Page 25 - Refining Biomass Residues for Sustainable Energy and Bioproducts

4 Refining Biomass Residues for Sustainable Energy and Bioproducts

to the humans when they can wrapped in plastic. Once they are disposed in the
environment, due to the wrapped plastic, the degradation of them is postponed,
which spreads diseases. Methane and other greenhouse gases are produced when a
lot of space in landfills is occupied by the nonrecyclable cardboards such as pizza
boxes and disposable coffee cups and other wastages. Apart from MSWs, there are
some other SWs such as agriculture and forestry residues; animal manure and sew-
age sludge should be pretreated and then disposed into the environment once they
become nontoxic to environmental ecosystems.
There are several waste-management techniques that are commonly used to
treat the wastes and convert them into nontoxic or beneficial form such as land-
filling, biological, and thermal processing of wastes. Landfilling techniques are
most efficient for MSWs. This method is more expensive due to site cost and
lack of accommodation of the large volume of waste being produced. Once waste
is landfilled, the possibility for the recovery of resources from those landfilled
area is less, and those wastes release toxins, leachates, and greenhouse gases.
These released products can associate with landfilling and decrease the efficiency
of wastes degradation. In biological processing the wastes can be processed by
the microorganisms either aerobically or anaerobically. For the biological proces-
sing of any type of SWs requires large area for the degradation of the organic
wastes, and the time consumed for this process is high, and the process is more
expensive. Some materials should be pretreated before being allowed to the bio-
logical treatment, especially plastics and other SWs require pretreatments before
their biological degradation (Eckenfelder and O’Connor, 2013). Thermal proces-
sing is a process in which the waste materials are degraded by carried out the
process or applying higher temperature. Thermal processing includes several tech-
niques such as incineration, gasification, and pyrolysis. These processes have
more advantages than others, but finally it results in production of huge amount
of greenhouse gases and carcinogenic volatile organics. For the thermal proces-
sing of SWs, it requires drying as pretreatment, which is high energy requiring
process and expensive (Lu et al., 2011). Hydrothermal wet oxidation is another
technique used for the treatment of hazardous SWs. In this process the wastes
are degraded in water under specific conditions: temperature ranges from 150 C

to 320 C, and pressure is 20 150 bar (Munir et al., 2017; Anthraper et al.,

2018).
This chapter mainly focused on the biorefineries of SWs from different origins.
It describes the sources of SWs such as agricultural and forestry residues, MSWs
and their properties, animal manure, and sewage sludge; their biomass pretreat-
ments also explained in detail. The different techniques used for the degradation
of SWs, such as landfills, biological processing, thermal processing, are explained.
Especially the methods of pyrolysis, characteristics, and their features are
explained in detail for thermal processing of SWs. Several liquid products and
their physicochemical properties, chemical composition, and phases are discussed,
and some other refinery products and their future trends are also explained in this
chapter.