scrubbing method. Also, energy demand is low for amine scrubbing method (Bauer
et al. 2013a, b). But the energy requirement is low for adsorption method with low
microbial contamination, safety and flexibility—a guaranteed measure. Meanwhile,
the cryogenic technology ensures the power consumption to be nil (Collet et al.
2017), thus making it a viable efficient fuel (Sahota et al. 2018). On the whole, the
biological methods are environmentally sustainable with minimised greenhouse gas
emissions.
The environmental indicators prove that the highly efficient method is the
biological method which can yield negative outcomes such as low CH 4 loss, less
water use and 208,837 kW-hy
À energy consumption (in algal-bacterial
photobioreactor), low CH 4 loss, low energy consumption and less water use (in in
situ chemoautotrophic method) (Angelidaki et al. 2018).
(d) Operational Indicators
The operational indicators include the pressure, temperature, consumables and
partial load range. Pressurised water scrubbing technique works at lower flow rates,
and pre-cleaning is not necessary, but biological contamination adds to its disadvantage with high amount of water requirement. The chemical dehydrogenation method
encompasses the high process efficiency. For the process of pressure swing adsorption technology, purging pressure, adsorbents used, feeding pressure and cycle time
(Grande 2011) contribute to the operational issues, and those issues must be
refactored to achieve the desired end product.
In contrast to this, foaming, amine loss and corrosion persist as the operational
issues for amine scrubbing method. Hence, amine solution must be added as
consumables. Addition of antifouling agent + drying agent, organic solvent,
activated carbon, oil + activated carbon must be added as consumables for
pressurised water scrubbing method, organic physical scrubbing method, adsorption method and membrane technology, respectively (Sahota et al. 2018; Bauer
et al. 2013a, b).
Operating pressure (4–8 bar g, 4–7 bar g, 4–8 bar g, 4–8 bar g, 4–7 bar g, 80 bar
and 8–10 bar g) is required for pressurised water scrubbing method, pressure swing
adsorption method, organic physical scrubbing method, membrane technology,
cryogenic technology and chemical dehydrogenation method, respectively. The
pressure requirement is very less for supersonic method. Also, for vacuum swing
adsorption method, atmospheric pressure is required. Among the membrane separation methods, the operational life is longer for inorganic membrane separation
technique. In polymeric membrane separation method, the major problem lies in
the formation of plasticisation that degrades the membranes. The adsorption capacity
and specific surface area are high in mixed matrix membrane separation technology.
Also, the polymeric membrane separation technology seems to be a dry process with
less chemical usage (Vrboba and Karel 2017). The compression and the additional
chemical requirement is nil for cryogenic technology (Sahota et al. 2018).
The temperature requirement is about 25–40
C, 70–80
C, 120–160
C, À196
C,
270
C, 85
C and 40
C for pressurised water scrubbing method, organic physical
272
B. S. Dhanya et al.
et al. 2013a, b). But the energy requirement is low for adsorption method with low
microbial contamination, safety and flexibility—a guaranteed measure. Meanwhile,
the cryogenic technology ensures the power consumption to be nil (Collet et al.
2017), thus making it a viable efficient fuel (Sahota et al. 2018). On the whole, the
biological methods are environmentally sustainable with minimised greenhouse gas
emissions.
The environmental indicators prove that the highly efficient method is the
biological method which can yield negative outcomes such as low CH 4 loss, less
water use and 208,837 kW-hy
À energy consumption (in algal-bacterial
photobioreactor), low CH 4 loss, low energy consumption and less water use (in in
situ chemoautotrophic method) (Angelidaki et al. 2018).
(d) Operational Indicators
The operational indicators include the pressure, temperature, consumables and
partial load range. Pressurised water scrubbing technique works at lower flow rates,
and pre-cleaning is not necessary, but biological contamination adds to its disadvantage with high amount of water requirement. The chemical dehydrogenation method
encompasses the high process efficiency. For the process of pressure swing adsorption technology, purging pressure, adsorbents used, feeding pressure and cycle time
(Grande 2011) contribute to the operational issues, and those issues must be
refactored to achieve the desired end product.
In contrast to this, foaming, amine loss and corrosion persist as the operational
issues for amine scrubbing method. Hence, amine solution must be added as
consumables. Addition of antifouling agent + drying agent, organic solvent,
activated carbon, oil + activated carbon must be added as consumables for
pressurised water scrubbing method, organic physical scrubbing method, adsorption method and membrane technology, respectively (Sahota et al. 2018; Bauer
et al. 2013a, b).
Operating pressure (4–8 bar g, 4–7 bar g, 4–8 bar g, 4–8 bar g, 4–7 bar g, 80 bar
and 8–10 bar g) is required for pressurised water scrubbing method, pressure swing
adsorption method, organic physical scrubbing method, membrane technology,
cryogenic technology and chemical dehydrogenation method, respectively. The
pressure requirement is very less for supersonic method. Also, for vacuum swing
adsorption method, atmospheric pressure is required. Among the membrane separation methods, the operational life is longer for inorganic membrane separation
technique. In polymeric membrane separation method, the major problem lies in
the formation of plasticisation that degrades the membranes. The adsorption capacity
and specific surface area are high in mixed matrix membrane separation technology.
Also, the polymeric membrane separation technology seems to be a dry process with
less chemical usage (Vrboba and Karel 2017). The compression and the additional
chemical requirement is nil for cryogenic technology (Sahota et al. 2018).
The temperature requirement is about 25–40
C, 70–80
C, 120–160
C, À196
C,
270
C, 85
C and 40
C for pressurised water scrubbing method, organic physical
272
B. S. Dhanya et al.