Carbon footprint
analysis is a method to quantify the life cycle Greenhouse Gases (GHGs)
emissions and identify the measure to reduce climate change impacts. The Intergovernmental Panel on Climate Change (IPCC) has identified
that the global warming and climate change which is one of the most important
issues in the domain of environment are caused by the excessive emission of
Greenhouse Gases (GHG) mainly constituting Carbon dioxide (CO2),
Methane (CH4) and Nitrous oxide (N2O). The municipal
wastewater treatment plant receives wastewater for treatment and finally
discharges the treated effluent. The emissions of GHG during the treatment of
wastewater as well as during the treatment process of sludge and also for
energy generation are known to be on-site GHG emissions. Off-site GHG emissions
are generated due to transportation and disposal of sludge, off-site energy and
chemical production.
In Puducherry, the municipal wastewater is being treated using
oxidation ponds, Upflow Anaerobic Sludge Blanket (UASB) and Sequencing Batch
Reactor (SBR). Wastewater treatment using Sequencing Batch Reactor (SBR)
technology is one of the state-of-the-art wastewater management systems. In
this technology equalization, biological treatment and secondary clarification
are performed in a single reactor in a time control sequence.
In this paper, the emissions of GHG from the
UASB, oxidation ponds and SBR in Puducherry were estimated. The emissions of CO2,
CH4 and N2O from all these treatment plants were also
estimated based on the guidelines of IPCC and RTI-USEPA and the total
equivalent CO2 was computed and analyzed. The impact of biomass
yield coefficient on the emissions of GHG was also examined and their
variations were also studied. The total emissions of equivalent CO2
from the SBR of 17 Mld capacity were less than 20% of the total CO2
emissions of CO2 from the UASB and oxidation ponds of 17.5 Mld
capacity. Further study revealed that by modifying the treatment process of the
sludge from the SBR, by altering the waste sludge flow rate and the MLSS, the
total emissions of equivalent CO2, could be reduced and it is
possible to achieve a reduction of about 40% of total equivalent CO2
emissions. The study also established that the emissions of CO2 from
the SBR are the least and that the SBR performs well and more efficient in
terms of reduction of GHG emissions when compared to that of the UASB and
oxidation ponds.
Article
by G. Vijayan, et al, from Puducherry, India.
Full
access: http://mrw.so/1gm7JV
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