the addition of
micronutrients. Different studies point to several limiting
micronutrients, the most common of which are cobalt,
nickel, molybdenum, tungsten and selenium (Pobeheim et al.
2011; Plugge et al. 2009; Banks et al. 2012; Munk and
Lebuhn 2014). Therefore, the feeding of a biodigester must
be well evaluated and planned in order to provide all the
nutrients necessary for the survival and multiplication of the
microorganisms present there, which makes it essential to
know the microbial community present. A well-diversified
microbial community is essential in cases where food and
environmental conditions are constantly changing (Kallistova et al. 2014).
Olive oil, for example, despite having enormous methane
production potential, probably could not be used as an
exclusive feed in a biodigester due to the absence of nitrogen
and minerals such as phosphorus, zinc magnesium, copper,
manganese and selenium, essential for cell multiplication
and activity. However, this material can be used in codigestion with another material so that the balance of nutrients
is established and the gas productivity has little impact.
Other advantages of codigestion are positive synergistic
effects on microorganisms, better process stability and
Table 2 Characterization of the
solids content and the
biochemical potential of methane
production of diverse food wastes
carried out at the CIBiogás
Biogas Laboratory
Substrate
ST
(g/kg)
SV
(g/kg)
LN biogas /
kg sv
LN CH4 /
kg sv
LN biogas /
kg subst
LN CH4 /
kg subst
Methane
content (%)
Chocolate
powder
950.0
878.4
371.7
234.7
310.2
195.8
63
Black beans
848.0
961.5
564.3
332.3
460.1
271.0
59
Olive oil
999.1
999.9
1237.9
868.0
1236.5
867.1
70
Oil
973.3
996.1
1127.0
778.7
1092.6
754.9
69
Animal fat
999.5
999.9
1103.5
655.7
1103.1
655.4
58,8
Meat
321.4
971.9
781.4
562.8
244.1
175.8
72
Sausages
354.8
925.1
958.3
665.7
314.6
218.5
69
Onions
90.3
936.5
605.8
320.4
51.2
27.1
53
Garlic
345.0
950.7
157.4
36.8
51.6
12.1
23
TS = total solids, VS = volatile solids in dry base, LN = normal liters, subst = substrate
Fig. 5 Methane production
potential and concentration in
biogas for different types of food.
NL CH4 = normal liters of
methane
Bioconversion of Food Waste to Biogas
105