GHG emission from sewage treatment 41% lower than previous data
A collaborative study of NARO with several research institutes recalculated the nitrous oxide and methane emission factor based on actual measurements of greenhouse gases generated in swine and cattle wastewater treatment facilities. As a result, we have found that the domestic emission factor of nitrous oxide was found to be over-estimated at present. The estimated value of greenhouse gas emissions using the latest emission factor (total amount of nitrous oxide and methane) associated with swine and cattle sewage treatment was reduced by 600kt CO2 eq. (41%) annually as compared with the estimated value using the current emission factor. The nitrous oxide and methane emission factor calculated this time will be adopted as a new standard for Japan.
The estimated greenhouse gas emission from livestock production accounts for 41% of the greenhouse gas emissions from agriculture in Japan, and development of a livestock production system with much lesser environmental impact is required. Meanwhile, the current emission of nitrous oxide and methane from the livestock manure which is estimated using the emission factor based on laboratory data is found to be deviated from the actual value. Hence it was necessary to calculate the emission amount generated at the site more accurately.
The Institute of Livestock and Grassland science, NARO (NILGS) in collaboration with the Okayama Prefectural Agricultural, Forestry & Fisheries Research Center, Chiba Prefectural Livestock Research Center, Saga Livestock Research Laboratory, and Mitsubishi UFJ Research and Consulting, recalculated the emission factor of greenhouse gas (nitrous oxide and methane) generated by the sewage treatment of pigs and cattle that accounts for most of greenhouse gas emissions generated by waste in swine, dairy and meat cattle production, based on actual field measurement data.
As a result, it was found that the emission factor of nitrous oxide used at present is over-estimated. Using the latest emission factor, the estimated value of greenhouse gas emissions (total amount of nitrous oxide and methane) associated with swine and cattle sewage treatment is found to be reduced by 600kt CO2 eq. (decreased by 41%, calculated value in terms of carbon dioxide equivalent) annually compared with the estimated value using the current emission factor.
This calculated emission factor of nitrous oxide and methane will be adopted in National Greenhouse Gas Inventory Report of JAPAN and will be used in the future assessment of environmental impact caused by swine farming, dairy cattle and meat cattle production.
In addition, this accurate current emission factor will help to identify high priority emissions sources to be reduced, which will be useful for developing livestock production system with less environmental impact.
Takashi Osada, Makoto Shiraishi, Teruaki Hasegawa, Hirofumi Kawahara (2017) Front. Environ. Sci.
Eng. 11(3): 10. https://doi.org/10.1007/s11783-017-0933-7
Makoto Shiraishi, Takashi Osada, Takeshi Mizuki, Kenji Takatori (2017)Volume 88 Issue 4 Pages 479-490 https://doi.org/10.2508/chikusan.88.479