prone to corrosion, so it needs regular maintenance and monitoring. All these factors
contribute to a lifespan of 8 years. Furthermore, presence of any fibrous material
hinders the movement of the drum (Rajendran et al. 2012). Because of inefficient
agitation, deposition of solids occurs restraining the exposure of the substrate to
microorganisms (Singh et al. 1997).
2.2.3.3 Plug Flow Digesters
In 1957, South Africa used this type of digester design for the first time (Ghosh and
Bhattacherjee 2013). High-density polyethylene is used for construction (Lansing
et al. 2008). This model consists of a narrow and long tank. The inlet and outlet are
located opposite to each other. The parts above ground are inlet and outlet, while
other parts are kept in an inclined position underground. The two processes,
acidogenesis and methanogenesis are separated due to the inclined position creating
a two-phase system. The digestate flows at the other end as a new substrate is added
through the inlet. A shed roof or gable is used to cover the digester to avoid
temperature fluctuations and provide insulation (An et al. 1997; Bouallagui et al.
2003; Ferrer et al. 2009, 2011). The comparatively lesser lifespan makes it economically less viable. The shorter lifespan is because of the fragile nature of PVC which is
subjected to extreme conditions and forceful mechanical contact (Nzila et al. 2012).
This model has the advantage of simple design, adaptability to extreme conditions,
easy handling, easy installation, reasonable retention time, and low capital cost
(Ghosh and Bhattacherjee 2013). There are no moving parts so failure risks are
reduced (Singh et al. 1997). However, certain disadvantages such as less biogas
production, the slow solid conversion, and absence of agitation are also associated
with this model (Ghosh and Bhattacherjee 2013).
2.3
Range of Waste Utilization in Biogas Production
A diverse range of waste types can be utilized for waste to energy technologies like
anaerobic digestion (AD). Different types of organic waste include food waste,
animal dung or livestock manure, agricultural waste, sewage sludge, industrial
waste, and the organic portion of municipal solid waste (Khalil et al. 2019). These
waste types can be very harmful to the environment and human beings when openly
dumped (Raheem et al. 2016). Table 2.1 compares the biogas production from
different types of waste, digester and energy potential (Fig. 2.4).
The biogas generation potential of cattle dung varies from 56 to 68 m
3 , fats biogas
potential varies from 826 to 1200 m
3 , and that of pig slurry varies from 11 to 25 m
3 .
The biogas yield and electricity generation of every waste is given per ton of fresh
matter (Achinas et al. 2017).
40
M. N. Anwar et al.
contribute to a lifespan of 8 years. Furthermore, presence of any fibrous material
hinders the movement of the drum (Rajendran et al. 2012). Because of inefficient
agitation, deposition of solids occurs restraining the exposure of the substrate to
microorganisms (Singh et al. 1997).
2.2.3.3 Plug Flow Digesters
In 1957, South Africa used this type of digester design for the first time (Ghosh and
Bhattacherjee 2013). High-density polyethylene is used for construction (Lansing
et al. 2008). This model consists of a narrow and long tank. The inlet and outlet are
located opposite to each other. The parts above ground are inlet and outlet, while
other parts are kept in an inclined position underground. The two processes,
acidogenesis and methanogenesis are separated due to the inclined position creating
a two-phase system. The digestate flows at the other end as a new substrate is added
through the inlet. A shed roof or gable is used to cover the digester to avoid
temperature fluctuations and provide insulation (An et al. 1997; Bouallagui et al.
2003; Ferrer et al. 2009, 2011). The comparatively lesser lifespan makes it economically less viable. The shorter lifespan is because of the fragile nature of PVC which is
subjected to extreme conditions and forceful mechanical contact (Nzila et al. 2012).
This model has the advantage of simple design, adaptability to extreme conditions,
easy handling, easy installation, reasonable retention time, and low capital cost
(Ghosh and Bhattacherjee 2013). There are no moving parts so failure risks are
reduced (Singh et al. 1997). However, certain disadvantages such as less biogas
production, the slow solid conversion, and absence of agitation are also associated
with this model (Ghosh and Bhattacherjee 2013).
2.3
Range of Waste Utilization in Biogas Production
A diverse range of waste types can be utilized for waste to energy technologies like
anaerobic digestion (AD). Different types of organic waste include food waste,
animal dung or livestock manure, agricultural waste, sewage sludge, industrial
waste, and the organic portion of municipal solid waste (Khalil et al. 2019). These
waste types can be very harmful to the environment and human beings when openly
dumped (Raheem et al. 2016). Table 2.1 compares the biogas production from
different types of waste, digester and energy potential (Fig. 2.4).
The biogas generation potential of cattle dung varies from 56 to 68 m
3 , fats biogas
potential varies from 826 to 1200 m
3 , and that of pig slurry varies from 11 to 25 m
3 .
The biogas yield and electricity generation of every waste is given per ton of fresh
matter (Achinas et al. 2017).
40
M. N. Anwar et al.