Page 547 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Bioconversion of marine waste biomass for biofuel and value-added products recovery 495

initial stage in AD technique, complex organic polymers can be converted into sim-
ple components, for example, proteins, lipids, and carbohydrate polymers are
decomposed into amino acids, long-chain fatty acids, and sugars, respectively. The
fermentative bacteria convert the VFAs into carbon dioxide, hydrogen, and acetic
acid by acidogenesis process. In addition to that, organic acids were converted into
acetate and carbon dioxide by acetogenic bacteria. Methanogenesis is the last step
of AD, in which a diversity of methanogenic bacteria convert acetate, carbon diox-
ide, and hydrogen to produce methane (Weiland, 2010).

22.4.1.2 Biodiesel from fish waste
Biofuel is derived from triglycerides, and it is the combination of mono-alkyl-esters
of long-chain fatty acids. Biofuel derived from oils (vegetable) and fat (animal) is
recognized as biodiesel by the process called transesterification process which
entails transfer of glycerin to alcohol (methanol or ethanol). This biofuel is consid-
ered as a fractional or entire alternate of petro diesel. Waste fish oil derived from
redundant piece of fish is utilized for biodiesel production (Dewil et al., 2007).

22.4.1.3 Ethanol from sea weed
Seaweeds are the marine microalgae considered as a source of biofuel and act as a
helping hand to meet the energy demand (Deng and H¨ agg, 2010). Because they are
obviously cultivated in the sea, they need no room for agricultural lands. Seaweeds
can be categorized into three types:
red (rhodophyceae);
brown (phaeophyceae); and

green (chlorophyceae).

These weeds comprise 50% 70% of carbohydrates on the basis of weight (dry).
The chief carbohydrate present in the red algae is agar or carrageenan, while algi-
nate, mannitol, laminarin, or fucoidan is present in brown algae. In addition to that,
seaweeds have cellulose and hemicellulose. Due to their complex structure, these
seaweeds are used for the anaerobic fermentation, which pretend to be difficult for
the hydrolyzing process, through both physicochemical and biological methods
(Palatsi et al., 2010).

22.4.2 Edible products
Fish is the significant ingredient of the human diet. Fishing is the very old profes-
sion, and the products obtained from fish are also considered as important. Because
of the emergence of foremost preservation technique, the product, either food or
nonfood, coming from the marine waste is of international trade importance even
from the historical perspective (Taneja and Singh, 2012). Crustacean residues,
marine organisms, and seaweeds are used as a constituent of food, and in cosmetics,
as well as used in medicine, nutrition, and health. Because of the unique biodiver-
sity, marine sources are sound recognized and that suggests a well-built source to
utilize marine organisms for healthy foods and also for new functional food