content from being converted to biogas, which affects the final methane yield.
However, a variety of pretreatments (below discussed) have been shown to be
effective at breaking microalgae cell walls and increasing methane yield
(Angelidaki and Ahring 2000; Alzate et al. 2012).
Cultivation of microalgae under nitrogen deficiency is “well-known” to stimulate lipid accumulation (Chisti 2007). Theoretically, the higher the lipid content of
microalgae cells, the higher their calorific value and hence the higher their methane
yield. However, a high lipid content does not usually correlate with a high methane
yield. Therefore, the content of inert organic matter, rather than the content
energy-rich macromolecules, is believed to have a stronger impact on the final
methane yield (González-Fernandez et al. 2012).
The high content of proteins observed in several microalgae species results in
high concentrations of ammonia nitrogen during anaerobic degradation. Ammonia
Table 2 Cell wall composition of microalgae
Microalgae species
Cell wall (%
w/w)
Cell wall composition (%)
References
Carbohydrates Proteins c.n.i.
a
Chlorella vulgaris
(F)
20.0
30.00
2.46
67.54 Abo-Shady et al.
(1993)
Chlorella vulgaris
(S)
26.0
35.00
1.73
63.27 Abo-Shady et al.
(1993)
Kircheriella lunaris
23.0
75.00
3.96
21.04 Abo-Shady et al.
(1993)
Klebsormidium
flaccidum
36.7
38.00
22.60
39.40 Domozych et al.
(1980)
Ulothrix belkae
25.0
39.00
24.00
37.00 Domozych et al.
(1980)
Pleurastrum
terrestre
41.0
31.50
37.30
31.20 Domozych et al.
(1980)
Pseudendoclonium
basiliense
12.8
30.00
20.00
50.00 Domozych et al.
(1980)
Chlorella
Saccharophila
╶
54.00
1.70
44.30 Blumreisinger
et al. (1983)
Chlorella fusca
╶
68.00
11.00
20.00 Blumreisinger
et al. (1983)
Chlorella fusca
╶
80.00
7.00
13.00 Loos and Meindl
(1982)
Monoraphidium
braunii
╶
47.00
16.00
37.00 Blumreisinger
et al. (1983)
Ankistrodesmus
densus
╶
32.00
14.00
54.00 Blumreisinger
et al. (1983)
Scenedesmus
obliquus
╶
39.00
15.00
46.00 Blumreisinger
et al. (1983)
a c.n.i. stands for content not identified
250
F. Passos et al.
However, a variety of pretreatments (below discussed) have been shown to be
effective at breaking microalgae cell walls and increasing methane yield
(Angelidaki and Ahring 2000; Alzate et al. 2012).
Cultivation of microalgae under nitrogen deficiency is “well-known” to stimulate lipid accumulation (Chisti 2007). Theoretically, the higher the lipid content of
microalgae cells, the higher their calorific value and hence the higher their methane
yield. However, a high lipid content does not usually correlate with a high methane
yield. Therefore, the content of inert organic matter, rather than the content
energy-rich macromolecules, is believed to have a stronger impact on the final
methane yield (González-Fernandez et al. 2012).
The high content of proteins observed in several microalgae species results in
high concentrations of ammonia nitrogen during anaerobic degradation. Ammonia
Table 2 Cell wall composition of microalgae
Microalgae species
Cell wall (%
w/w)
Cell wall composition (%)
References
Carbohydrates Proteins c.n.i.
a
Chlorella vulgaris
(F)
20.0
30.00
2.46
67.54 Abo-Shady et al.
(1993)
Chlorella vulgaris
(S)
26.0
35.00
1.73
63.27 Abo-Shady et al.
(1993)
Kircheriella lunaris
23.0
75.00
3.96
21.04 Abo-Shady et al.
(1993)
Klebsormidium
flaccidum
36.7
38.00
22.60
39.40 Domozych et al.
(1980)
Ulothrix belkae
25.0
39.00
24.00
37.00 Domozych et al.
(1980)
Pleurastrum
terrestre
41.0
31.50
37.30
31.20 Domozych et al.
(1980)
Pseudendoclonium
basiliense
12.8
30.00
20.00
50.00 Domozych et al.
(1980)
Chlorella
Saccharophila
╶
54.00
1.70
44.30 Blumreisinger
et al. (1983)
Chlorella fusca
╶
68.00
11.00
20.00 Blumreisinger
et al. (1983)
Chlorella fusca
╶
80.00
7.00
13.00 Loos and Meindl
(1982)
Monoraphidium
braunii
╶
47.00
16.00
37.00 Blumreisinger
et al. (1983)
Ankistrodesmus
densus
╶
32.00
14.00
54.00 Blumreisinger
et al. (1983)
Scenedesmus
obliquus
╶
39.00
15.00
46.00 Blumreisinger
et al. (1983)
a c.n.i. stands for content not identified
250
F. Passos et al.