Page 403 - Refining Biomass Residues for Sustainable Energy and Bioproducts

366 Refining Biomass Residues for Sustainable Energy and Bioproducts

Organic acids such as those that acetic and butyric acids are produced from fer-
mentation of cellulose waste, for example, straw and bagasse (Naik et al., 2010).
Protein and protein polymers used in wool and silk industries are obtained from
wood and cotton cellulose. Food, medicine, and cosmetics acquired from microcrys-
talline cellulose as the feedstock (Naik et al., 2010). Acetone butanol, lactic acid,
and polylactic acids are some of the important products obtained from glucose-
yielding feedstocks (Loh et al., 1999; Rojan et al., 2005). Paper, pulp, bioethanol,
and biogas are the products from lignocellulosic feedstocks. Papers when produced
from forest waste generate both solid and liquid residues of higher lignin and sugar
content, which can be the excellent sources of second generation ethanol (Rathna
et al., 2014). Manganese peroxidase, lignin peroxidase, laccase are some of the
important lignolytic enzymes derived from brewery waste and apple waste. Wastes
generated from agroindustries are of multiphase and multicomponent in nature.
Liquid, solid, and gaseous wastes are made by agroindustries with the ability to pol-
lute soil, water, and air. These wastes need urgent attention. Huge quantity of
wastewater is generated from agroindustries more particularly the food industries. It
also emits some volatile gases (H 2 S) along with some solid wastes (slug). Palm oil
mill releases volatile fatty acids causing air pollution (Fitzherbert et al., 2008).
Organic constituents such as carbohydrate, protein, fat, and oil are the major part in
waste. They bear higher BOD and chemical oxygen demand (COD) with suspended
solids. The presence of higher nutrients in organic waste poses threat to the environ-
ment. Wastewater generated from agroindustries such as rubber-processing and sea-
food industries also contains photopigments of photosynthetic bacteria such as
Chromatium spp. (Prasertsan et al., 1993). Some examples of agroindustrial wastes
and their products are summarized in Table 16.4.
For efficient utilization of bio-based materials, agroindustries have to play a cru-
cial role. With the rising demand of bio-based products the possibility of conflict
between the production of food and bio-based resources is also increasing. In this
situation the use of lignocellulosic materials from grasses, trees, shrubs, crop resi-
dues along with genetically engineered crops for specific applications shows a
beam of light. These, on the other hand, require more efficient technologies.
Growing genetically engineered crops and total removal of crop residues for agroin-
dustrial use may have to face many hurdles as it may enhance soil erosion, degrade
soil quality, and increase pollution due to broader application of fertilizers and pes-
ticides. With the aid of proper genetic engineering, manipulation on biochemical
contents of specific plant tissue with easier processing can be obtained. To achieve
this, still, some questions, for example, basic processes related to gene expression,
growth, development, and chemical metabolism need to be answered.

16.2.2 Characterization of agroindustry wastes
Agroindustrial waste treatment strategies require the knowledge of environmental
quality parameters of wastes. Since the agroindustrial waste residues are rich in
nutrients, a thorough knowledge on the chemical composition will be helpful in