References

15

1.5

Conclusion

Circular economy is mooted to loop in the excess energy dissipated from human

activities, which gets dispersed into environment in the form of greenhouse gases

leading to global warming. International Renewable Energy Agency (IRENA) has

called for a global energy transition toward complete de-carbonization of energy

sector by the year 2040. Water treatment boards around the world have partnered

with various environmental technological companies and have initiated zero waste

movement, an ambitious plan to divert organic waste from landfills and incinerators

to AcD. Steps have been taken to reduce carbon foot print by investing in infrastruc-

tural upgradation of AcD especially for treatment of commercial food waste with

existing wastewater anaerobic sludge treatment plants. AcD has been identified as a

key technology to attain net zero. Many countries have even linked bio-methane pro-

duced from AcD to the national grid for gas transmission. Few nations have reported

more than 100% growth in popularity of AD and have set up hundreds of digester

plants and are operating them successfully.

Steps are being taken by the scientific community to address the issue of natural

methane emission into atmosphere from organics-rich land environment, water

bodies and ocean sediments, substantial livestocks population, and man-made

landfills. Methane mitigation efforts are taken on all frontiers to cut the flow of

methane into the atmosphere that is presently contributing to global warming.

One such technology is being reviewed for methane mitigation from cattle by

supplementing feed with anti-methanogen IgY antibodies [25], while AcD is way

forward envisaged for zero waste. Few logistics issues pertaining to feedstock and

its transportation have already been highlighted earlier in this chapter, and this

has to be addressed in future. In this regard, it can be noted that WWTPs are the

best examples for case study to see through the reason for its success and it can be

chiefly attributed to continuous supply of wastewater, sewage treatment plant (STP)

generating uninterrupted solid sludge (feed stocks), digesters designed for retaining

microbial granules, thus reducing energy and cost for transportation. And yet again

linking other feedstock (like food waste) with WWTP leading to AcD has further

enhanced the scope of the key technology for visualizing a world of net zero waste.

References

1 Neves, L., Goncalo, E., Oliveira, R. et al. (2008). Influence of composition in the

biomethanation potential of restaurant waste at mesophilic temperatures. Waste

Management 28: 965–972.

2 Appels, L., Baeyens, J., Degreve, J. et al. (2008). Principles and potential of the

anaerobic digestion of waste-activated sludge. Progress in Energy and Combustion

Service 34: 755–781.

3 Arlene, K. (2020). Why co-digest food waste and sludge. https://www.waste360

.com/food-waste/why-co-digest-food-waste-and-sludge-part-1 (accessed 20

August 2020).